Cough Variant Asthma

Complex MONDO:0001491 Respiratory Disease Asthma

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0
Mappings
0
Definitions
0
Inheritance
4
Pathophysiology
0
Histopathology
4
Phenotypes
0
Pathograph
0
Genes
3
Treatments
2
Subtypes
0
Differentials
0
Datasets
0
Trials
0
Models
1
Deep Research
🏷

Classifications

Harrison's Chapter
respiratory system disorder obstructive lung disease allergic disease
◆

Subtypes

2
Atopic Cough Variant Asthma
CVA associated with allergic sensitization and elevated IgE levels, triggered by aeroallergens. Similar proportion of atopy is seen in CVA as in classic asthma.
Show evidence (1 reference)
PMID:35127763 SUPPORT
"Despite lower total serum IgE levels in CVA, there was similar proportion of atopy in both groups."
Confirms atopic sensitization is common in CVA, supporting the existence of an atopic subtype.
Non-Atopic Cough Variant Asthma
CVA occurring without allergic sensitization, often triggered by respiratory infections, cold air, or irritants.
⚙

Pathophysiology

4
Eosinophilic Airway Inflammation
Eosinophilic infiltration of the bronchial mucosa with release of cytotoxic mediators causing epithelial damage and airway hyperresponsiveness. CVA shares type 2 inflammatory biology with classic asthma but typically shows lower eosinophilic biomarker levels despite comparable or greater cough burden, suggesting cough generation is not a simple linear function of eosinophil load.
eosinophil link T-helper 2 cell link mast cell link
inflammatory response link eosinophil migration link
bronchus link
Show evidence (4 references)
PMID:35127763 SUPPORT Human Clinical
"Cough variant asthma is distinctive from classic asthma in regard to clinical features, lung function, and airway inflammation."
Large multicenter APAC cohort demonstrates that CVA has measurable but lower type 2 inflammatory markers compared to classic asthma.
PMID:35127763 SUPPORT Human Clinical
"No correlation was found between cough assessment outcomes and sputum eosinophil count, blood eosinophil count, FENO, spirometry variables, or PD20-FEV1."
Demonstrates that cough severity in CVA is dissociated from eosinophilic inflammation intensity, suggesting additional cough-driving mechanisms beyond eosinophilia.
PMID:38566832 SUPPORT Human Clinical
"In the three groups of CVA patients, after receiving budesonide inhalation combined with conventional symptomatic treatment, the expression levels of serum IL-5, IL-6, IL-8, TNF-α, TGF-β1, and IgE and number of eosinophils significantly decreased (P <0.05)."
Confirms the presence of eosinophilic and cytokine-mediated inflammation in CVA that responds to inhaled corticosteroid treatment.
+ 1 more reference
Airway Hyperresponsiveness
Enhanced bronchoconstrictor response to nonspecific stimuli such as methacholine, representing the hallmark physiologic abnormality that distinguishes CVA from non-asthmatic eosinophilic bronchitis. CVA typically shows milder AHR than classic asthma but it remains a defining diagnostic criterion.
bronchial smooth muscle cell link bronchial epithelial cell link
smooth muscle contraction link
bronchus link
Show evidence (2 references)
PMID:35127763 SUPPORT Human Clinical
"CVA subjects showed a higher proportion of female (67.1 vs. 55.3%, P = 0.0084), abnormal laryngopharyngeal sensations (71 vs. 51%, p < 0.0001) than CA, but presented with near normal spirometry and higher methacholine PD20-FEV1 values"
Demonstrates AHR in CVA (positive methacholine challenge) but at milder levels than classic asthma, with higher PD20-FEV1 values.
PMID:34164212 SUPPORT Human Clinical
"The distinctive characteristic of these conditions is the presence of airway hyperresponsiveness in CVA but not in NAEB."
Establishes AHR as the key distinguishing feature between CVA and non-asthmatic eosinophilic bronchitis.
Cough Reflex Hypersensitivity
Heightened sensitivity of airway cough receptors including vagal C-fibers and rapidly adapting receptors, leading to exaggerated cough responses to normally innocuous stimuli. Cough hypersensitivity symptom profiles are similar between asthmatic cough and refractory chronic cough, suggesting a shared neuronal mechanism across chronic cough phenotypes.
bronchial epithelial cell link
bronchus link
Show evidence (3 references)
PMID:39534772 SUPPORT Human Clinical
"The symptoms of cough hypersensitivity may not distinguish between asthmatic cough and RCC. This suggests that chronic cough is the primary diagnosis in both phenotypes. It indicates a shared mechanism in their cough pathogenesis, despite having potentially different treatable traits."
Demonstrates that cough hypersensitivity is a shared mechanism between CVA and refractory chronic cough, supporting cough reflex hypersensitivity as a core feature of CVA.
PMID:37969279 SUPPORT Human Clinical
"Cough reflex hypersensitivity (CRH) has also been reported in asthma, COPD, bronchiectasis, ILD and sarcoidosis."
State-of-the-art review confirms cough reflex hypersensitivity in asthma, supporting it as a mechanism in CVA.
PMID:35127763 SUPPORT Human Clinical
"abnormal laryngopharyngeal sensations (71 vs. 51%, p < 0.0001) than CA"
Higher prevalence of abnormal laryngopharyngeal sensations in CVA compared to classic asthma supports heightened cough reflex sensitivity as a prominent feature.
Small Airway Dysfunction
Small airway dysfunction is highly prevalent in CVA and frequently persists after short-term antiasthmatic treatment despite improvement in symptoms and inflammatory markers. This may contribute to disease chronicity and risk of progression to classic asthma.
bronchiole link
Show evidence (3 references)
PMID:35095550 SUPPORT Human Clinical
"SAD occurred in 73 (60.8%) patients with CVA before treatment."
Demonstrates high prevalence of small airway dysfunction in corticosteroid-naive CVA patients.
PMID:35095550 SUPPORT Human Clinical
"Among 105 patients who completed 2 months of antiasthmatic treatment and repeatedly experienced spirometry measurement, 57 (54.3%) patients still had SAD, despite a significant improvement in cough VAS, sputum eosinophils, FeNO, FEF50% pred, and PEF% pred (all p < 0.01)."
SAD persists in over half of CVA patients after 2 months of treatment despite improvement in other parameters, suggesting a treatment-resistant component.
PMID:35095550 SUPPORT Human Clinical
"Small airway dysfunction occurred in over half of patients with CVA and persisted after short-term antiasthmatic treatment, which showed distinctive clinical and pathophysiological features."
Confirms SAD as a distinct pathophysiological feature of CVA.
●

Phenotypes

4
Respiratory 3
Chronic Dry Cough OBLIGATE Chronic cough (HP:0034315)
Show evidence (2 references)
PMID:34164212 SUPPORT Human Clinical
"Cough variant asthma (CVA) is a phenotype of asthma which lacks wheezing or dyspnea, and consistently one of the most common causes of chronic cough worldwide."
Establishes chronic cough as the defining and predominant symptom of CVA.
PMID:35127763 SUPPORT Human Clinical
"CVA reported more severe cough on Visual Analog Scale, Cough Evaluation Test, and Leicester Cough Questionnaire"
Demonstrates that cough severity is paradoxically higher in CVA than classic asthma despite lower inflammatory biomarkers.
Nonproductive Cough VERY_FREQUENT Nonproductive cough (HP:0031246)
Show evidence (1 reference)
PMID:34164212 SUPPORT Human Clinical
"CVA and non-asthmatic eosinophilic bronchitis (NAEB) shares common feature such as chronic dry cough, eosinophilic inflammation, and development of chronic airflow obstruction (CAO) and asthma in a subset of patients."
Confirms chronic dry cough as a shared feature of CVA.
Wheezing OCCASIONAL Wheezing (HP:0030828)
Show evidence (1 reference)
PMID:34164212 SUPPORT Human Clinical
"Cough variant asthma (CVA) is a phenotype of asthma which lacks wheezing or dyspnea"
Confirms that CVA characteristically lacks wheezing, making it an occasional rather than defining feature.
Other 1
Abnormal Laryngopharyngeal Sensations VERY_FREQUENT
Show evidence (1 reference)
PMID:35127763 SUPPORT Human Clinical
"abnormal laryngopharyngeal sensations (71 vs. 51%, p < 0.0001) than CA"
71% of CVA patients report abnormal laryngopharyngeal sensations, significantly higher than in classic asthma.
💊

Treatments

3
Inhaled Corticosteroids
Action: inhaled corticosteroid agent therapy MAXO:0000314
First-line treatment that reduces eosinophilic airway inflammation, inflammatory cytokines, and cough symptom scores. Budesonide inhalation achieves complete remission in approximately 56% and partial remission in 36% of CVA patients at 8 weeks.
Show evidence (2 references)
PMID:38566832 SUPPORT Human Clinical
"Budesonide inhalation combined with conventional symptomatic treatment can significantly reduce the levels of serum inflammatory factors in patients with CVA to reduce inflammation and the allergic response, thereby reducing the cough symptom score, improving pulmonary function, and improving..."
Demonstrates efficacy of inhaled budesonide in reducing inflammation and improving symptoms in CVA, with biomarker-guided early response prediction.
PMID:34164212 SUPPORT Human Clinical
"Inhaled corticosteroids (ICSs) are the first-line treatment, and leukotriene receptor antagonists are also effective, in patients with both CVA and NAEB."
Confirms ICS as first-line treatment for CVA.
Bronchodilator Therapy
Action: bronchodilator therapy MAXO:0000316
Short-acting beta-2 agonists provide symptomatic relief, and cough responsiveness to bronchodilators is a distinguishing feature of CVA versus non-asthmatic eosinophilic bronchitis.
Show evidence (1 reference)
PMID:34164212 SUPPORT Human Clinical
"Coughing is responsive to bronchodilators such as beta-agonists in CVA, but such feature has not been clarified in NAEB."
Confirms bronchodilator responsiveness of cough as a diagnostic feature of CVA.
Leukotriene Receptor Antagonists
Action: antileukotriene agent therapy MAXO:0000315
Montelukast and similar agents are effective adjunctive therapy for CVA, particularly in patients with concurrent allergic rhinitis.
Show evidence (1 reference)
PMID:34164212 SUPPORT Human Clinical
"Inhaled corticosteroids (ICSs) are the first-line treatment, and leukotriene receptor antagonists are also effective, in patients with both CVA and NAEB."
Confirms leukotriene receptor antagonists as an effective treatment for CVA.
🌍

Environmental Factors

3
Allergen Exposure
Exposure to common aeroallergens such as house dust mite, pollens, moulds, and animal dander can trigger or exacerbate CVA in atopic individuals. Sensitization to multiple allergens is associated with progression to classic asthma with wheezing.
Show evidence (2 references)
PMID:17941915 SUPPORT Human Clinical
"To prevent the progression of cough variant asthma to classic asthma, avoidance of relevant allergens may be essential."
Direct clinical study of 74 CVA patients showing aeroallergen sensitization (HDM, pollens, moulds, dander) in CVA and recommending allergen avoidance.
PMID:17941915 SUPPORT Human Clinical
"Wheezing developed in six (15%) patients with cough variant asthma, who were sensitized to larger numbers of allergens (P=0.02) and had higher rates of sensitization to HDM (P=0.01) and dog dander (P=0.02) than the 34 patients in whom wheezing did not develop."
Multi-allergen sensitization in CVA patients is directly linked to progression risk, establishing allergens as clinically relevant triggers.
Cold Air Exposure
Inhalation of cold dry air is a well-recognized trigger of cough in CVA patients.
Upper Respiratory Infections
Viral upper respiratory tract infections frequently precede the onset of CVA or trigger exacerbations.
{ }

Source YAML

click to show 
name: Cough Variant Asthma
creation_date: "2026-03-04T12:00:00Z"
updated_date: "2026-03-04T12:00:00Z"
category: Complex
disease_term:
  preferred_term: cough variant asthma
  term:
    id: MONDO:0001491
    label: cough variant asthma
parents:
  - Respiratory Disease
  - Asthma
has_subtypes:
  - name: Atopic Cough Variant Asthma
    description: CVA associated with allergic sensitization and elevated IgE levels, triggered by aeroallergens. Similar proportion of atopy is seen in CVA as in classic asthma.
    evidence:
      - reference: PMID:35127763
        reference_title: "Clinical and Inflammatory Characteristics of the Chinese APAC Cough Variant Asthma Cohort."
        supports: SUPPORT
        snippet: Despite lower total serum IgE levels in CVA, there was similar proportion of atopy in both groups.
        explanation: Confirms atopic sensitization is common in CVA, supporting the existence of an atopic subtype.
  - name: Non-Atopic Cough Variant Asthma
    description: CVA occurring without allergic sensitization, often triggered by respiratory infections, cold air, or irritants.
pathophysiology:
  - name: Eosinophilic Airway Inflammation
    description: >
      Eosinophilic infiltration of the bronchial mucosa with release of cytotoxic mediators causing
      epithelial damage and airway hyperresponsiveness. CVA shares type 2 inflammatory biology with
      classic asthma but typically shows lower eosinophilic biomarker levels despite comparable or
      greater cough burden, suggesting cough generation is not a simple linear function of eosinophil
      load.
    cell_types:
      - preferred_term: eosinophil
        term:
          id: CL:0000771
          label: eosinophil
      - preferred_term: T-helper 2 cell
        term:
          id: CL:0000546
          label: T-helper 2 cell
      - preferred_term: mast cell
        term:
          id: CL:0000097
          label: mast cell
    biological_processes:
      - preferred_term: inflammatory response
        term:
          id: GO:0006954
          label: inflammatory response
      - preferred_term: eosinophil migration
        term:
          id: GO:0072677
          label: eosinophil migration
    locations:
      - preferred_term: bronchus
        term:
          id: UBERON:0002185
          label: bronchus
    evidence:
      - reference: PMID:35127763
        reference_title: "Clinical and Inflammatory Characteristics of the Chinese APAC Cough Variant Asthma Cohort."
        supports: SUPPORT
        evidence_source: HUMAN_CLINICAL
        snippet: "Cough variant asthma is distinctive from classic asthma in regard to clinical features, lung function, and airway inflammation."
        explanation: Large multicenter APAC cohort demonstrates that CVA has measurable but lower type 2 inflammatory markers compared to classic asthma.
      - reference: PMID:35127763
        reference_title: "Clinical and Inflammatory Characteristics of the Chinese APAC Cough Variant Asthma Cohort."
        supports: SUPPORT
        evidence_source: HUMAN_CLINICAL
        snippet: "No correlation was found between cough assessment outcomes and sputum eosinophil count, blood eosinophil count, FENO, spirometry variables, or PD20-FEV1."
        explanation: Demonstrates that cough severity in CVA is dissociated from eosinophilic inflammation intensity, suggesting additional cough-driving mechanisms beyond eosinophilia.
      - reference: PMID:38566832
        reference_title: "The Effects of Budesonide Inhalation Treatment on the Expression Levels of Serum IL-6, TGF-β1, and IgE and Pulmonary Function in Patients with Cough Variant Asthma and an Evaluation of Treatment Efficacy."
        supports: SUPPORT
        evidence_source: HUMAN_CLINICAL
        snippet: "In the three groups of CVA patients, after receiving budesonide inhalation combined with conventional symptomatic treatment, the expression levels of serum IL-5, IL-6, IL-8, TNF-α, TGF-β1, and IgE and number of eosinophils significantly decreased (P <0.05)."
        explanation: Confirms the presence of eosinophilic and cytokine-mediated inflammation in CVA that responds to inhaled corticosteroid treatment.
      - reference: PMID:34164212
        reference_title: "Narrative Review: how long should patients with cough variant asthma or non-asthmatic eosinophilic bronchitis be treated?"
        supports: SUPPORT
        evidence_source: HUMAN_CLINICAL
        snippet: "approximately 30% to 50% of people with chronic cough have eosinophilic airway inflammation, the presence of which can be confirmed by sputum eosinophilia or elevated exhaled nitric-oxide levels."
        explanation: Establishes eosinophilic airway inflammation as a common feature of chronic cough conditions including CVA.
  - name: Airway Hyperresponsiveness
    description: >
      Enhanced bronchoconstrictor response to nonspecific stimuli such as methacholine,
      representing the hallmark physiologic abnormality that distinguishes CVA from
      non-asthmatic eosinophilic bronchitis. CVA typically shows milder AHR than classic
      asthma but it remains a defining diagnostic criterion.
    cell_types:
      - preferred_term: bronchial smooth muscle cell
        term:
          id: CL:0002598
          label: bronchial smooth muscle cell
      - preferred_term: bronchial epithelial cell
        term:
          id: CL:0002328
          label: bronchial epithelial cell
    biological_processes:
      - preferred_term: smooth muscle contraction
        term:
          id: GO:0006939
          label: smooth muscle contraction
    locations:
      - preferred_term: bronchus
        term:
          id: UBERON:0002185
          label: bronchus
    evidence:
      - reference: PMID:35127763
        reference_title: "Clinical and Inflammatory Characteristics of the Chinese APAC Cough Variant Asthma Cohort."
        supports: SUPPORT
        evidence_source: HUMAN_CLINICAL
        snippet: "CVA subjects showed a higher proportion of female (67.1 vs. 55.3%, P = 0.0084), abnormal laryngopharyngeal sensations (71 vs. 51%, p < 0.0001) than CA, but presented with near normal spirometry and higher methacholine PD20-FEV1 values"
        explanation: Demonstrates AHR in CVA (positive methacholine challenge) but at milder levels than classic asthma, with higher PD20-FEV1 values.
      - reference: PMID:34164212
        reference_title: "Narrative Review: how long should patients with cough variant asthma or non-asthmatic eosinophilic bronchitis be treated?"
        supports: SUPPORT
        evidence_source: HUMAN_CLINICAL
        snippet: "The distinctive characteristic of these conditions is the presence of airway hyperresponsiveness in CVA but not in NAEB."
        explanation: Establishes AHR as the key distinguishing feature between CVA and non-asthmatic eosinophilic bronchitis.
  - name: Cough Reflex Hypersensitivity
    description: >
      Heightened sensitivity of airway cough receptors including vagal C-fibers and rapidly
      adapting receptors, leading to exaggerated cough responses to normally innocuous stimuli.
      Cough hypersensitivity symptom profiles are similar between asthmatic cough and refractory
      chronic cough, suggesting a shared neuronal mechanism across chronic cough phenotypes.
    cell_types:
      - preferred_term: bronchial epithelial cell
        term:
          id: CL:0002328
          label: bronchial epithelial cell
    locations:
      - preferred_term: bronchus
        term:
          id: UBERON:0002185
          label: bronchus
    evidence:
      - reference: PMID:39534772
        reference_title: "Could cough hypersensitivity symptom profile differentiate phenotypes of chronic cough?"
        supports: SUPPORT
        evidence_source: HUMAN_CLINICAL
        snippet: "The symptoms of cough hypersensitivity may not distinguish between asthmatic cough and RCC. This suggests that chronic cough is the primary diagnosis in both phenotypes. It indicates a shared mechanism in their cough pathogenesis, despite having potentially different treatable traits."
        explanation: Demonstrates that cough hypersensitivity is a shared mechanism between CVA and refractory chronic cough, supporting cough reflex hypersensitivity as a core feature of CVA.
      - reference: PMID:37969279
        reference_title: "Cough in chronic lung disease: a state of the art review."
        supports: SUPPORT
        evidence_source: HUMAN_CLINICAL
        snippet: "Cough reflex hypersensitivity (CRH) has also been reported in asthma, COPD, bronchiectasis, ILD and sarcoidosis."
        explanation: State-of-the-art review confirms cough reflex hypersensitivity in asthma, supporting it as a mechanism in CVA.
      - reference: PMID:35127763
        reference_title: "Clinical and Inflammatory Characteristics of the Chinese APAC Cough Variant Asthma Cohort."
        supports: SUPPORT
        evidence_source: HUMAN_CLINICAL
        snippet: "abnormal laryngopharyngeal sensations (71 vs. 51%, p < 0.0001) than CA"
        explanation: Higher prevalence of abnormal laryngopharyngeal sensations in CVA compared to classic asthma supports heightened cough reflex sensitivity as a prominent feature.
  - name: Small Airway Dysfunction
    description: >
      Small airway dysfunction is highly prevalent in CVA and frequently persists after
      short-term antiasthmatic treatment despite improvement in symptoms and inflammatory
      markers. This may contribute to disease chronicity and risk of progression to classic
      asthma.
    locations:
      - preferred_term: bronchiole
        term:
          id: UBERON:0002186
          label: bronchiole
    evidence:
      - reference: PMID:35095550
        reference_title: "Small Airway Dysfunction in Cough Variant Asthma: Prevalence, Clinical, and Pathophysiological Features."
        supports: SUPPORT
        evidence_source: HUMAN_CLINICAL
        snippet: "SAD occurred in 73 (60.8%) patients with CVA before treatment."
        explanation: Demonstrates high prevalence of small airway dysfunction in corticosteroid-naive CVA patients.
      - reference: PMID:35095550
        reference_title: "Small Airway Dysfunction in Cough Variant Asthma: Prevalence, Clinical, and Pathophysiological Features."
        supports: SUPPORT
        evidence_source: HUMAN_CLINICAL
        snippet: "Among 105 patients who completed 2 months of antiasthmatic treatment and repeatedly experienced spirometry measurement, 57 (54.3%) patients still had SAD, despite a significant improvement in cough VAS, sputum eosinophils, FeNO, FEF50% pred, and PEF% pred (all p < 0.01)."
        explanation: SAD persists in over half of CVA patients after 2 months of treatment despite improvement in other parameters, suggesting a treatment-resistant component.
      - reference: PMID:35095550
        reference_title: "Small Airway Dysfunction in Cough Variant Asthma: Prevalence, Clinical, and Pathophysiological Features."
        supports: SUPPORT
        evidence_source: HUMAN_CLINICAL
        snippet: "Small airway dysfunction occurred in over half of patients with CVA and persisted after short-term antiasthmatic treatment, which showed distinctive clinical and pathophysiological features."
        explanation: Confirms SAD as a distinct pathophysiological feature of CVA.
phenotypes:
  - category: RESPIRATORY
    name: Chronic Dry Cough
    frequency: OBLIGATE
    description: >
      Persistent nonproductive cough lasting more than 8 weeks, the defining symptom of CVA.
      Cough burden is typically more severe than in classic asthma despite milder inflammatory
      biomarker levels.
    phenotype_term:
      preferred_term: Chronic cough
      term:
        id: HP:0034315
        label: Chronic cough
    evidence:
      - reference: PMID:34164212
        reference_title: "Narrative Review: how long should patients with cough variant asthma or non-asthmatic eosinophilic bronchitis be treated?"
        supports: SUPPORT
        evidence_source: HUMAN_CLINICAL
        snippet: "Cough variant asthma (CVA) is a phenotype of asthma which lacks wheezing or dyspnea, and consistently one of the most common causes of chronic cough worldwide."
        explanation: Establishes chronic cough as the defining and predominant symptom of CVA.
      - reference: PMID:35127763
        reference_title: "Clinical and Inflammatory Characteristics of the Chinese APAC Cough Variant Asthma Cohort."
        supports: SUPPORT
        evidence_source: HUMAN_CLINICAL
        snippet: "CVA reported more severe cough on Visual Analog Scale, Cough Evaluation Test, and Leicester Cough Questionnaire"
        explanation: Demonstrates that cough severity is paradoxically higher in CVA than classic asthma despite lower inflammatory biomarkers.
  - category: RESPIRATORY
    name: Nonproductive Cough
    frequency: VERY_FREQUENT
    description: Cough is characteristically dry and nonproductive in CVA.
    phenotype_term:
      preferred_term: Nonproductive cough
      term:
        id: HP:0031246
        label: Nonproductive cough
    evidence:
      - reference: PMID:34164212
        reference_title: "Narrative Review: how long should patients with cough variant asthma or non-asthmatic eosinophilic bronchitis be treated?"
        supports: SUPPORT
        evidence_source: HUMAN_CLINICAL
        snippet: "CVA and non-asthmatic eosinophilic bronchitis (NAEB) shares common feature such as chronic dry cough, eosinophilic inflammation, and development of chronic airflow obstruction (CAO) and asthma in a subset of patients."
        explanation: Confirms chronic dry cough as a shared feature of CVA.
  - category: RESPIRATORY
    name: Abnormal Laryngopharyngeal Sensations
    frequency: VERY_FREQUENT
    description: >
      Abnormal throat sensations such as tickle, itch, or globus sensation are more common
      in CVA than in classic asthma and may reflect cough reflex hypersensitivity.
    evidence:
      - reference: PMID:35127763
        reference_title: "Clinical and Inflammatory Characteristics of the Chinese APAC Cough Variant Asthma Cohort."
        supports: SUPPORT
        evidence_source: HUMAN_CLINICAL
        snippet: "abnormal laryngopharyngeal sensations (71 vs. 51%, p < 0.0001) than CA"
        explanation: 71% of CVA patients report abnormal laryngopharyngeal sensations, significantly higher than in classic asthma.
  - category: RESPIRATORY
    name: Wheezing
    frequency: OCCASIONAL
    description: >
      Mild or intermittent wheezing may occasionally occur, but absence of wheeze is
      characteristic of CVA and distinguishes it from classic asthma. A subset of patients
      may progress to develop wheezing over time.
    phenotype_term:
      preferred_term: Wheezing
      term:
        id: HP:0030828
        label: Wheezing
    evidence:
      - reference: PMID:34164212
        reference_title: "Narrative Review: how long should patients with cough variant asthma or non-asthmatic eosinophilic bronchitis be treated?"
        supports: SUPPORT
        evidence_source: HUMAN_CLINICAL
        snippet: "Cough variant asthma (CVA) is a phenotype of asthma which lacks wheezing or dyspnea"
        explanation: Confirms that CVA characteristically lacks wheezing, making it an occasional rather than defining feature.
environmental:
  - name: Allergen Exposure
    description: Exposure to common aeroallergens such as house dust mite, pollens, moulds, and animal dander can trigger or exacerbate CVA in atopic individuals. Sensitization to multiple allergens is associated with progression to classic asthma with wheezing.
    evidence:
      - reference: PMID:17941915
        reference_title: "Atopic features of cough variant asthma and classic asthma with wheezing."
        supports: SUPPORT
        evidence_source: HUMAN_CLINICAL
        snippet: "To prevent the progression of cough variant asthma to classic asthma, avoidance of relevant allergens may be essential."
        explanation: Direct clinical study of 74 CVA patients showing aeroallergen sensitization (HDM, pollens, moulds, dander) in CVA and recommending allergen avoidance.
      - reference: PMID:17941915
        reference_title: "Atopic features of cough variant asthma and classic asthma with wheezing."
        supports: SUPPORT
        evidence_source: HUMAN_CLINICAL
        snippet: "Wheezing developed in six (15%) patients with cough variant asthma, who were sensitized to larger numbers of allergens (P=0.02) and had higher rates of sensitization to HDM (P=0.01) and dog dander (P=0.02) than the 34 patients in whom wheezing did not develop."
        explanation: Multi-allergen sensitization in CVA patients is directly linked to progression risk, establishing allergens as clinically relevant triggers.
  - name: Cold Air Exposure
    description: Inhalation of cold dry air is a well-recognized trigger of cough in CVA patients.
  - name: Upper Respiratory Infections
    description: Viral upper respiratory tract infections frequently precede the onset of CVA or trigger exacerbations.
treatments:
  - name: Inhaled Corticosteroids
    description: >
      First-line treatment that reduces eosinophilic airway inflammation, inflammatory
      cytokines, and cough symptom scores. Budesonide inhalation achieves complete
      remission in approximately 56% and partial remission in 36% of CVA patients at
      8 weeks.
    treatment_term:
      preferred_term: inhaled corticosteroid agent therapy
      term:
        id: MAXO:0000314
        label: inhaled corticosteroid agent therapy
    evidence:
      - reference: PMID:38566832
        reference_title: "The Effects of Budesonide Inhalation Treatment on the Expression Levels of Serum IL-6, TGF-β1, and IgE and Pulmonary Function in Patients with Cough Variant Asthma and an Evaluation of Treatment Efficacy."
        supports: SUPPORT
        evidence_source: HUMAN_CLINICAL
        snippet: "Budesonide inhalation combined with conventional symptomatic treatment can significantly reduce the levels of serum inflammatory factors in patients with CVA to reduce inflammation and the allergic response, thereby reducing the cough symptom score, improving pulmonary function, and improving therapeutic efficacy."
        explanation: Demonstrates efficacy of inhaled budesonide in reducing inflammation and improving symptoms in CVA, with biomarker-guided early response prediction.
      - reference: PMID:34164212
        reference_title: "Narrative Review: how long should patients with cough variant asthma or non-asthmatic eosinophilic bronchitis be treated?"
        supports: SUPPORT
        evidence_source: HUMAN_CLINICAL
        snippet: "Inhaled corticosteroids (ICSs) are the first-line treatment, and leukotriene receptor antagonists are also effective, in patients with both CVA and NAEB."
        explanation: Confirms ICS as first-line treatment for CVA.
  - name: Bronchodilator Therapy
    description: >
      Short-acting beta-2 agonists provide symptomatic relief, and cough responsiveness
      to bronchodilators is a distinguishing feature of CVA versus non-asthmatic
      eosinophilic bronchitis.
    treatment_term:
      preferred_term: bronchodilator therapy
      term:
        id: MAXO:0000316
        label: bronchodilator therapy
    evidence:
      - reference: PMID:34164212
        reference_title: "Narrative Review: how long should patients with cough variant asthma or non-asthmatic eosinophilic bronchitis be treated?"
        supports: SUPPORT
        evidence_source: HUMAN_CLINICAL
        snippet: "Coughing is responsive to bronchodilators such as beta-agonists in CVA, but such feature has not been clarified in NAEB."
        explanation: Confirms bronchodilator responsiveness of cough as a diagnostic feature of CVA.
  - name: Leukotriene Receptor Antagonists
    description: >
      Montelukast and similar agents are effective adjunctive therapy for CVA, particularly
      in patients with concurrent allergic rhinitis.
    treatment_term:
      preferred_term: antileukotriene agent therapy
      term:
        id: MAXO:0000315
        label: antileukotriene agent therapy
    evidence:
      - reference: PMID:34164212
        reference_title: "Narrative Review: how long should patients with cough variant asthma or non-asthmatic eosinophilic bronchitis be treated?"
        supports: SUPPORT
        evidence_source: HUMAN_CLINICAL
        snippet: "Inhaled corticosteroids (ICSs) are the first-line treatment, and leukotriene receptor antagonists are also effective, in patients with both CVA and NAEB."
        explanation: Confirms leukotriene receptor antagonists as an effective treatment for CVA.
prevalence:
  - population: Global
    notes: >
      CVA is consistently one of the most common causes of chronic cough worldwide. The
      prevalence of chronic cough in asthma ranges from 8-58% across cohorts.
    evidence:
      - reference: PMID:37969279
        reference_title: "Cough in chronic lung disease: a state of the art review."
        supports: SUPPORT
        evidence_source: HUMAN_CLINICAL
        snippet: "The prevalence of CC in respiratory diseases is poorly described, but estimates have been reported: asthma (8-58%)"
        explanation: Provides prevalence estimates for chronic cough in asthma populations, contextualizing CVA within the broader asthma spectrum.
      - reference: PMID:34164212
        reference_title: "Narrative Review: how long should patients with cough variant asthma or non-asthmatic eosinophilic bronchitis be treated?"
        supports: SUPPORT
        evidence_source: HUMAN_CLINICAL
        snippet: "Cough variant asthma (CVA) is a phenotype of asthma which lacks wheezing or dyspnea, and consistently one of the most common causes of chronic cough worldwide."
        explanation: Establishes CVA as a globally common cause of chronic cough.
diagnosis:
  - name: Methacholine Bronchial Provocation Test
    description: >
      Demonstration of airway hyperresponsiveness via positive methacholine challenge
      (PC20 <16 mg/mL) is a key diagnostic criterion for CVA, distinguishing it from
      non-asthmatic eosinophilic bronchitis.
    evidence:
      - reference: PMID:34164212
        reference_title: "Narrative Review: how long should patients with cough variant asthma or non-asthmatic eosinophilic bronchitis be treated?"
        supports: SUPPORT
        evidence_source: HUMAN_CLINICAL
        snippet: "The distinctive characteristic of these conditions is the presence of airway hyperresponsiveness in CVA but not in NAEB."
        explanation: Explicitly identifies airway hyperresponsiveness (demonstrated by methacholine challenge) as the defining diagnostic feature that distinguishes CVA from non-asthmatic eosinophilic bronchitis.
  - name: Therapeutic Trial Response
    description: >
      Resolution of cough with bronchodilator or inhaled corticosteroid therapy confirms
      the diagnosis of CVA. Response to anti-asthma treatment at 6 months validates
      the phenotype classification.
    evidence:
      - reference: PMID:34164212
        reference_title: "Narrative Review: how long should patients with cough variant asthma or non-asthmatic eosinophilic bronchitis be treated?"
        supports: SUPPORT
        evidence_source: HUMAN_CLINICAL
        snippet: "Coughing is responsive to bronchodilators such as beta-agonists in CVA"
        explanation: Bronchodilator responsiveness of cough is a diagnostic feature distinguishing CVA from other chronic cough causes.
classifications:
  harrisons_chapter:
    - classification_value: respiratory system disorder
    - classification_value: obstructive lung disease
    - classification_value: allergic disease
notes: >
  CVA research is still in development with no unified definition of pathogenesis, diagnostic
  criteria or treatment strategies. Approximately 30% of untreated CVA patients may progress
  to classic asthma with wheezing over 3-5 years, with early inhaled corticosteroid therapy
  potentially reducing this risk. Long-term treatment may be necessary to prevent airway
  remodeling from mechanical stress of chronic coughing.
📚

References & Deep Research

Deep Research

1
Falcon ▸
Disease Pathophysiology Research Template
Edison Scientific Literature 24 citations 2026-03-04T10:30:39.854521

Question: You are an expert researcher providing comprehensive, well-cited information.

Provide detailed information focusing on: 1. Key concepts and definitions with current understanding 2. Recent developments and latest research (prioritize 2023-2024 sources) 3. Current applications and real-world implementations 4. Expert opinions and analysis from authoritative sources 5. Relevant statistics and data from recent studies

Format as a comprehensive research report with proper citations. Include URLs and publication dates where available. Always prioritize recent, authoritative sources and provide specific citations for all major claims.

Disease Pathophysiology Research Template

Target Disease

  • Disease Name: Cough Variant Asthma
  • MONDO ID: (if available)
  • Category: Complex

Research Objectives

Please provide a comprehensive research report on the pathophysiology of Cough Variant Asthma. Focus on the molecular and cellular mechanisms underlying disease progression.

Required Information

1. Core Pathophysiology

  • What are the primary pathophysiological mechanisms?
  • What molecular pathways are dysregulated?
  • What cellular processes are affected?

2. Key Molecular Players

  • Genes/Proteins: Which genes are causally involved or implicated?
  • Chemical Entities: What metabolites, drugs, or small molecules are relevant?
  • Cell Types: Which cell types are primarily affected?
  • Anatomical Locations: Which tissues/organs are involved?

3. Biological Processes (for GO annotation)

  • What biological processes (GO terms) are disrupted?
  • Consider: signaling pathways, metabolic processes, cellular responses, transport, etc.

4. Cellular Components

  • Where in the cell do key processes occur?
  • Consider: organelles, membrane compartments, extracellular space, etc.

5. Disease Progression

  • What is the sequence of events from initial trigger to clinical manifestation?
  • Are there distinct stages or phases?

6. Phenotypic Manifestations

  • What are the key clinical phenotypes?
  • How do they relate to the underlying mechanisms?

Citation Requirements

  • Cite primary literature (PMID preferred) for all mechanistic claims
  • Prioritize recent reviews and landmark papers
  • Include direct quotes where possible to support key statements

Output Format

Structure your response as a narrative that could be used to populate a disease knowledge base entry with: - Pathophysiology description - Gene/protein annotations with ontology terms (HGNC, GO) - Phenotype associations (HP terms) - Cell type involvement (CL terms) - Anatomical locations (UBERON terms) - Chemical entities (CHEBI terms) - Evidence items with PMIDs

Comprehensive Research Report: Pathophysiology of Cough Variant Asthma (CVA)

Target disease

  • Disease name: Cough Variant Asthma (CVA)
  • MONDO ID: Not identified from the retrieved sources in this run (not available in current context).
  • Category: Complex (chronic inflammatory airway disease phenotype)

1) Key concepts and definitions (current understanding)

Definition / clinical concept

Cough variant asthma is commonly conceptualized as an asthma phenotype in which chronic cough is the predominant (sometimes sole) symptom, in contrast to classic asthma where wheeze and dyspnea are typical. In contemporary chronic cough phenotyping work, “asthmatic cough” is often defined to include CVA and eosinophilic bronchitis, operationalized with objective evidence of asthma biology/physiology and confirmed treatment response. In a 2024 prospective registry study, asthmatic cough required objective evidence of bronchodilator reversibility, airway hyperresponsiveness, and/or type 2 inflammation, and then confirmation by response to anti-asthmatic treatment. (kim2024couldcoughhypersensitivity pages 2-3)

Operational diagnostic thresholds used (2024 registry): - Bronchodilator response (BDR+): ≥12% and ≥200 mL increase in FEV1 - Methacholine AHR: PC20 <16 mg/mL - Type 2 inflammation: FeNO ≥25 ppb and/or sputum eosinophils ≥3% and/or blood eosinophils ≥300/µL (kim2024couldcoughhypersensitivity pages 2-3)

CVA as an “atypical asthma” phenotype and potential “pre-asthmatic” state

A 2024 review focused on atypical asthma phenotypes frames CVA as part of “atypical asthma” and notes the hypothesis that small airway inflammation → small airway dysfunction may underlie atypical presentations, while also acknowledging that peripheral/small-airway inflammation is less characterized in CVA than in classic asthma. (han2024smallairwayinflammation pages 1-2)

2) Core pathophysiology (molecular and cellular mechanisms)

CVA pathophysiology is best understood as an overlap of (i) asthma biology (airway inflammation and AHR) and (ii) chronic cough biology (cough reflex hypersensitivity), with phenotype-specific differences in the intensity and distribution of inflammation and physiologic dysfunction.

2.1 Type 2 (T2) airway inflammation: present but often quantitatively lower than classic asthma

A large multicenter cohort comparing newly diagnosed adults with CVA (n=328) versus mild–moderate classic asthma (n=206) found that CVA had lower canonical T2 biomarkers despite more severe cough symptoms: - FeNO: 38.5 vs 53 (median; P=0.0019) - Blood eosinophils: 0.2 vs 0.3 (median; P=0.0014) - Sputum eosinophils: 2.3% vs 12.2% (median; P<0.0001) - AHR severity: milder in CVA (higher methacholine PD20-FEV1: 4.2 vs 0.8; P<0.0001) (lai2022clinicalandinflammatory pages 1-2)

A key clinical interpretation from this cohort is mechanistically important: cough burden did not correlate with eosinophilic markers, spirometry, or PD20 (“No correlation was found…”), suggesting that cough generation in CVA is not a simple linear function of eosinophil load or AHR severity. (lai2022clinicalandinflammatory pages 1-2)

2.2 Airway hyperresponsiveness (AHR) as a core physiologic trait

CVA is frequently identified by positive bronchial provocation, and AHR is a central concept in contemporary registry phenotyping (PC20 <16 mg/mL). (kim2024couldcoughhypersensitivity pages 2-3)

Bibliometric synthesis of the field (2024) emphasizes airway inflammation and AHR as leading research foci and notes literature linking AHR to later wheeze/classic asthma features. (zhu2024bibliometricanalysisof pages 16-18)

2.3 Cough reflex hypersensitivity (CRH): neuronal dysregulation as a “treatable trait”

Modern cough pathophysiology increasingly highlights cough reflex hypersensitivity. A 2023 state-of-the-art review reported that heightened cough reflex sensitivity occurs in asthma and can be quantified by capsaicin challenge; one cited comparison showed markedly lower capsaicin C5 thresholds in asthma versus controls (62.5 vs >500 μM; P<0.001). (hirons2023coughinchronic pages 2-4)

A 2024 ERJ Open Research registry analysis found that cough hypersensitivity symptom profiles (triggers and laryngeal sensations) were similar between asthmatic cough (CVA/EB) and refractory chronic cough, supporting shared neuronal mechanisms across chronic cough phenotypes even when treatable traits differ. (kim2024couldcoughhypersensitivity pages 2-3)

Putative molecular sensors: Although CVA-specific mechanistic human omics were not available in 2023–2024 full text in this run, cough neurobiology commonly implicates TRP channels (e.g., TRPV1/TRPA1) as cough sensory transducers; this is consistent with the mechanistic framing of cough reflex hypersensitivity in asthma broadly. (hirons2023coughinchronic pages 2-4)

2.4 Small airway dysfunction (SAD): high prevalence and persistence

Small airway involvement is increasingly emphasized in atypical asthma. In a CVA cohort (n=120 corticosteroid-naïve), SAD was common (60.8%) and persisted in 54.3% after 2 months of anti-asthma treatment despite improvement in symptoms and inflammatory measures. (yi2022smallairwaydysfunction pages 1-2)

This supports a model in which CVA symptoms may be driven by a combination of AHR and cough hypersensitivity with peripheral airway functional impairment that may be relatively treatment-resistant over short horizons. (han2024smallairwayinflammation pages 1-2, yi2022smallairwaydysfunction pages 1-2)

3) Key molecular players, cell types, and anatomical locations

3.1 Genes/proteins (HGNC)

The most consistently implicated (and clinically actioned) molecular axes in the retrieved evidence include: - T2 cytokine axis: IL5, IL4, IL13 (as canonical T2 mediators; CVA frequently assessed via eosinophils/FeNO as proxies). (zhu2024bibliometricanalysisof pages 16-18, kim2024couldcoughhypersensitivity pages 2-3) - Eosinophilic biomarkers: eosinophil-related mediators (e.g., ECP as reported in literature summarized by the 2024 bibliometric review). (zhu2024bibliometricanalysisof pages 16-18) - Inflammatory/remodeling-associated factors measured clinically: IL6, IL8, TNF, TGFB1, IgE—all decreased during inhaled budesonide therapy in a 2024 retrospective cohort. (niu2024theeffectsof pages 2-4) - Sensory transduction channels (cough hypersensitivity concept): TRPV1, TRPA1 (implicated in cough reflex sensitivity concepts in asthma/chronic cough literature). (hirons2023coughinchronic pages 2-4)

3.2 Cell types (Cell Ontology, CL)

  • Eosinophils (CL:0000542): elevated in subsets; used for defining T2 inflammation (blood eos ≥300/µL; sputum eos ≥3%). (kim2024couldcoughhypersensitivity pages 2-3)
  • Th2 cells (CL:0000910) and other type 2 immune networks (inferred through T2 inflammation definitions and Th2 framing). (zhu2024bibliometricanalysisof pages 16-18)
  • Airway epithelial cells (CL:0002328): central to airway inflammation and to sensory nerve–epithelium crosstalk in cough hypersensitivity paradigms. (hirons2023coughinchronic pages 2-4)
  • Airway smooth muscle cells (CL:0000297): key effector of AHR.
  • Airway sensory neurons (CL:0000107; vagal afferents/C-fibers conceptually): drivers of cough reflex hypersensitivity. (hirons2023coughinchronic pages 2-4)

3.3 Anatomical locations (UBERON)

  • Lower airway/lung (UBERON:0002048) and bronchial tree: site of AHR and inflammation.
  • Small airways/bronchioles (UBERON:0002186; small airway compartment): implicated by SAD prevalence and the “small airway inflammation” framing for atypical asthma. (han2024smallairwayinflammation pages 1-2, yi2022smallairwaydysfunction pages 1-2)
  • Airway epithelium (UBERON:0000065): interface for inflammatory signaling and cough sensory activation.

4) Biological processes disrupted (GO-style mapping)

The evidence supports disruption in the following GO-relevant biological processes (representative terms): - Type 2 immune response / eosinophil-mediated inflammation (proxied by blood/sputum eosinophilia and FeNO; operationalized diagnostically). (kim2024couldcoughhypersensitivity pages 2-3, lai2022clinicalandinflammatory pages 1-2) - Inflammatory response / cytokine-mediated signaling (IL-6, IL-8, TNF, TGF-β1 changes with ICS treatment). (niu2024theeffectsof pages 2-4) - Airway smooth muscle contraction / response to bronchoconstrictor stimulus (AHR defined by methacholine PC20/PD20). (kim2024couldcoughhypersensitivity pages 2-3, lai2022clinicalandinflammatory pages 1-2) - Sensory perception of chemical stimulus / cough reflex signaling (neuro-immune interaction) (cough reflex hypersensitivity; capsaicin sensitivity). (hirons2023coughinchronic pages 2-4) - Airway remodeling and small-airway functional impairment (SAD persistence; atypical asthma small-airway hypothesis). (han2024smallairwayinflammation pages 1-2, yi2022smallairwaydysfunction pages 1-2)

5) Cellular components (where key processes occur)

Based on the mechanisms above, key cellular compartments include: - Extracellular space and airway lumen (cytokines, eosinophil mediators measured in blood/sputum). - Plasma membrane ion channels on sensory neurons/epithelial cells (TRP channels conceptually implicated in cough reflex sensitivity). (hirons2023coughinchronic pages 2-4) - Airway smooth muscle contractile apparatus (AHR physiology).

6) Disease progression model (sequence of events)

Proposed sequence (evidence-supported skeleton)

  1. Triggers/irritants/allergen-associated airway inflammation occurs with measurable T2 traits in a subset (FeNO/eosinophils), though often lower than classic asthma. (lai2022clinicalandinflammatory pages 1-2, kim2024couldcoughhypersensitivity pages 2-3)
  2. Development of airway hyperresponsiveness demonstrable via methacholine challenge (PC20/PD20 thresholds). (kim2024couldcoughhypersensitivity pages 2-3, lai2022clinicalandinflammatory pages 1-2)
  3. Cough reflex hypersensitivity becomes clinically manifest (triggers, laryngeal sensations; capsaicin sensitivity in asthma), contributing to cough disproportionate to measured eosinophilia or AHR severity. (hirons2023coughinchronic pages 2-4, kim2024couldcoughhypersensitivity pages 2-3, lai2022clinicalandinflammatory pages 1-2)
  4. Small airway dysfunction is common and may persist despite short-term anti-inflammatory therapy, potentially contributing to chronicity and incomplete resolution. (yi2022smallairwaydysfunction pages 1-2, han2024smallairwayinflammation pages 1-2)
  5. In a subset, progression to wheeze/classic asthma is reported in the broader literature; an older synthesis suggests ~30% may progress without treatment over ~3–5 years, with risk reduction by early ICS. (vujnovic2018coughvariantasthma pages 1-3)

Note: High-quality, recent (2023–2024) prospective mechanistic progression estimates were not available in full text within this tool run; the progression statistic above is from older synthesis. (vujnovic2018coughvariantasthma pages 1-3)

7) Phenotypic manifestations (HP terms) and mechanistic links

Key clinical phenotypes

  • Chronic cough (HP:0012735) is the defining manifestation. (kim2024couldcoughhypersensitivity pages 2-3)
  • Airway hyperresponsiveness (physiologic trait reflected by methacholine PC20/PD20). (kim2024couldcoughhypersensitivity pages 2-3, lai2022clinicalandinflammatory pages 1-2)
  • Abnormal laryngopharyngeal sensations (cough hypersensitivity-associated phenotype; reported 71% in CVA vs 51% in classic asthma). (lai2022clinicalandinflammatory pages 1-2)

Mechanistic linkages

  • Disproportionate cough severity with lower eosinophilic markers supports a dual-track model: treatable T2 inflammation (in some patients) plus neuronal cough hypersensitivity. (lai2022clinicalandinflammatory pages 1-2, kim2024couldcoughhypersensitivity pages 2-3, hirons2023coughinchronic pages 2-4)

8) Recent developments (prioritizing 2023–2024)

8.1 Operationalization of “asthmatic cough” with objective treatable traits (2024)

The Korean chronic cough registry work provides an explicit, reproducible framework to classify CVA within chronic cough phenotypes using objective AHR and T2 thresholds plus treatment response confirmation. This supports real-world phenotype stratification and trial enrollment. (kim2024couldcoughhypersensitivity pages 2-3)

8.2 Renewed emphasis on small airway inflammation in atypical asthma (2024)

A 2024 review highlights small-airway inflammation as a likely substrate for atypical asthma manifestations (including CVA), encouraging adoption of approaches that partition central vs peripheral airway inflammation and focus on small airway dysfunction. (han2024smallairwayinflammation pages 1-2)

8.3 Updated synthesis of cough biology in asthma (2023)

A 2023 state-of-the-art review emphasizes cough reflex hypersensitivity as a cross-cutting mechanism in asthma and other chronic lung diseases, with objective measures (capsaicin cough challenge) and emerging cough-targeted therapeutics (e.g., P2X3 antagonism) discussed as part of the evolving framework for chronic cough management. (hirons2023coughinchronic pages 2-4)

9) Current applications and real-world implementations

9.1 Diagnostics / phenotyping in clinical settings

  • Bronchial provocation testing (methacholine PC20/PD20) and FeNO/blood/sputum eosinophils are actively used as objective criteria for asthmatic cough/CVA phenotyping in contemporary registries, reflecting real-world implementation. (kim2024couldcoughhypersensitivity pages 2-3)
  • Comparative biomarker profiling (FeNO, eosinophils, PD20) differentiates CVA from classic asthma in large cohorts and can guide expectations regarding inflammation intensity and AHR. (lai2022clinicalandinflammatory pages 1-2, lai2022clinicalandinflammatory media 8cf72c80)

9.2 Therapeutics

  • Inhaled corticosteroids (ICS) remain foundational anti-inflammatory therapy. A 2024 retrospective study of budesonide reported 56% complete remission and 36% partial remission at 8 weeks, with parallel decreases in systemic inflammatory markers (IL-6, TGF-β1, IgE and others). (niu2024theeffectsof pages 2-4)
  • Treatable traits paradigm: the convergence of cough hypersensitivity features across asthmatic cough and refractory chronic cough suggests that, beyond ICS and bronchodilators, cough-directed approaches may be relevant for selected patients. (kim2024couldcoughhypersensitivity pages 2-3, hirons2023coughinchronic pages 2-4)

10) Relevant statistics and data (recent studies)

Metric Population/study design Numeric result Interpretation Source (year, DOI/URL)
Chronic cough prevalence in asthma State-of-the-art review across cohorts 8–58% Large variability across studies; cough is common in asthma cohorts 2023, 10.21037/jtd-22-1776 (hirons2023coughinchronic pages 1-2)
Small airway dysfunction (SAD) prevalence in CVA Retrospective CVA cohort (n=120), pre-treatment 60.8% SAD is common at baseline in CVA 2022, 10.3389/fphys.2021.761622 (yi2022smallairwaydysfunction pages 1-2)
SAD persistence after 2 months Same CVA cohort, post-treatment (n=105) 54.3% Over half persist with SAD despite clinical improvement 2022, 10.3389/fphys.2021.761622 (yi2022smallairwaydysfunction pages 1-2)
FeNO (ppb), CVA vs classic asthma APAC multicenter baseline cohort 38.5 vs 53 (medians) CVA shows lower T2 inflammation than classic asthma 2022, 10.3389/fmed.2021.807385 (lai2022clinicalandinflammatory pages 1-2)
Blood eosinophils (10^9/L), CVA vs classic asthma APAC multicenter baseline cohort 0.2 vs 0.3 (medians) Lower systemic eosinophilia in CVA 2022, 10.3389/fmed.2021.807385 (lai2022clinicalandinflammatory pages 1-2)
Sputum eosinophils (%), CVA vs classic asthma APAC multicenter baseline cohort 2.3% vs 12.2% (medians) Milder airway eosinophilia in CVA 2022, 10.3389/fmed.2021.807385 (lai2022clinicalandinflammatory pages 1-2)
Methacholine PD20-FEV1 (mg), CVA vs classic asthma APAC multicenter baseline cohort 4.2 vs 0.8 (medians) CVA has milder AHR (higher PD20) 2022, 10.3389/fmed.2021.807385 (lai2022clinicalandinflammatory pages 1-2)
Budesonide response rates in CVA Retrospective CVA cohort (n=200), 8 weeks 56% complete, 36% partial, 8% no remission Majority improve with ICS; early biomarker shifts (IL-6/TGF-β1) track response 2024, 10.2147/ijgm.s455872 (niu2024theeffectsof pages 2-4)
Operational thresholds (2024 registry): FeNO, sputum eos, blood eos, PC20 Prospective chronic cough registry (asthmatic cough incl. CVA/EB) FeNO ≥25 ppb; sputum eos ≥3%; blood eos ≥300/μL; PC20 <16 mg/mL Pragmatic, objective criteria to define asthmatic cough/CVA and verify treatment response 2024, 10.1183/23120541.00260-2024 (kim2024couldcoughhypersensitivity pages 2-3)

Table: Quantitative findings for cough variant asthma (CVA) and asthmatic cough from recent cohorts and reviews, including prevalence, small-airway dysfunction, biomarker differences versus classic asthma, treatment response, and diagnostic thresholds. These data support evidence-based characterization and operationalization of CVA in research and practice.

Key comparative biomarker table image (CVA vs classic asthma) is also available from the APAC cohort (Table 4). (lai2022clinicalandinflammatory media 8cf72c80)

11) Mechanism-to-entity mapping for knowledge base (genes, GO, CL, UBERON, CHEBI)

Mechanistic theme Key genes/proteins (HGNC) Key cell types (CL) Key tissues/anatomy (UBERON) Biomarkers/assays Evidence summary with key numeric data Key source (DOI/URL, year)
Type 2 (T2) eosinophilic inflammation and cytokine milieu IL5 (HGNC:6025); IL4 (HGNC:6014); IL13 (HGNC:5973); IGHE (HGNC:5463) Eosinophil (CL:0000542); Th2 cell (CL:0000910); ILC2 (CL:0001065) Lower airway/lung (UBERON:0002048) FeNO; blood/sputum eosinophils; total IgE; serum cytokines (ELISA) Budesonide therapy in CVA reduced serum IL‑6, IL‑8, TNF‑α, TGF‑β1, IL‑5 and IgE across 2–8 weeks (complete/partial responders showed significantly lower IL‑6/TGF‑β1 at early time points, P<0.05). CVA shows T2-linked mechanisms but often with lower eosinophilic indices than classic asthma (median FeNO 38.5 vs 53 ppb; sputum eos 2.3% vs 12.2%) (niu2024theeffectsof pages 2-4, lai2022clinicalandinflammatory pages 1-2, zhu2024bibliometricanalysisof pages 16-18) 10.2147/ijgm.s455872 (2024); 10.3389/fmed.2021.807385 (2022); 10.2147/jaa.s452097 (2024)
Airway hyperresponsiveness (AHR) and bronchial reactivity — (physiologic trait) Airway smooth muscle cell (CL:0000297); epithelial cells (CL:0002328) Bronchus/bronchioles (UBERON:0002185/0002186) Methacholine PC20/PD20; bronchodilator response AHR central to CVA; registry criteria used PC20 <16 mg/mL and/or objective response to anti-asthma therapy. CVA cohorts show milder AHR than classic asthma (higher PD20), yet AHR associates with wheeze risk (bibliometric synthesis) (kim2024couldcoughhypersensitivity pages 2-3, zhu2024bibliometricanalysisof pages 16-18) 10.1183/23120541.00260-2024 (2024); 10.2147/jaa.s452097 (2024)
Cough reflex hypersensitivity (neuro‑sensory pathway) TRPV1 (HGNC:11320); TRPA1 (HGNC:18012) Sensory neuron (airway/vagal C‑fiber; CL:0000107); airway epithelial cell (CL:0002328) Airway epithelium (UBERON:0000065); lower respiratory tract (UBERON:0001004) Capsaicin cough challenge (C2/C5 thresholds); CHQ (symptom triggers) Asthma/CVA exhibit heightened cough reflex sensitivity: markedly lower capsaicin C5 thresholds vs controls (e.g., ~62.5 vs >500 μM; P<0.001). Symptom profiles of cough hypersensitivity in asthmatic cough (CVA/EB) similar to refractory chronic cough, underscoring shared neuronal treatable trait (hirons2023coughinchronic pages 2-4, hirons2023coughinchronic pages 1-2, kim2024couldcoughhypersensitivity pages 2-3) 10.21037/jtd-22-1776 (2023); 10.1183/23120541.00260-2024 (2024)
Small airway dysfunction (SAD) and peripheral involvement — (structural/functional) Airway epithelial cell (CL:0002328); club cell (CL:0000134) Small airways (UBERON:0005409) Spirometric small‑airway indices (MMEF%pred; FEF50/75%pred) SAD present in 60.8% of corticosteroid‑naïve CVA; persisted in 54.3% after 2 months despite symptom/FeNO/sputum eos improvements; baseline SAD linked to older age, female sex; no baseline FeNO or sputum eos differences vs non‑SAD (yi2022smallairwaydysfunction pages 1-2) 10.3389/fphys.2021.761622 (2022)
Biomarker-defined asthmatic cough/CVA criteria in practice — (panel) Eosinophil (CL:0000542); airway cells Lower airway (UBERON:0002048) FeNO ≥25 ppb; sputum eos ≥3%; blood eos ≥300/μL; PC20 <16 mg/mL Prospective registry operationalized “asthmatic cough” (CVA/EB) with objective T2/AHR thresholds and validated response to anti-asthma therapy at 6 months; provides pragmatic, quantifiable CVA identification framework (kim2024couldcoughhypersensitivity pages 2-3) 10.1183/23120541.00260-2024 (2024)
CVA vs classic asthma inflammatory intensity ECP (PRG2; HGNC:9441, proxy), histamine (HDC; HGNC:4861, proxy) Eosinophil (CL:0000542); mast cell (CL:0000097) Bronchial mucosa (UBERON:0001600) Sputum eosinophils/ECP; FeNO CVA typically shows lower FeNO/blood & sputum eosinophils than classic asthma despite comparable cough burden; APAC cohort: FeNO 38.5 vs 53 ppb; sputum eos 2.3% vs 12.2%; blood eos 0.2 vs 0.3 (10^9/L), all P≤0.002 (lai2022clinicalandinflammatory pages 1-2) 10.3389/fmed.2021.807385 (2022)
Progression risk to classic asthma (wheeze) — (risk construct) — Lower airway (UBERON:0002048) Longitudinal natural history; treatment effect (ICS) Historical/clinical synthesis: without treatment, ~30% of CVA patients may progress to classic asthma with wheeze over ~3–5 years; early ICS associated with reduced progression risk (vujnovic2018coughvariantasthma pages 1-3) 10.5772/intechopen.75152 (2018)
Field consensus on core CVA mechanisms — — Airways/lungs Bibliometric synthesis of focus areas CVA research emphases: airway inflammation (eosinophils/T2), airway hyperresponsiveness, cough hypersensitivity; diagnostic cutoffs reported: FeNO ~48.5 ppb; small airway FEF25–75 ~74.6% aiding identification (zhu2024bibliometricanalysisof pages 16-18) 10.2147/jaa.s452097 (2024)

Table: Key molecular and cellular mechanisms implicated in cough variant asthma, mapped to genes/proteins, cell types, and anatomical sites, with representative biomarkers and quantitative evidence from recent cohorts/reviews. Citations indicate sources for each row and include URLs/DOIs with publication years.

Chemical entities (CHEBI; examples relevant to assays/biology in this evidence set): - Methacholine (CHEBI:???; used in bronchial provocation testing; CHEBI ID not available in current context) (kim2024couldcoughhypersensitivity pages 2-3, lai2022clinicalandinflammatory pages 1-2) - Nitric oxide (NO) (CHEBI:16480; inferred from FeNO measurement context) (kim2024couldcoughhypersensitivity pages 2-3, lai2022clinicalandinflammatory pages 1-2) - Budesonide (CHEBI:??; ICS used in 2024 cohort; CHEBI ID not available in current context) (niu2024theeffectsof pages 2-4)

12) Expert opinion / analysis (authoritative synthesis)

The aggregate evidence supports an expert-level interpretation that CVA is not merely “mild asthma with cough,” but rather a phenotype characterized by: 1. Milder average T2 biomarker elevation and AHR severity than classic asthma, yet severe cough burden and frequent laryngopharyngeal sensations (suggesting additional mechanisms beyond eosinophilia/AHR magnitude). (lai2022clinicalandinflammatory pages 1-2) 2. Cough reflex hypersensitivity as a shared mechanistic substrate across chronic cough phenotypes, including asthmatic cough, motivating treatable-traits frameworks. (kim2024couldcoughhypersensitivity pages 2-3, hirons2023coughinchronic pages 2-4) 3. High prevalence of small airway dysfunction, which can persist despite short-term anti-asthma therapy and may represent an under-addressed contributor to persistent symptoms and relapse risk. (yi2022smallairwaydysfunction pages 1-2, han2024smallairwayinflammation pages 1-2)

13) Evidence items (PMIDs)

Limitation: The retrieved tool evidence in this run provided DOIs/URLs and detailed numeric results, but PMIDs were not present in the extracted snippets for most items. Therefore, I cannot reliably attach PMID identifiers without risking citation error. Key evidence items are therefore listed with DOI/URL and publication date: - Kim et al., ERJ Open Research, Jun 2024. https://doi.org/10.1183/23120541.00260-2024 (kim2024couldcoughhypersensitivity pages 2-3) - Han et al., Heliyon, Sep 2024. https://doi.org/10.1016/j.heliyon.2024.e36124 (han2024smallairwayinflammation pages 1-2) - Hirons et al., Journal of Thoracic Disease, Oct 2023. https://doi.org/10.21037/jtd-22-1776 (hirons2023coughinchronic pages 1-2, hirons2023coughinchronic pages 2-4) - Zhu et al., Journal of Asthma and Allergy, Jun 2024. https://doi.org/10.2147/JAA.S452097 (zhu2024bibliometricanalysisof pages 16-18) - Niu et al., International Journal of General Medicine, Mar 2024. https://doi.org/10.2147/IJGM.S455872 (niu2024theeffectsof pages 2-4) - Lai et al., Frontiers in Medicine, Jan 2022. https://doi.org/10.3389/fmed.2021.807385 (lai2022clinicalandinflammatory pages 1-2, lai2022clinicalandinflammatory media 8cf72c80) - Yi et al., Frontiers in Physiology, Jan 2022. https://doi.org/10.3389/fphys.2021.761622 (yi2022smallairwaydysfunction pages 1-2)

Appendix: Visual evidence

  • Comparative CVA vs classic asthma biomarker and lung function table (FeNO, blood/sputum eosinophils, PD20-FEV1): (lai2022clinicalandinflammatory media 8cf72c80)

References

  1. (kim2024couldcoughhypersensitivity pages 2-3): Mi-Yeong Kim, Ha-Kyeong Won, Ji-Yoon Oh, Ji-Hyang Lee, Eun-Jung Jo, Sung-Yoon Kang, Ji-Ho Lee, Seung-Eun Lee, Noeul Kang, Young-Chan Kim, Hwa Young Lee, Jin An, Youngsang Yoo, Ji-Su Shim, So-Young Park, Han-Ki Park, Min-Hye Kim, Sae-Hoon Kim, Sang-Heon Kim, Yoon-Seok Chang, Sang-Hoon Kim, Byung-Jae Lee, Surinder S. Birring, and Woo-Jung Song. Could cough hypersensitivity symptom profile differentiate phenotypes of chronic cough? ERJ Open Research, 10:00260-2024, Jun 2024. URL: https://doi.org/10.1183/23120541.00260-2024, doi:10.1183/23120541.00260-2024. This article has 14 citations and is from a peer-reviewed journal.

  2. (han2024smallairwayinflammation pages 1-2): Junjie Han, Li Li, Ying Gong, Juan Song, Yichun Zhu, Cuicui Chen, Lin Shi, Jian Wang, Yuanlin Song, and Jun She. Small airway inflammation in atypical asthma. Sep 2024. URL: https://doi.org/10.1016/j.heliyon.2024.e36124, doi:10.1016/j.heliyon.2024.e36124. This article has 3 citations.

  3. (lai2022clinicalandinflammatory pages 1-2): Kefang Lai, Wenzhi Zhan, Feng Wu, Yunhui Zhang, Lin Lin, Wen Li, Fang Yi, Ziyu Jiang, Yuanrong Dai, Suyun Li, Jiangtao Lin, Yadong Yuan, Yong Jiang, Chen Qiu, Limin Zhao, Meihua Chen, Zhongmin Qiu, Hu Li, Ruchong Chen, Wei Luo, Jiaxing Xie, Chunxing Guo, Mei Jiang, Xiaohong Yang, Guochao Shi, Dejun Sun, Rongchang Chen, Kian Fan Chung, Huahao Shen, and Nanshan Zhong. Clinical and inflammatory characteristics of the chinese apac cough variant asthma cohort. Frontiers in Medicine, Jan 2022. URL: https://doi.org/10.3389/fmed.2021.807385, doi:10.3389/fmed.2021.807385. This article has 28 citations.

  4. (zhu2024bibliometricanalysisof pages 16-18): Ziyu Zhu, Jiabao Wu, Wenjun Chen, Fei Luo, and Xia Zhao. Bibliometric analysis of cough variant asthma from 1993 to 2022. Journal of Asthma and Allergy, 17:517-537, Jun 2024. URL: https://doi.org/10.2147/jaa.s452097, doi:10.2147/jaa.s452097. This article has 6 citations and is from a peer-reviewed journal.

  5. (hirons2023coughinchronic pages 2-4): Barnaby Hirons, Katherine Rhatigan, Harini Kesavan, Richard D. Turner, Surinder S. Birring, and Peter S. P. Cho. Cough in chronic lung disease: a state of the art review. Journal of Thoracic Disease, 15:5823-5843, Oct 2023. URL: https://doi.org/10.21037/jtd-22-1776, doi:10.21037/jtd-22-1776. This article has 34 citations and is from a peer-reviewed journal.

  6. (yi2022smallairwaydysfunction pages 1-2): Fang Yi, Ziyu Jiang, Hu Li, Chunxing Guo, Hankun Lu, Wei Luo, Qiaoli Chen, and Kefang Lai. Small airway dysfunction in cough variant asthma: prevalence, clinical, and pathophysiological features. Frontiers in Physiology, Jan 2022. URL: https://doi.org/10.3389/fphys.2021.761622, doi:10.3389/fphys.2021.761622. This article has 30 citations.

  7. (niu2024theeffectsof pages 2-4): Yueying Niu, Mengqing Cao, Shumin Li, Juanfen Mo, Ziyi Zhu, and Haiqin Wang. The effects of budesonide inhalation treatment on the expression levels of serum il-6, tgf-β1, and ige and pulmonary function in patients with cough variant asthma and an evaluation of treatment efficacy. International Journal of General Medicine, 17:1253-1261, Mar 2024. URL: https://doi.org/10.2147/ijgm.s455872, doi:10.2147/ijgm.s455872. This article has 6 citations.

  8. (vujnovic2018coughvariantasthma pages 1-3): Sanela Domuz Vujnović, Adrijana Domuz, and Slobodanka Petrović. Cough variant asthma as a phenotype of classic asthma. Asthma Diagnosis and Management - Approach Based on Phenotype and Endotype, Jul 2018. URL: https://doi.org/10.5772/intechopen.75152, doi:10.5772/intechopen.75152. This article has 3 citations.

  9. (lai2022clinicalandinflammatory media 8cf72c80): Kefang Lai, Wenzhi Zhan, Feng Wu, Yunhui Zhang, Lin Lin, Wen Li, Fang Yi, Ziyu Jiang, Yuanrong Dai, Suyun Li, Jiangtao Lin, Yadong Yuan, Yong Jiang, Chen Qiu, Limin Zhao, Meihua Chen, Zhongmin Qiu, Hu Li, Ruchong Chen, Wei Luo, Jiaxing Xie, Chunxing Guo, Mei Jiang, Xiaohong Yang, Guochao Shi, Dejun Sun, Rongchang Chen, Kian Fan Chung, Huahao Shen, and Nanshan Zhong. Clinical and inflammatory characteristics of the chinese apac cough variant asthma cohort. Frontiers in Medicine, Jan 2022. URL: https://doi.org/10.3389/fmed.2021.807385, doi:10.3389/fmed.2021.807385. This article has 28 citations.

  10. (hirons2023coughinchronic pages 1-2): Barnaby Hirons, Katherine Rhatigan, Harini Kesavan, Richard D. Turner, Surinder S. Birring, and Peter S. P. Cho. Cough in chronic lung disease: a state of the art review. Journal of Thoracic Disease, 15:5823-5843, Oct 2023. URL: https://doi.org/10.21037/jtd-22-1776, doi:10.21037/jtd-22-1776. This article has 34 citations and is from a peer-reviewed journal.