Obstructive Sleep Apnea <-> Secondary Hypertension

Comorbidity A_BEFORE_B CANDIDATE

Side B is `Secondary_Hypertension`, not `Essential_Hypertension`. That is a deliberate nosological choice: `kb/disorders/Secondary_Hypertension.yaml` already names obstructive sleep apnea among the identifiable causes whose shared final common path is raised blood pressure, so hypertension driven by OSA is by definition secondary, and pairing OSA with essential (idiopathic) hypertension would contradict the KB's own definition of both entries. The practical caveat is that this boundary is cleaner in the ontology than in the clinic. Most OSA patients who become hypertensive are coded as having essential hypertension because the apnea is never diagnosed, so population-level studies of "hypertension" in OSA — including the Wisconsin Sleep Cohort signal recorded below — are measuring incident hypertension without regard to that distinction. The signal is therefore quantitatively about hypertension in general and is mapped here to the secondary entity on mechanistic grounds. Directionality is A_BEFORE_B. The dose-response cohort measures blood pressure years after polysomnography, and the CPAP trials show the blood pressure falls when the apnea is treated — evidence that the ordering is causal rather than an artifact of shared adiposity.

Disease A

Obstructive Sleep Apnea

Slug:Obstructive_Sleep_Apnea

Disease B

Secondary Hypertension

Slug:Secondary_Hypertension

Causal Mechanism Graphs

Obstructive Sleep Apnea

graph LR
    Sleep_Fragmentation["Sleep Fragmentation"]
    MAPK_Cascade_Activation["MAPK Cascade Activation"]
    NLRP3_Inflammasome_Activation["NLRP3 Inflammasome Activation"]
    Ocular_Surface_Inflammation_and_Dry_Eye_Disease["Ocular Surface Inflammation and Dry Eye Disease"]
    CPAP["CPAP"]
    Non_Anatomic_Endotypic_Traits["Non-Anatomic Endotypic Traits"]
    Sympathetic_Overactivation["Sympathetic Overactivation"]
    Intermittent_Hypoxia["Intermittent Hypoxia"]
    Systemic_Inflammation["Systemic Inflammation"]
    TLR4_Upregulation["TLR4 Upregulation"]
    Upper_Airway_Collapse["Upper Airway Collapse"]
    MyD88_Dependent_NF_κB_Activation["MyD88-Dependent NF-κB Activation"]

    Upper_Airway_Collapse --> Sleep_Fragmentation
    Upper_Airway_Collapse --> Intermittent_Hypoxia
    Intermittent_Hypoxia --> TLR4_Upregulation
    Intermittent_Hypoxia --> Sympathetic_Overactivation
    Intermittent_Hypoxia --> Systemic_Inflammation
    Intermittent_Hypoxia --> Ocular_Surface_Inflammation_and_Dry_Eye_Disease
    TLR4_Upregulation --> MyD88_Dependent_NF_κB_Activation
    TLR4_Upregulation --> MAPK_Cascade_Activation
    MyD88_Dependent_NF_κB_Activation --> Systemic_Inflammation
    MyD88_Dependent_NF_κB_Activation --> NLRP3_Inflammasome_Activation
    MAPK_Cascade_Activation --> Systemic_Inflammation
    Sleep_Fragmentation --> Intermittent_Hypoxia
    Non_Anatomic_Endotypic_Traits --> Sleep_Fragmentation
    Non_Anatomic_Endotypic_Traits --> Upper_Airway_Collapse
    NLRP3_Inflammasome_Activation --> Systemic_Inflammation
    CPAP --> Sleep_Fragmentation
    CPAP --> Upper_Airway_Collapse

    style Sleep_Fragmentation fill:#dbeafe
    style MAPK_Cascade_Activation fill:#dbeafe
    style NLRP3_Inflammasome_Activation fill:#dbeafe
    style Ocular_Surface_Inflammation_and_Dry_Eye_Disease fill:#dbeafe
    style CPAP fill:#fce7f3
    style Non_Anatomic_Endotypic_Traits fill:#dbeafe
    style Sympathetic_Overactivation fill:#dbeafe
    style Intermittent_Hypoxia fill:#dbeafe
    style Systemic_Inflammation fill:#dbeafe
    style TLR4_Upregulation fill:#dbeafe
    style Upper_Airway_Collapse fill:#dbeafe
    style MyD88_Dependent_NF_κB_Activation fill:#dbeafe

Secondary Hypertension

graph LR
    Sympathetic_and_hormonal_coactivation["Sympathetic and hormonal coactivation"]
    VEGF_Pathway_Inhibitor_Exposure["VEGF Pathway Inhibitor Exposure"]
    Endothelial_Nitric_Oxide_Deficiency_and_Oxidative_Stress["Endothelial Nitric Oxide Deficiency and Oxidative Stress"]
    Calcium_Channel_Blocker["Calcium Channel Blocker"]
    Drug_Induced_Vasoconstriction_and_Increased_Peripheral_Vascular_Resistance["Drug-Induced Vasoconstriction and Increased Peripheral Vascular Resistance"]
    Microvascular_Rarefaction["Microvascular Rarefaction"]
    Endothelin_1_System_Activation["Endothelin-1 System Activation"]
    Renin_Angiotensin_System_Inhibition_ACE_Inhibitor_or_ARB["Renin-Angiotensin System Inhibition (ACE Inhibitor or ARB)"]
    Hypertension["Hypertension"]

    Sympathetic_and_hormonal_coactivation --> Hypertension
    VEGF_Pathway_Inhibitor_Exposure --> Endothelial_Nitric_Oxide_Deficiency_and_Oxidative_Stress
    VEGF_Pathway_Inhibitor_Exposure --> Endothelin_1_System_Activation
    VEGF_Pathway_Inhibitor_Exposure --> Microvascular_Rarefaction
    Endothelial_Nitric_Oxide_Deficiency_and_Oxidative_Stress --> Drug_Induced_Vasoconstriction_and_Increased_Peripheral_Vascular_Resistance
    Endothelin_1_System_Activation --> Drug_Induced_Vasoconstriction_and_Increased_Peripheral_Vascular_Resistance
    Microvascular_Rarefaction --> Drug_Induced_Vasoconstriction_and_Increased_Peripheral_Vascular_Resistance
    Drug_Induced_Vasoconstriction_and_Increased_Peripheral_Vascular_Resistance --> Hypertension
    Renin_Angiotensin_System_Inhibition_ACE_Inhibitor_or_ARB --> Drug_Induced_Vasoconstriction_and_Increased_Peripheral_Vascular_Resistance
    Calcium_Channel_Blocker --> Drug_Induced_Vasoconstriction_and_Increased_Peripheral_Vascular_Resistance

    style Sympathetic_and_hormonal_coactivation fill:#dbeafe
    style VEGF_Pathway_Inhibitor_Exposure fill:#dbeafe
    style Endothelial_Nitric_Oxide_Deficiency_and_Oxidative_Stress fill:#dbeafe
    style Calcium_Channel_Blocker fill:#fce7f3
    style Drug_Induced_Vasoconstriction_and_Increased_Peripheral_Vascular_Resistance fill:#dbeafe
    style Microvascular_Rarefaction fill:#dbeafe
    style Endothelin_1_System_Activation fill:#dbeafe
    style Renin_Angiotensin_System_Inhibition_ACE_Inhibitor_or_ARB fill:#fce7f3
    style Hypertension fill:#fef3c7

Association Signals

Signal 1

Population:Wisconsin Sleep Cohort Study, 709 participants assessed by 18-channel polysomnography at baseline and re-assessed for hypertension after four years (184 also at eight years); odds ratios adjusted for baseline hypertension, body-mass index, neck and waist circumference, age, sex, alcohol and cigarette use.

Mapping notes:The cohort measures hypertension as blood pressure >=140/90 mm Hg or antihypertensive use, without separating essential from secondary hypertension; see the entry notes on why the mechanistic mapping is to the secondary entity.

Temporal: A before B: , B before A: , Same time:

AOR: 2.03

CI: 1.29 - 3.17

FDR:

Hypertension at four-year follow-up for a baseline apnea-hypopnea index of 5.0-14.9 events/hour versus 0 events/hour.

AOR: 2.89

CI: 1.46 - 5.64

FDR:

Same comparison for a baseline apnea-hypopnea index of 15.0 or more events/hour. The rise across strata is the dose-response the authors report.

PMID:10805822 (SUPPORT)

Source: HUMAN_CLINICAL

"the odds ratios for the presence of hypertension at follow-up were 1.42 (95 percent confidence interval, 1.13 to 1.78) with an apnea-hypopnea index of 0.1 to 4.9 events per hour at base line as compared with none, 2.03 (95 percent confidence interval, 1.29 to 3.17)"

Reports the graded odds of incident hypertension by baseline apnea-hypopnea index in a population followed forward.

PMID:10805822 (SUPPORT)

Source: HUMAN_CLINICAL

"We found a dose-response association between sleep-disordered breathing at base line and the presence of hypertension four years later that was independent of known confounding factors."

States the dose-response and its independence of measured confounders, which is what supports the directed A_BEFORE_B reading.

Hypotheses

Repetitive nocturnal airway obstruction produces chronic intermittent hypoxia, which sensitizes the carotid body chemoreflex. The sensitized chemoreflex drives sympathetic outflow that persists into daytime wakefulness, so a disorder confined to sleep raises blood pressure around the clock. Systemic inflammation and oxidative stress accompany the autonomic effect.

PMID:42600231 (SUPPORT, review synthesis)

Source: OTHER

"The CIH contributes to these adverse outcomes by enhancing carotid body chemoreceptor sensitivity and promoting sympathetic overactivation, systemic inflammation, and oxidative stress."

States the mechanistic chain from chronic intermittent hypoxia through carotid body sensitization to sympathetic overactivation.

PMID:42600231 (SUPPORT, review synthesis)

Source: HUMAN_CLINICAL

"OSA is recognized as an independent risk factor for systemic hypertension and is associated with cardiac arrhythmias and stroke."

Supports treating OSA as an independent antecedent risk state for systemic hypertension rather than a co-finding.

Pathophysiology:

Chronic intermittent hypoxia-driven chemoreflex sensitization: Cyclical desaturation and reoxygenation during obstructive events sensitizes carotid body glomus cells, raising sympathetic tone and systemic arterial pressure.

Biological processes:

PMID:39844350 (SUPPORT)

Source: MODEL_ORGANISM

"These results demonstrate that Adcy3-dependent cAMP is a downstream signaling pathway to H2S/Olfr78, mediating CIH-induced CB activation, sympathetic activity and hypertension."

Null-mouse dissection of the carotid body signaling pathway shows the hypertensive response to intermittent hypoxia requires chemoreceptor activation, establishing the step as necessary rather than merely correlated. Rodent evidence for the mechanism; the human ordering rests on the cohort and CPAP evidence in this entry.

If sleep-disordered breathing is what raises the blood pressure, abolishing the obstructive events should lower it. Randomized trials of CPAP in hypertensive OSA patients show exactly that, with a modest average ambulatory reduction that is larger at night than during the day — the pattern expected if the driver is a nocturnal stimulus — and larger still in resistant hypertension. The effect size is small in absolute terms, so CPAP corroborates the causal direction without making OSA the sole determinant of the blood pressure.

PMID:25582849 (SUPPORT)

Source: HUMAN_CLINICAL

"CPAP was associated with significant reductions in 24-hour ambulatory systolic blood pressure (SBP) (-2.32 mm Hg; 95% confidence interval [CI], -3.65 to -1.00) and diastolic blood pressure (DBP) (-1.98 mm Hg; 95% CI, -2.82 to -1.14)."

Randomized-trial evidence that removing the obstructive events lowers blood pressure, supporting a causal reading of the association.

PMID:25582849 (SUPPORT)

Source: HUMAN_CLINICAL

"CPAP led to more significant improvement in nocturnal SBP than that in diurnal SBP."

The night-weighted response matches a nocturnal driver, which is the pattern the intermittent-hypoxia mechanism predicts.

Shared Upstream Hypotheses

Upstream:{'slug': 'Obesity', 'preferred_term': 'obesity disorder', 'term': {'id': 'MONDO:0011122', 'label': 'obesity disorder'}}

Obesity is a major cause of both upper-airway collapsibility and hypertension, so some of the observed co-occurrence is confounding rather than a direct OSA-to-hypertension effect. The Wisconsin Sleep Cohort analysis addresses this directly: the dose-response persisted after adjustment for body-mass index and for neck and waist circumference. This argues adiposity does not account for the whole association, but it does not exclude a residual shared-upstream contribution.

PMID:10805822 (SUPPORT, indirect)

Source: HUMAN_CLINICAL

"We found a dose-response association between sleep-disordered breathing at base line and the presence of hypertension four years later that was independent of known confounding factors."

The authors' conclusion that the dose-response persisted independently of known confounders. The confounders their methods adjusted for include body-mass index and neck and waist circumference, the adiposity measures most likely to act as the shared upstream cause, so the persistence weakens but does not eliminate the confounding explanation. Indirect because residual confounding by adiposity is inferred to be limited rather than measured.

Raw YAML

Show YAML

name: com_Obstructive_Sleep_Apnea__Secondary_Hypertension
creation_date: "2026-08-27T00:00:00Z"
curation_status: CANDIDATE
notes: >-
  Side B is `Secondary_Hypertension`, not `Essential_Hypertension`. That is a
  deliberate nosological choice: `kb/disorders/Secondary_Hypertension.yaml`
  already names obstructive sleep apnea among the identifiable causes whose
  shared final common path is raised blood pressure, so hypertension driven by
  OSA is by definition secondary, and pairing OSA with essential (idiopathic)
  hypertension would contradict the KB's own definition of both entries.

  The practical caveat is that this boundary is cleaner in the ontology than in
  the clinic. Most OSA patients who become hypertensive are coded as having
  essential hypertension because the apnea is never diagnosed, so
  population-level studies of "hypertension" in OSA — including the Wisconsin
  Sleep Cohort signal recorded below — are measuring incident hypertension
  without regard to that distinction. The signal is therefore quantitatively
  about hypertension in general and is mapped here to the secondary entity on
  mechanistic grounds.

  Directionality is A_BEFORE_B. The dose-response cohort measures blood
  pressure years after polysomnography, and the CPAP trials show the blood
  pressure falls when the apnea is treated — evidence that the ordering is
  causal rather than an artifact of shared adiposity.

disease_a:
  slug: Obstructive_Sleep_Apnea
  preferred_term: obstructive sleep apnea syndrome
  term:
    id: MONDO:0007147
    label: obstructive sleep apnea syndrome

disease_b:
  slug: Secondary_Hypertension
  preferred_term: secondary hypertension
  term:
    id: MONDO:0001200
    label: secondary hypertension

directionality: A_BEFORE_B
effect_direction: RISK

hypotheses:
- description: >-
    Repetitive nocturnal airway obstruction produces chronic intermittent
    hypoxia, which sensitizes the carotid body chemoreflex. The sensitized
    chemoreflex drives sympathetic outflow that persists into daytime
    wakefulness, so a disorder confined to sleep raises blood pressure around
    the clock. Systemic inflammation and oxidative stress accompany the
    autonomic effect.
  evidence:
  - reference: PMID:42600231
    reference_title: "Syncope and obstructive sleep apnea: Mechanisms and clinical scenarios."
    supports: SUPPORT
    quote_role: REVIEW_SYNTHESIS
    evidence_source: OTHER
    snippet: "The CIH contributes to these adverse outcomes by enhancing carotid body chemoreceptor sensitivity and promoting sympathetic overactivation, systemic inflammation, and oxidative stress."
    explanation: >-
      States the mechanistic chain from chronic intermittent hypoxia through
      carotid body sensitization to sympathetic overactivation.
  - reference: PMID:42600231
    reference_title: "Syncope and obstructive sleep apnea: Mechanisms and clinical scenarios."
    supports: SUPPORT
    quote_role: REVIEW_SYNTHESIS
    evidence_source: HUMAN_CLINICAL
    snippet: "OSA is recognized as an independent risk factor for systemic hypertension and is associated with cardiac arrhythmias and stroke."
    explanation: >-
      Supports treating OSA as an independent antecedent risk state for
      systemic hypertension rather than a co-finding.
  pathophysiology:
  - name: Chronic intermittent hypoxia-driven chemoreflex sensitization
    description: >-
      Cyclical desaturation and reoxygenation during obstructive events
      sensitizes carotid body glomus cells, raising sympathetic tone and
      systemic arterial pressure.
    biological_processes:
    - preferred_term: response to hypoxia
      term:
        id: GO:0001666
        label: response to hypoxia
    evidence:
    - reference: PMID:39844350
      reference_title: Signal Transduction Pathway Mediating Carotid Body Dependent Sympathetic Activation and Hypertension by Chronic Intermittent Hypoxia.
      supports: SUPPORT
      evidence_source: MODEL_ORGANISM
      snippet: "These results demonstrate that Adcy3-dependent cAMP is a downstream signaling pathway to H2S/Olfr78, mediating CIH-induced CB activation, sympathetic activity and hypertension."
      explanation: >-
        Null-mouse dissection of the carotid body signaling pathway shows the
        hypertensive response to intermittent hypoxia requires chemoreceptor
        activation, establishing the step as necessary rather than merely
        correlated. Rodent evidence for the mechanism; the human ordering rests
        on the cohort and CPAP evidence in this entry.

- description: >-
    If sleep-disordered breathing is what raises the blood pressure, abolishing
    the obstructive events should lower it. Randomized trials of CPAP in
    hypertensive OSA patients show exactly that, with a modest average
    ambulatory reduction that is larger at night than during the day — the
    pattern expected if the driver is a nocturnal stimulus — and larger still
    in resistant hypertension. The effect size is small in absolute terms, so
    CPAP corroborates the causal direction without making OSA the sole
    determinant of the blood pressure.
  evidence:
  - reference: PMID:25582849
    reference_title: "The role of continuous positive airway pressure in blood pressure control for patients with obstructive sleep apnea and hypertension: a meta-analysis of randomized controlled trials."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "CPAP was associated with significant reductions in 24-hour ambulatory systolic blood pressure (SBP) (-2.32 mm Hg; 95% confidence interval [CI], -3.65 to -1.00) and diastolic blood pressure (DBP) (-1.98 mm Hg; 95% CI, -2.82 to -1.14)."
    explanation: >-
      Randomized-trial evidence that removing the obstructive events lowers
      blood pressure, supporting a causal reading of the association.
  - reference: PMID:25582849
    reference_title: "The role of continuous positive airway pressure in blood pressure control for patients with obstructive sleep apnea and hypertension: a meta-analysis of randomized controlled trials."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "CPAP led to more significant improvement in nocturnal SBP than that in diurnal SBP."
    explanation: >-
      The night-weighted response matches a nocturnal driver, which is the
      pattern the intermittent-hypoxia mechanism predicts.

shared_upstream_hypotheses:
- upstream_disorder:
    slug: Obesity
    preferred_term: obesity disorder
    term:
      id: MONDO:0011122
      label: obesity disorder
  description: >-
    Obesity is a major cause of both upper-airway collapsibility and
    hypertension, so some of the observed co-occurrence is confounding rather
    than a direct OSA-to-hypertension effect. The Wisconsin Sleep Cohort
    analysis addresses this directly: the dose-response persisted after
    adjustment for body-mass index and for neck and waist circumference. This
    argues adiposity does not account for the whole association, but it does
    not exclude a residual shared-upstream contribution.
  evidence:
  - reference: PMID:10805822
    reference_title: Prospective study of the association between sleep-disordered breathing and hypertension.
    supports: SUPPORT
    directness: INDIRECT
    evidence_source: HUMAN_CLINICAL
    snippet: "We found a dose-response association between sleep-disordered breathing at base line and the presence of hypertension four years later that was independent of known confounding factors."
    explanation: >-
      The authors' conclusion that the dose-response persisted independently of
      known confounders. The confounders their methods adjusted for include
      body-mass index and neck and waist circumference, the adiposity measures
      most likely to act as the shared upstream cause, so the persistence
      weakens but does not eliminate the confounding explanation. Indirect
      because residual confounding by adiposity is inferred to be limited
      rather than measured.

association_signals:
- source: LITERATURE
  method: LITERATURE_ASSOCIATION
  population: >-
    Wisconsin Sleep Cohort Study, 709 participants assessed by 18-channel
    polysomnography at baseline and re-assessed for hypertension after four
    years (184 also at eight years); odds ratios adjusted for baseline
    hypertension, body-mass index, neck and waist circumference, age, sex,
    alcohol and cigarette use.
  directionality: A_BEFORE_B
  effect_direction: RISK
  mapping_notes: >-
    The cohort measures hypertension as blood pressure >=140/90 mm Hg or
    antihypertensive use, without separating essential from secondary
    hypertension; see the entry notes on why the mechanistic mapping is to the
    secondary entity.
  statistics:
    metrics:
    - metric_type: AOR
      metric_value: 2.03
      metric_ci_lower: 1.29
      metric_ci_upper: 3.17
      notes: >-
        Hypertension at four-year follow-up for a baseline apnea-hypopnea index
        of 5.0-14.9 events/hour versus 0 events/hour.
    - metric_type: AOR
      metric_value: 2.89
      metric_ci_lower: 1.46
      metric_ci_upper: 5.64
      notes: >-
        Same comparison for a baseline apnea-hypopnea index of 15.0 or more
        events/hour. The rise across strata is the dose-response the authors
        report.
    evidence:
    - reference: PMID:10805822
      reference_title: Prospective study of the association between sleep-disordered breathing and hypertension.
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: "the odds ratios for the presence of hypertension at follow-up were 1.42 (95 percent confidence interval, 1.13 to 1.78) with an apnea-hypopnea index of 0.1 to 4.9 events per hour at base line as compared with none, 2.03 (95 percent confidence interval, 1.29 to 3.17)"
      explanation: >-
        Reports the graded odds of incident hypertension by baseline
        apnea-hypopnea index in a population followed forward.
    - reference: PMID:10805822
      reference_title: Prospective study of the association between sleep-disordered breathing and hypertension.
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: "We found a dose-response association between sleep-disordered breathing at base line and the presence of hypertension four years later that was independent of known confounding factors."
      explanation: >-
        States the dose-response and its independence of measured confounders,
        which is what supports the directed A_BEFORE_B reading.

Source:GitHub