Obstructive sleep apnea (OSA) is common in all patients with pulmonary hypertension (PH) and is especially prevalent and severe in those with PH due to left-sided heart disease — categorized by the World Health Organization (WHO) as having group II PH – who experience a median of 12 sleep events per hour.  These are among study findings published in BMJ Open Respiratory Research.

Comorbid OSA is recognized as a common condition among patients with PH, although its prevalence has yet to be characterized. Researchers therefore conducted a study comparing the severity and prevalence of OSA among patients in the 5 WHO PH groups.  The investigators hypothesized that the greatest prevalence and severity of OSA would be found in WHO PH group II, the most common PH group, which includes patients with cardiac disease and associated metabolic syndrome.

The researchers initiated a retrospective cohort study of 132 patients with PH (confirmed via right heart catheterization) who had undergone polysomnography or home sleep studies at a tertiary care center in New York between 2000 and 2019. The median apnea hypopnea index (AHI) or the respiratory event index (REI) were used to measure OSA prevalence and severity. The association between OSA prevalence and severity (ie, AHI and REI scores) and WHO PH group was evaluated.

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The researchers found OSA was common in all 5 WHO pulmonary hypertension groups and most common and most severe in patients with WHO group II PH. The analysis found a median 12.0 events per hour for WHO group II (n=53), compared with 10.0 events/hours in group IV (n=13); 6.4 events/hour in group V (n=4); 3.7 events/hour in group III (n=13); and 2.8 events/hour in group I (n=49).  There was approximately a twofold increase in AHI or REI in WHO group II vs WHO group I pulmonary hypertension as shown by multivariable negative binomial regression.

Study limitations include the retrospective design; the inability to quantify patients using supplemental oxygen during sleep studies; the inclusion of 49 patients who underwent home sleep studies instead of polysomnography (the greatest proportion of which were patients with WHO group II pulmonary hypertension); unequal and underpowered sample sizes for WHO groups III, IV, and V.

Researchers concluded that “OSA deserves greater consideration as a treatable comorbidity that may affect pulmonary hemodynamics and quality of life in patients with pulmonary hypertension across all WHO groups.”


Simonson JL, Pandya D, Khan S, Greenberg HE, Talwar A. Comparison of obstructive sleep apnoea prevalence and severity across WHO pulmonary hypertension groups. BMJ Open Respir Res. August 2022;9(1):e001304. doi:10.1136/bmjresp-2022-001304