Comparison of obstructive sleep apnoea prevalence and severity across WHO pulmonary hypertension groups.

Introduction: Pulmonary hypertension is classified into five groups in the WHO classification system. Patients with pulmonary hypertension often have comorbid obstructive sleep apnoea (OSA), yet the prevalence and severity of OSA in each of the WHO pulmonary hypertension groups have not been well established.

Methods: To compare the prevalence and severity of OSA between WHO pulmonary hypertension groups, we performed a retrospective cohort study, including patients who had polysomnography or a home sleep study and confirmed pulmonary hypertension on right heart catheterisation. The primary outcomes of OSA prevalence and severity were measured by median apnoea hypopnea index (AHI) or respiratory event index (REI) and were compared by WHO pulmonary hypertension group. Multivariable negative binomial regression was used to evaluate the association between the outcome of OSA severity by AHI or REI and WHO group.

Results: Among the cohort of 132 patients, OSA was common in all WHO pulmonary hypertension groups but was most common and most severe in WHO group II pulmonary hypertension. Median AHI or REI in WHO group II was 12.0 events/hour compared with 2.8 in group I, 3.7 in group III, 10.0 in group IV and 6.4 in group V. Multivariable negative binomial regression showed about a twofold increase in AHI or REI in WHO group II compared with WHO group I pulmonary hypertension.

Discussion: Our findings demonstrate that OSA deserves greater consideration as a treatable comorbidity that may affect pulmonary haemodynamics and quality of life in patients with pulmonary hypertension across all WHO groups.