The prevalence of pulmonary hypertension in patients with obesity hypoventilation syndrome: a prospective observational study

Background: One important cardiovascular morbidity that is associated with obesity hypoventilation syndrome (OHS) is the development of pulmonary hypertension (PH). However, few studies have assessed PH in OHS patients. Therefore, we prospectively assessed the prevalence of PH in a large sample of OHS patients. Methods: In this prospective observational study, all consecutive OHS patients referred to the sleep disorders clinic during the study period were included. All patients underwent overnight polysomnography (PSG), spirometry, arterial blood samples and thyroid tests. Transthoracic echocardiography was performed for patients who agreed to participate in the study. PH was defined as systolic pulmonary artery pressure (SPAP) >40 mmHg. Results: Echocardiographic data were available for 77 patients with a mean age of 60.5 +/- 11.7 years, a BMI of 43.2 +/- 10.4 kg/m(2), and an Epworth Sleepiness Scale (ESS) score of 11.4 +/- 5.5. SPAP was >40 mmHg in 53 patients (68.8%), with a mean SPAP of 64.1 +/- 17.1 mmHg. There were no differences between the OHS patients with PH and those with normal PAP in terms of age, BMI, presenting symptoms, comorbidities, arterial blood gasses (ABG), and spirometric and PSG parameters. Approximately 71.4% of women and 61.9% of men with OHS also had PH. SPAP was >40-55 mmHg in 19 (24.7%) patients (18 women), >55-70 mmHg in 15 (19.5%) patients (6 women) and >70 mmHg in 19 (24.7%) patients (16 women). Severe PH (SPAP >70 mmHg) was diagnosed in 28.6% of the women and 14.3% of the men. Conclusions: PH is very common among patients with OHS who have been referred to sleep disorders clinics. PH should be considered in the regular clinical assessment of all patients with OHS.