Prevalence, clinical characteristics, and predictors of obesity hypoventilation syndrome in a large sample of Saudi patients with obstructive sleep apnea

ABSTRACT

To assess the prevalence, clinical characteristics, and predictors of obesity hypoventilation syndrome [OHS] in a large sample of Saudi patients with obstructive sleep apnea [OSA]. This prospective observational study consisted of 1693 patients who were diagnosed to have sleep-disordered breathing using type I attended polysomnography [PSG] between January 2002 and December 2012 in the University Sleep Disorders Center [USDC] at King Saud University Hospital, Riyadh, Kingdom of Saudi Arabia. Out of 1693 OSA patients, OHS was identified in 144 [8.5%] [women 66.7%]. Compared with the pure OSA patients, the OHS patients were significantly older [57.4 +/- 13.4 years versus 46.8 +/- 13.7 years], had a higher body mass index [44.6 +/- 10.8 versus 35.7 +/- 9.2 kg/m[2]], a higher daytime partial pressure of carbon dioxide [PaCO[2]] [56.5 +/- 12.7 versus 41.6 +/-6.7 mmHg], a longer duration of nocturnal oxygen saturation [nSaO[2]] <90% [71.0 +/- 34.3 versus 10.5 +/- 20.5 minutes], and a higher apnea hypopnea index [68.2 +/- 47.1 versus 46.5 +/- 34.1 events/hour]. A multivariate logistic regression analysis showed that serum bicarbonate [odds ratio [OR]=1.17, p=0.0001, confidence interval [CI]=1.10-1.25], and duration of nSaO[2] <90% [OR=1.05, p=0.0001, CI=1.04-1.06] were predictors of OHS. Obesity hypoventilation syndrome is common among Saudi OSA patients referred to the Sleep Disorders Center. Serum bicarbonate and duration of nSaO[2] <90% are independent predictors of OHS among patients with OSA