Effect of Ventilation Therapy on Mortality Rate Among Obesity Hypoventilation Syndrome and Obstructive Sleep Apnoea Patients

Introduction: The prevalence of obesity is continually increasing worldwide, which increases the incidence of obesity hypoventilation syndrome (OHS) and its consequent mortality.

Methods: We reviewed the therapy mode, comorbidity and mortality of all OHS patients treated at our hospital between 2005 and 2016. The control group consisted of randomly selected patients with obstructive sleep apnoea (OSA) treated during the same period.

Results: We studied 206 OHS patients and 236 OSA patients. The OHS patients were older (56.3 versus 52.3 years, p<0.001) and heavier (body mass index 46.1 versus 32.2 kg·m^-2, p<0.001), and the percentage of women was higher (41.2% versus 24.2%, p<0.001), respectively. The OHS patients had more hypertension (83% versus 61%, p<0.001) and diabetes (62% versus 31%, p<0.001) than the OSA patients, but no higher stroke (4% versus 8%, p=0.058) or ischaemic heart disease (14% versus 15%, p=0.437) incidence. The 5- and 10-year, unadjusted survival rates were lower among the OHS patients than among the OSA patients (83% versus 96% and 74% versus 91%, respectively; p<0.001). Differences in mortality rates were not related to age, sex or body mass index; covariates such as Charlson Comorbidity Index and ventilation therapy predicted survival. The mortality rate decreased significantly (p<0.001) both in OHS and OSA patients even after adjusting for covariates.

Conclusions: The mortality rate in OHS was significantly higher than that in OSA patients even after adjusting for covariates. Ventilation therapy by continuous positive airway pressure or noninvasive ventilation have reduced mortality significantly in all patients.