Comorbidities and survival in obstructive sleep apnoea beyond the age of 50

Background Although mortality risk associated with obstructive sleep apnoea (OSA) tends to disappear from the age of 50, it has been suggested that OSA treatment by continuous positive airway pressure (CPAP) improves survival even in older subjects. Life expectancy of subjects with several diseases is worse if OSA coexists. The objectives of this study were to evaluate the relevance of comorbidities in the relationship between OSA and mortality, and in the effect of CPAP on survival, in subjects >= 50 years old. Methods Data from 810 patients studied by polysomnography for suspected OSA between 1991 and 2000 were retrospectively evaluated. In 2009, state of survival and use of CPAP were enquired. Three hundred and thirteen subjects were < 50 and 497 were >= 50 years at diagnosis. Results Age and comorbidities, but not apnoea /hypopnoea index (AHI) or lowest nocturnal arterial oxygen saturation (Nadir SaO(2)), predicted mortality in the whole sample. Nadir SaO(2) was related to mortality among the younger subjects without comorbidities (P = 0.01), but not among the older subjects. In the older patients with an AHI > 30 CPAP treatment was associated with a better survival only if comorbidities coexisted. Conclusions Unlike in younger subjects, in subjects >= 50 years old, comorbidities do not mask an effect of OSA on mortality. Among OSA subjects >= 50 years old, comorbidities could separate those who may expect an improvement in survival with CPAP treatment from those who may not. Possibly, after the age of 50, OSA per se does not affect survival, but worsens prognosis of subjects with coexisting diseases.