Age and comorbidities are crucial predictors of mortality in severe obstructive sleep apnoea syndrome.

BACKGROUND

Obstructive sleep apnoea syndrome (OSAS) is a highly prevalent disorder. The prognostic role of comorbidity in patients with OSAS and their role for risk stratification remain poorly defined.

METHODS

We studied 1,592 patients with severe OSAS diagnosed by polysomnography. The primary outcome was all-cause mortality. The standardized mortality ratio (SMR) was estimated as the ratio of observed deaths to expected number of deaths in the general population. The expected numbers of deaths were derived using mortality rates from the general Apulian population. The association of comorbidities with all-cause mortality was assessed using multivariable Cox regression analysis. Finally, recursive-partitioning analysis was applied to identify the combinations of comorbidities that were most influential for mortality and to cluster the patients into risk groups according to individual comorbidities

RESULTS

During 11,721 person-years of follow-up, 390 deaths (3.33 deaths/100 person-years) occurred. The median follow-up was 7 (4-10) years. The SMR was 1.47 (95% confidence intervals 1.33-1.63). Age, sex, obesity, cardiovascular diseases (CVD), moderate-to-severe chronic obstructive pulmonary disease (COPD), chronic kidney disease (CKD) and malignancy were independently associated with mortality risk. Recursive-partitioning analysis allowed distinguishing three clinical phenotypes differentially associated with mortality risk. The combination of CKD with CVDs or with moderate-to-severe COPD conferred the highest risk.

CONCLUSIONS

Severe OSAS is associated with increased risk for all-cause death. Age and comorbidity are crucial predictors of mortality in patients with severe OSAS. Clustering patients according to comorbidities allows identifying clinically meaningful phenotypes.