Abstract
RATIONALE: Whether sleep-disordered breathing (SDB) severity and diminished lung function act synergistically to heighten the risk of adverse health outcomes remains a topic of significant debate. OBJECTIVES: The current study sought to determine whether the association between lower lung function and mortality would be stronger in those with increasing severity of SDB in a community-based cohort of middle-aged and older adults. METHODS: Full montage home sleep testing and spirometry data were analyzed on 6,173 participants of the Sleep Heart Health Study. Proportional hazards models were used to calculate risk for all-cause mortality, with FEV(1) and apnea-hypopnea index (AHI) as the primary exposure indicators along with several potential confounders. MEASUREMENTS AND MAIN RESULTS: All-cause mortality rate was 26.9 per 1,000 person-years in those with SDB (AHI ≥5 events/h) and 18.2 per 1,000 person-years in those without (AHI <5 events/h). For every 200-ml decrease in FEV(1), all-cause mortality increased by 11.0% in those without SDB (hazard ratio, 1.11; 95% confidence interval, 1.08-1.13). In contrast, for every 200-ml decrease in FEV(1), all-cause mortality increased by only 6.0% in participants with SDB (hazard ratio, 1.06; 95% confidence interval, 1.04-1.09). Additionally, the incremental influence of lung function on all-cause mortality was less with increasing severity of SDB (P value for interaction between AHI and FEV(1), 0.004). CONCLUSIONS: Lung function was associated with risk for all-cause mortality. The incremental contribution of lung function to mortality diminishes with increasing severity of SDB.