Sleep apnea and 20-year follow-up for all-cause mortality, stroke, and cancer incidence and mortality in the Busselton Health Study cohort.

OBJECTIVE: To ascertain whether objectively measured obstructive sleep apnea (OSA) independently increases the risk of all cause death, cardiovascular disease (CVD), coronary heart disease (CHD), stroke or cancer. DESIGN: Community-based cohort. SETTING AND PARTICIPANTS: 400 residents of the Western Australian town of Busselton. MEASURES: OSA severity was quantified via the respiratory disturbance index (RDI) as measured by a single night recording in November-December 1990 using the MESAM IV device, along with a range of other risk factors. Follow-up for deaths and hospitalizations was ascertained via record linkage to the end of 2010. RESULTS: We had follow-up data in 397 people and then removed those with a previous stroke (n = 4) from the mortality/ CVD/CHD/stroke analyses and those with cancer history from the cancer analyses (n = 7). There were 77 deaths, 103 cardiovascular events (31 strokes, 59 CHD) and 125 incident cases of cancer (39 cancer fatalities) during 20 years follow-up. In fully adjusted models, moderate-severe OSA was significantly associated with all-cause mortality (HR = 4.2; 95% CI 1.9, 9.2), cancer mortality (3.4; 1.1, 10.2), incident cancer (2.5; 1.2, 5.0), and stroke (3.7; 1.2, 11.8), but not significantly with CVD (1.9; 0.75, 4.6) or CHD incidence (1.1; 0.24, 4.6). Mild sleep apnea was associated with a halving in mortality (0.5; 0.27, 0.99), but no other outcome, after control for leading risk factors. CONCLUSIONS: Moderate-to-severe sleep apnea is independently associated with a large increased risk of all-cause mortality, incident stroke, and cancer incidence and mortality in this community-based sample.

Snoring is not associated with all-cause mortality, incident cardiovascular disease, or stroke in the Busselton Health Study.

STUDY OBJECTIVES: To ascertain whether objectively measured snoring increases mortality, cardiovascular disease, or stroke risk over the effects of obstructive sleep apnea and other established risk factors. DESIGN: Community-based cohort. PARTICIPANTS: 400 residents of the Western Australian town of Busselton. INTERVENTIONS: N/A. MEASUREMENTS: Snoring and obstructive sleep apnea were quantified via the percentage of the night spent snoring and the respiratory disturbance index as measured by a single night recording in November-December 1990 by a home sleep apnea monitoring device (MESAM IV), along with a range of cardiovascular disease risk factors. Follow-up for deaths and cardiovascular hospitalizations was ascertained via record linkage until the end of 2007. RESULTS: Our analytical sample of 380 people was made up of the 397 people for whom the authors had follow-up data, minus 17 people who reported a previous stroke or heart attack at baseline (n = 380/400 = 95% of cohort). Snoring was observed for a mean/median of 32.0/27.4% of the night (standard deviation = 23.9%; range = 0-97.2%). There were 46 deaths, 68 cardiovascular events, and 24 strokes during 17 yr of follow-up. Snoring as either a categoric or continuous variable was not significantly associated with death, incident cardiovascular disease, or stroke in both unadjusted Cox regression models and in models that adjusted for obstructive sleep apnea and other risk factors. CONCLUSIONS: No measure of snoring was associated with all-cause mortality, or incident cardiovascular disease or stroke over 17 yr in this community-based sample.

Sleep apnea as an independent risk factor for all-cause mortality: the Busselton Health Study.

BACKGROUND: Previously published cohort studies in clinical populations have suggested that obstructive sleep apnea (OSA) is a risk factor for mortality associated with cardiovascular disease. However, it is unknown whether sleep apnea is an independent risk factor for all-cause mortality in a community-based sample free from clinical referral bias. METHODS: Residents of the Western Australian town of Busselton underwent investigation with a home sleep apnea monitoring device (MESAM IV). OSA was quantified via the respiratory disturbance index (RDI). Mortality status was determined in 397/400 participants (99.3%) after up to 14 years (mean follow-up 13.4 years) by data matching with the Australian National Death Index and the Western Australian Death Register. Univariate analyses and multivariate Cox proportional hazards modelling were used to ascertain the association between sleep apnea and mortality after adjustment for age, gender, body mass index, mean arterial pressure, total cholesterol, high-density lipoprotein cholesterol, diabetes, and medically diagnosed angina in those free from heart attack or stroke at baseline (n = 380). RESULTS: Among the 380 participants, 18 had moderate-severe OSA (RDI > or = 15/hr, 6 deaths) and 77 had mild OSA(RDI 5 to < 15/hr, 5 deaths). Moderate-to-severe OSA was independently associated with greater risk of all-cause mortality (fully adjusted hazard ratio [HR] = 6.24, 95% CL 2.01, 19.39) than non-OSA (n = 285, 22 deaths). Mild OSA (RDI 5 to < 15/hr) was not an independent risk factor for higher mortality (HR = 0.47, 95% CL 0.17, 1.29). CONCLUSIONS: Moderate-to-severe sleep apnea is independently associated with a large increased risk of all-cause mortality in this community-based sample.