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

Abstract

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.

Keywords: Survival; population; sleep disordered breathing.

Figure 1

Scatterplot showing the strength of the correlation between sleep time spent snoring and the respiratory disturbance index. Spearman correlation (rho 0.5, P < 0.001) for the association between the amount of the night spent snoring and the major index of sleep apnea severity, the respiratory disturbance index, shows that although these are correlated phenomena they do not completely overlap. The second worst snorer, for instance, also had no sleep apnea.

Figure 2

Kaplan-Meier estimation of the probability of mortality of participants with ascending quartiles of sleep time spent snoring. All 4 lines significantly overlap and none are statistically significantly different from any other line, suggesting the amount of time spent snoring has no relationship with mortality risk (see also Table 2 for multivariate confirmation).

Figure 3

Kaplan-Meier estimation of the probability of incident cardiovascular disease in participants with ascending quartiles of sleep time spent snoring. All 4 lines significantly overlap and none are statistically significantly different from any other line, suggesting the amount of time spent snoring has no relationship with cardiovascular disease in general (see also Table 2 for multivariate confirmation).

Figure 4

Kaplan-Meier estimation of the probability of incident stroke in participants with ascending quartiles of sleep time spent snoring. All 4 lines significantly overlap and none are statistically significantly different from any other line, but note that our analyses of stroke may be significantly underpowered (see also Table 2 and the Discussion section).