Mean nocturnal respiratory rate predicts cardiovascular and all-cause mortality in community-dwelling older men and women

Abstract

Respiratory frequency (f _R) predicts in-hospital and short-term mortality in patients with a variety of pathophysiological conditions, but its predictive value for long-term cardiovascular and all-cause mortality in the general population is unknown. Here, we investigated the relationship between mean nocturnal f _R and mortality in community-dwelling older men and women.We measured mean nocturnal f _R during sleep from overnight polysomnography in 2686 men participating in the Osteoporotic Fractures in Men Study (MrOS) Sleep study and 406 women participating in the Study of Osteoporotic Fractures (SOF) to investigate the relationship between mean nocturnal f _R and long-term cardiovascular and all-cause mortality.166 (6.1%) men in the MrOS cohort (8.9±2.6 years' follow-up) and 46 (11.2%) women in the SOF cohort (6.4±1.6 years' follow-up) died from cardiovascular disease. All-cause mortality was 51.2% and 26.1% during 13.7±3.7 and 6.4±1.6 years' follow-up in the MrOS Sleep study and the SOF cohorts, respectively. Multivariable Cox regression analysis adjusted for significant covariates demonstrated that f _R dichotomised at 16 breaths·min^-1 was independently associated with cardiovascular mortality (MrOS: hazard ratio (HR) 1.57, 95% CI 1.14-2.15; p=0.005; SOF: HR 2.58, 95% CI 1.41-4.76; p=0.002) and all-cause mortality (MrOS: HR 1.18, 95% CI 1.04-1.32; p=0.007; SOF: HR 1.50, 95% CI 1.02-2.20; p=0.04).In community-dwelling older men and women, polysomnography-derived mean nocturnal f _R ≥16 breaths·min^-1 is an independent predictor of long-term cardiovascular and all-cause mortality. Whether nocturnal mean f _R can be used as a risk marker warrants further prospective studies.

Figure 1.

Flow charts of participants included in the analysis of respiratory rate for the MrOS cohort (top) and SOF (bottom).

Figure 2.

Mortality analysis of nocturnal respiratory rate. Kaplan-Meier curves for quartiles of respiratory rate in the MrOS sleep cohort (A) and the SOF cohort (B) and log-rank test results. Panels C (MrOS cohort) and D (SOF cohort) show mortality for respiratory rates dichotomized at 16 breaths per minute.