Long-term follow-up of sleep disordered breathing in older adults

Abstract

Objective: The current study was designed to determine whether, with increasing age, sleep apnea improves, becomes worse, or stays the same.

Background: There is a high prevalence of sleep disordered breathing (SDB) in older adults, but little is known about longitudinal changes. This study followed older adults to examine the natural history of SDB.

Methods: Subjects were randomly selected community-dwelling elderly (n=427). A subset of subjects was studied approximately every 2 years over an 18-year period. Overnight sleep recordings and sleep questionnaires were completed at each time point.

Results: Multiple linear regression showed that three variables were associated with change in respiratory disturbance index (RDI):body mass index (BMI) at initial visit (P=0.001), change in BMI (P=0.02), and a consistent self-report of high blood pressure (P=0.005). RDI increase was associated with BMI increase and presence of self-reported high blood pressure.

Conclusions: The changes in RDI that occurred were associated only with changes in BMI and were independent of age. This underscores the importance of managing weight for older adults, particularly those with hypertension.

Introduction

Epidemiological studies have shown that 15% of men and 5% of women between the ages of 30 and 60 years have sleep disordered breathing (SDB), defined as a respiratory disturbance index of 10 or greater [1]. Using a similar definition of an index of 20 or greater, adults over the age of 65 have considerably higher prevalence rates, reaching 70% for men and 56% for women [2]. Kripke et al. [3] found rates of 10.9% for men and 5.3% for women between the ages of 40 and 60 years using an index of 20 or greater based on oxygen desaturations. Untreated SDB can lead to negative consequences such as heart disease [4], hypertension [5], and shorter survival [6]. Change in weight can also effect the severity of SDB [7], with increased weight being associated with increased severity of SDB. Recent studies have suggested that people with even mild SDB are at greater risk at follow-up for developing hypertension [8], [9].

The amount of apnea frequently varies from night to night [3], so evidently some variation will be observed from year to year [3]. Few studies have followed untreated people with SDB over long time periods. One limitation of the existing literature is that there has been little or no follow-up of untreated patients beyond 5 years. In addition, most studies followed fairly small samples which were selected based on specific criteria such as an initial severity of SDB. These factors may have limited the generalizability of these findings to the older population at large.

Ancoli-Israel and colleagues began studying a large cohort of 427 randomly selected community-dwelling elderly in 1981 [2]. The results from the first visit showed that sleep apnea was extremely common with 24% of the sample meeting a criterion of five or more apneas per hour of sleep, and the majority having greater than ten per hour [2]. The sleep apnea was associated with self-report of nocturnal wandering or confusion, reports of breathing cessation at night, increased daytime sleepiness, greater weight, and more depression. A subset of the sample was followed and re-studied repeatedly. At the first 8.5 year follow-up, there were no significant changes in apnea index (AI) or respiratory disturbance index (RDI) from the initial recording [10]. The current study was designed to determine whether, with increasing age, sleep apnea improved, became worse, or stayed the same.