The association of sleep-disordered breathing with objectively-assessed risk of falls

Abstract

Introduction Sleep-disordered breathing (SDB) is associated with decrements in cognitive function. Recent data show that impairments in cognition impact the risk of falls. We sought to determine if the presence of SDB affects the risk of falling as assessed by gait tasks in Wisconsin Sleep Cohort Study participants. Materials and methods Adult subjects (n = 476), selected from an employed-population sample of adults in 1988, were polysomnographically-assessed for SDB-characterized by the apnea–hypopnea index (AHI, events/h) – and also had gait evaluations. Gait was assessed with: (1) the Timed Up & Go task, and; 2) the Timed Up & Go task while counting backwards by 3’s (Timed Up & Go-CB). To test whether SDB was associated with prolonged times of gait tasks indicating an increased risk of falling, linear models regressed gait task times on AHI with adjustments for age, gender, and body mass index (BMI). Results 476 subjects had an opportunity to complete the Balance and Gait Tasks; 2 subjects who were physically unable to complete the tasks and 16 subjects who used an assistive device during the tasks were excluded from the analysis. The 458 remaining subjects (46% female) were an average 65 (range: 45–82) years old at the time of testing. Both Timed Up & Go (mean 11 ± 2 s) and Timed Up & Go-CB (mean 13 ± 6 s) demonstrated prolongations of times to completion with age, BMI and AHI. After adjusting for the number of correct subtractions and errors committed, age, gender and BMI, there was a statistically significant relationship between increasing AHI and increased Timed Up & Go-CB time to completion; for every 10 point increase in AHI there was a 2.2 s increase in completion time (p < 0.001). In addition, the difference in seconds between the time to complete Timed Up & Go-CB and Timed Up & Go (mean 1.9 ± 5.0 s) was significantly associated with the increased AHI (1.9 s increase per 10 event/h increase in AHI) after multivariable adjustments (p < 0.001); i.e., the additional cognitive burden of counting backwards while performing the gait task was associated with significantly greater reductions in Timed Up & Go performance in subjects with more severe SDB. Conclusion More severe SDB is associated with decrements in gait tasks performance, particularly the dual-task Timed Up and Go Counting Backwards. SDB-related lower cognitive reserve may lead to worse gait performance and, therefore, possibly a higher risk for injurious falls. Acknowledgements Funding support from NIH grants R01HL62252, 1R01AG036838–01A1, and 1UL1RR025011.