title: Rest-activity patterns and falls and fractures in older men.
abstract: Dysregulated rest-activity rhythm (RAR) patterns have been associated with several health conditions in older adults. This study showed that later acrophase was associated with a modestly greater risk of falls but not fractures in elderly men. Associations between dysregulated RAR patterns and osteoporosis risk warrant further investigation.
  
  
  
  The purpose of this study was to investigate the relationship between rest-activity rhythm (RAR) patterns and risk of falls/fractures in older men. We hypothesized that dysregulated RAR would be associated with incident falls/fractures.
  
  
  
  We used wrist-worn actigraphy to measure RAR over 4.8 ± 0.8 24-h periods in men (≥67 years) enrolled in the multicenter Outcomes of Sleep Disorders in Men (MrOS Sleep) Study (n = 3001). Men were contacted every 4 months to report occurrence of falls/fractures. RAR parameters included amplitude (difference between peak and nadir activity in counts/minute), mesor (activity counts/minute), acrophase (time of day of peak activity), and pseudo-F statistic (rhythm robustness) and were evaluated as continuous variables with associations reported per SD increase/decrease in models adjusted for confounders. Logistic regression was used to estimate the likelihood (odds ratio, OR) of recurrent falls in the year after the visit. Proportional hazards models were used to estimate the risk (hazard ratio, HR) of fractures.
  
  
  
  One year after the visit, 417 men (14%) had recurrent (≥2) falls. Later acrophase (OR 1.18, 95% CI 1.06-1.32) was associated with a modestly greater likelihood of falls. In 8.6 years (SD 2.6 years) of >97% complete follow-up, 256 men (8.53%) had a major osteoporotic fracture, 85 (2.8%) had a clinical spine fracture, and 110 (3.7%) had a hip fracture. No consistent, significant associations were observed between RAR patterns and fractures.
  
  
  
  Later acrophase was associated with a modestly greater risk of falls; this association did not translate into a higher fracture risk in this cohort of elderly men.
authors.affiliation: Center for Musculoskeletal Health and Department of Internal Medicine, University of California, Davis Medical Center, 4625 2nd Avenue, Suite 2000, Sacramento, CA, 95817, USA. tsrogers@ucdavis.edu.
authors.forename: Tara S
authors.initials: TS
authors.lastname: Rogers
authors.affiliation: California Pacific Medical Center Research Institute, San Francisco, CA, USA.
authors.forename: Terri L
authors.initials: TL
authors.lastname: Blackwell
authors.affiliation: Center for Musculoskeletal Health and Department of Internal Medicine, University of California, Davis Medical Center, 4625 2nd Avenue, Suite 2000, Sacramento, CA, 95817, USA.
authors.forename: Nancy E
authors.initials: NE
authors.lastname: Lane
authors.affiliation: California Pacific Medical Center Research Institute, San Francisco, CA, USA.
authors.forename: Greg
authors.initials: G
authors.lastname: Tranah
authors.affiliation: Bone and Mineral Unit, Oregon Health & Science University, Portland, OR, USA.
authors.forename: Eric S
authors.initials: ES
authors.lastname: Orwoll
authors.affiliation: Department of Epidemiology, Graduate School of Public Health, University of Pittsburgh, Pittsburgh, PA, USA.
authors.forename: Jane A
authors.initials: JA
authors.lastname: Cauley
authors.affiliation: Departments of Psychiatry and Medicine, University of California, San Diego, La Jolla, CA, USA.
authors.forename: Sonia
authors.initials: S
authors.lastname: Ancoli-Israel
authors.affiliation: California Pacific Medical Center Research Institute, San Francisco, CA, USA.
authors.forename: Katie L
authors.initials: KL
authors.lastname: Stone
authors.affiliation: California Pacific Medical Center Research Institute, San Francisco, CA, USA.
authors.forename: Steven R
authors.initials: SR
authors.lastname: Cummings
authors.affiliation: California Pacific Medical Center Research Institute, San Francisco, CA, USA.
authors.forename: Peggy M
authors.initials: PM
authors.lastname: Cawthon
mesh_terms: D000058:Accidental Falls; D056044:Actigraphy; D000368:Aged; D000369:Aged, 80 and over; D000375:Aging / Q000502:physiology; D015519:Bone Density / Q000502:physiology; D057906:Circadian Clocks / Q000502:physiology; D015444:Exercise / Q000502:physiology*; D005272:Femur Neck / Q000503:physiopathology; D005500:Follow-Up Studies; D006801:Humans; D008297:Male; D058866:Osteoporotic Fractures / Q000503:physiopathology*; D011446:Prospective Studies; D012008:Recurrence; D012146:Rest / Q000502:physiology*; D012307:Risk Factors
keywords: Aging; Epidemiology; Falls; Fractures; Rest-activity rhythm