The Association Between Central Nervous System-Active Medication Use and Fall-Related Injury in Community-Dwelling Older Adults with Dementia

Objectives To examine the association between central nervous system (CNS)-active medication use and the risk of fall-related injury in community-dwelling older adults following dementia onset. Further, to evaluate increased risk at higher doses or with a greater number of CNS-active medication classes. Methods Participants included community-dwelling older adults aged 65 years and older with a dementia diagnosis participating in the Adult Changes in Thought Study. From automated pharmacy data, a time-varying composite measure of CNS-active medication use was created. Central nervous system-active medication use was classified as current (use within prior 30 days), recent (prior 31-90 days), past (prior 91-365 days), and nonuse (no exposure in prior year). For current users, standardized daily doses (SDDs) were calculated for each CNS-active medication and summed across medications, and the number of CNS-active medication classes used was also measured. The outcome was fall-related injury based on emergency department, inpatient, and outpatient International Classification of Diseases, Ninth Revision (ICD-9) and external cause of injury (E) codes. Results Among 793 subjects, 303 fall-related injuries occurred over a mean follow-up of 3.7 years (2907 total person-years). Relative to nonuse, fall risk was significantly higher for current use (adjusted hazard ratio [HR] 1.59, 95% confidence internal [CI] 1.19-2.12) but not for past or recent use. Among current users, increased risk was seen across SDD levels: HRs (95% CI): 1.77 (1.19-2.62), 1.79 (1.25-2.56), and 1.35 (0.96-1.92) for less than 1 SDD, 1 to less than 2 SDDs, and 2 or more SDDs, respectively (trend test, p=0.14). A trend was seen for increasing risk with a greater number of CNS-active medication classes; however, this was not statistically significant (trend test, p=0.084). Conclusions Current use of CNS-active medications was associated with fall-related injury in community-dwelling older adults followed from time of dementia onset, with increased risk even with use of low doses.