The Association Between Central Nervous System (CNS)-Active Medication Use and Fall-Related Injury in Older Adults with Dementia

Abstract

Introduction: Few studies have examined the association between central nervous system (CNS)-active medications and fall-related injury in older adults with dementia, a high-risk population. Prior studies have been limited to institutional settings. We evaluated the association between CNS-active medication use and fall-related injury in community-dwelling older adults with dementia. Methods: The population was community-dwelling older adults aged ≥65 years with a research dementia diagnosis participating in the Adult Changes in Thought Study. From automated pharmacy data, we created a time-varying composite measure of CNS-active medication use, including benzodiazepines/sedatives, anticholinergics, antidepressants, antipsychotics, opioids, and skeletal muscle relaxants. CNS use was classified as: current (≤30 days before fall-related injury), recent (31-90 days before), past (91-365 days before), and non-use. The outcome was fall-related injury based on inpatient and outpatient diagnosis (ICD-9) and injury (E) codes. We calculated standardized daily doses (SDDs) for each CNS-active medication and summed the SDDs across medications. We estimated hazard ratios (HR) with 95% confidence intervals (CI) from Cox models using time since dementia onset as the time axis and adjusting for health and functional characteristics. Results: Among 793 subjects with dementia, there were 303 fall-related injuries over a mean follow-up of 3.7 years (2,907 total person-years). Relative to non-use, the fall risk (hazard) was significantly higher for current use (HR 1.59; 95% CI 1.19-2.12), but not for past use (HR 0.84; 95% CI 0.55-1.29) or recent use (HR 0.94; 95% CI 0.59-1.69). When estimating a time-varying HR, the contrast in fall hazards between current and no use of CNS-active medications appeared greatest soon after dementia onset. We did not observe significant differences by dose. Conclusion: Current use of CNS-active medications, but not total dose, was associated with fall-related injuries in community-dwelling older adults with dementia, which appeared greatest soon after dementia diagnosis. Time-varying differences in risk between current users and non-users could be explained by a variety of factors such as more careful prescribing as dementia progresses. Additional examination is needed to further our understanding of these phenomena.