Prescription characteristics associated with increased fall-related injury risk among older adults prescribed benzodiazepines: a cohort study

Statement of Purpose

Benzodiazepines (BZDs) are associated with a number of safety concerns among older adults, including fall-related injury (FRI). Despite the known fall risks of BZD and the burden of FRI among older adults, the medications are still widely prescribed. Clinicians would benefit from more information about who, among those prescribed BZD, is at the most elevated risk for FRI. We focused on potentially modifiable characteristics, including of the prescribed BZD as well as other opioid and psychotropic medications.

Methods/Approach

We conducted 2 separate retrospective cohort studies using a 20% random sample of Medicare beneficiaries from July of 2013 to September of 2015 to examine factors associated with fall-related injury (FRI) within 30d of an incident or prevalent BZD prescription claim in Medicare Part D. FRI events were identified using ICD-9 claims, applying an algorithm validated by Min et al. Our exposures of interest focused on the index BZD prescription and other prescription medications. We fit Cox proportional hazards models for each cohort (incident and prevalent) to examine factors associated with a FRI event, adjusted for other clinical and demographic characteristics.

Results

Among incident and prevalent BZD users, 3.84% and 2.92% had a FRI within 30d, respectively. Fewer days of medication prescribed were associated with higher risk of fall-related injury among both incident and prevalent users (e.g., compared to 31+d, <14d adjusted hazard ratio [aHR] 1.57 [95% CI 1.46–1.68] and 1.31 [CI 1.22–1.40], respectively). In addition, among prevalent users, those with the lowest medication possession ratio (<50% of days during the baseline 6 months with BZD exposure [i.e., MPR <0.5]) had an elevated risk of injury (relative to MPR 0.5–1, aHR 1.09 [CI 1.04–1.14]). Current antiepileptic and opioids use were both associated with increased risk of FRI among both incident (1.07 [95% CI 1.02–1.12] and 1.42 [CI 1.36–1.48], respectively) and prevalent BZD users (1.14 [CI 1.10–1.18] and 1.28 [CI 1.22–1.33]).

Conclusions

Prescribing fewer days of BZD is not associated with lower risk of OD events for either incident (i.e., new) or prevalent (i.e., ongoing) patients prescribed BZD. In addition, those prevalent users with the lowest rate of baseline use were at elevated risk of FRI. Finally, among those prescribed BZD, use of antiepileptics and of opioids both increase the risk of fall-related injury.

Significance

These findings run counter to conventional wisdom that a more limited exposure to BZD is safer than more regular, consistent use. In addition, they extend the concerns about risks associated with BZD co-prescribing beyond opioids.