Benzodiazepine use and hip fractures in the elderly: who is at greatest risk?

BACKGROUND It remains unclear whether benzodiazepine use increases hip fracture incidence. We studied this relationship in a large cohort, controlling for multiple potential confounders. METHODS We analyzed 42 months of New Jersey Medicaid health care claims data for all enrollees. Each eligible person-day was assigned to categories of benzodiazepine exposure and categories of other predictors, based on prior and current medication dispensing and diagnosis information. Hip fractures were identified based on hospital claims with primary discharge diagnosis International Classification of Diseases, Ninth Revision (ICD-9) codes 820.xx. RESULTS Cohort members (n = 125 203) contributed 194 071 person-years and had 2312 eligible hip fractures. After adjustment for age, sex, race, Medicaid nursing home residence, exposure to other psychoactive medications, including antiparkinsonian medications, diagnoses of epilepsy and dementia, and hospitalization in the previous 6 months, the incidence rate of hip fracture was significantly higher compared with no benzodiazepine use for exposure to any benzodiazepine (incidence rate ratio [IRR], 1.24; 95% confidence interval [CI], 1.06-1.44), to a short half-life, high-potency benzodiazepine (IRR, 1.27; 95% CI, 1.01-1.59), during the first 2 weeks after starting a benzodiazepine (IRR, 2.05; 95% CI, 1.28-3.28), during the second 2 weeks after starting a benzodiazepine (IRR, 1.88; 95% CI, 1.15-3.07), and for continued use (IRR, 1.18; 95% CI, 1.03-1.35). CONCLUSIONS The incidence of hip fracture appears to be associated with benzodiazepine use. Contrary to several previous studies, short half-life benzodiazepines are not safer than long half-life benzodiazepines. Hip fracture risk is highest during the first 2 weeks after starting a benzodiazepine and declines thereafter.