Risk of hip/femur fractures during the initiation period of α‐adrenoceptor blocker therapy among elderly males: a self‐controlled case series study

Aims This study aimed to evaluate the risk of hip/femur fractures during the initiation period of α‐adrenoceptor blocker therapy using the National Health Insurance claims database, Taiwan, with a self‐controlled case series design. Methods All male beneficiaries aged over 50 years as of 2007, who were incident users of α‐adrenoceptor blockers and also had a diagnosis of hip/femur fracture within the 2007–2009 study period were identified. The first day when the α‐adrenoceptor blocker was prescribed was set as the index date. We partitioned the initial 21 day period following the index date as the post‐exposure risk period 1, days 22–60 after the index date as the post‐exposure risk period 2, the 21 day period prior to the index date as the pre‐exposure risk period 1 and days 22–60 prior to the index date as the pre‐exposure risk period 2. The remainder of the study period was defined as the unexposed period. The incidence rate ratio (IRR) of hip/femur fractures within each risk period compared with the unexposed period was estimated using a conditional Poisson regression model. Results A total of 5875 men were included. Compared with the unexposed period, the IRR of hip/femur fractures was 1.36 (95% confidence interval 1.06, 1.74, P = 0.017) within the post‐exposure risk period 1 for patients without concomitant prescriptions of anti‐hypertensive agents. Conclusions Use of α‐adrenoceptor blockers was associated with a small but significant increase in the risk of hip/femur fractures during the early initiation period in patients without concomitant prescriptions of anti‐hypertensive agents.