Outpatient Benzodiazepine Prescribing, Adverse Events, and Costs

Objectives: The objectives of this preliminary study were to identify a cohort of patients receiving outpatient prescriptions for a class of medications, benzodiazepines, that are known to increase the risk of adverse events, and to analyze the temporal association between outpatient benzodiazepine usage and inpatient and outpatient injury-related health care encounters for this cohort. Methods: As part of a larger research program on high-risk medications and patient injuries, we identified 17,558 patients receiving benzodiazepine outpatient prescriptions at one Veterans Health Administration (VHA) hospital system, with 9,304 individuals more than 59 years old. Adverse outcomes of interest, viz., inpatient or outpatient health care encounters coded as injuries while using benzodiazepines, were analyzed. Direct medical costs for inpatient stays and average costs for outpatient visits were obtained from cost extracts from the VHA Decision Support System. Modified Beers criteria (Zhan et al., JAMA 2001;286(22):2823-9) for potentially inappropriate medications in the elderly, irrespective of dose, were applied to three years of outpatient prescription data for the cohort of patients more than 59 years old. More than 1 million outpatient prescriptions were analyzed by Zhan's modified Beers inappropriateness categories, namely, always avoid, rarely appropriate, and some indications. Results: For the 17,558 patients receiving outpatient benzodiazepines, we identified 297 inpatient injury admissions and 2,977 outpatient injury encounters for 1,352 patients that occurred while using benzodiazepines at the time of the injury. Over $3 million dollars in direct medical costs were associated with these injuries. Conclusions: Pharmacy Benefit Management data linked with clinical administrative data can be used to identify evidence of adverse events (patient injuries) linked to potentially inappropriate prescribing patterns in elderly outpatients.