Health Services Research & Development

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2006 HSR&D National Meeting Abstract


3053 — Concomitant Use of Benzodiazepines and Other Drugs and Risk of Injury in Community-Dwelling Veterans

Author List:
Spehar AM (VISN-8 Patient Safety Center; USF College of Public Health; Suncoast Ctr. For Patient Safety at USF)
French DD (VISN 8 Measurement & Evaluation Team)
Campbell RR (VISN 8 Patient Safety Center)
Means H (VISN 8 Pharmacy Benefit Management)
Chirikos TN (H. Lee Moffitt Cancer Center & Research Institute & USF, Tampa, FL)
Bulat T (VISN 8 Patient Safety Cener; JAH Falls Clinic; USF College of Medicine)

Objectives:
1) To use VHA outpatient pharmacy datasets linked with healthcare outcomes datasets to examine the occurrence of concomitant use of benzodiazepines and other drugs. 2) To quantify the effect of these drug combinations on the likelihood of an injury-related healthcare episode in community-dwelling veterans.

Methods:
We linked outpatient prescription data and inpatient/outpatient medical utilization records for 13,745 patients receiving outpatient benzodiazepine and over 1.5 million non-benzodiazepine prescriptions in a VA hospital system over three years. Injuries and adverse events were identified using ICD-9-CM coding for injuries and poisoning (800-999), and associated into injury episodes of care. Micromedex software was used to identify “major” severity combinations of benzodiazepines and other drugs. We restricted our analysis to those drug combinations within a 30-day period prior to an injury-related healthcare event. We used a multivariate model to adjust this risk of injury-related healthcare episode for impact of comorbidities, hospital discharges, marital status, age, mean arterial pressure, and body mass index, as well as dose of benzodiazepines, converted to Valium equivalents, and benzodiazepine duration.

Results:
Of the 1110 unique individuals with an injury, 790 (71%) had used benzodiazepines in combination with another drug, and this increased the odds of an injury more than twofold. Dose and duration of benzodiazepines, as well as certain comorbidities, were also associated with increased risk for injury, whereas being married reduced the risk.

Implications:
Benzodiazepines are medications that are generally acknowledged to independently increase injury risk. Benzodiazepines used concomitantly with other high risk medications can further increase this risk. This study quantified the increased risk of healthcare treatment for an injury that occurred while taking benzodiazepines and other medications and adjusted for other risk factors.

Impacts:
This large-scale study quantified the impact of concomitant use of benzodiazepines and other drugs on the risk of injury in veterans. Researchers must go beyond discussions of potentially inappropriate medications to include analyses linking use with injury healthcare utilization. Better patient and provider education is needed when prescribing potentially high risk medications. Future injury risk models must incorporate complex aspects of medication usage, such as dose and duration, as well as concomitant use, linked to adverse outcomes.