Pharmacist workload and pharmacy characteristics associated with the dispensing of potentially clinically important drug-drug llnteractions

Background: Drug-drug interactions (DDIs) are preventable medical errors, yet exposure to DDIs continues despite systems that are designed to prevent such exposures. The: purpose of this study was to examine pharmacy characteristics that may be associated with dispensed potential DDIs. Methods: This study combined survey data from community pharmacies in 18 metropolitan statistical areas with pharmacy claims submitted to 4 pharmacy benefit managers (PBMs) over a 3-month period from January 1, 2003 to March 31, 2003. Pharmacy characteristics of interest included prescription volume, the number of full-time equivalent pharmacists and pharmacy staff, computer software programs, and the ability to modify those programs with respect to DDI alerts, the use of technologies to assist in receiving, filling and dispensing medication orders, and prescription volume. The dependent variable in this study was the rate of dispensed medications that may interact. Results: A total of 672 pharmacies were included in the analysis. On average (+/- SD), the respondents filled 1375 +/- 691 prescriptions per week, submitted 17,948 +/- 23,889 pharmacy claims to the participating PBMs, had 1.2 +/- 0.3 full-time equivalent pharmacists per hour open, and 545 (81%) were affiliated with a chain drug store organization. Factors significantly related to an increased risk of dispensing a potential DDI included pharmacist workload (odds ratio [OR] 1.03; 95% confidence interval [CI] 1.028-1.048), pharmacy staffing (OR 1.10; 95% CI: 1.09-1.11), and various technologies (eg, sophisticated telephone systems, internet receipt of orders, and refill requests) that assist with order processing, and the ability to modify DDI alert-screening sensitivity and detailed pharmacological information about DDIs. Conclusions: This study found that there was an increase in the risk of dispensing a potential DDI with higher pharmacist and pharmacy workload, use of specific automation, and dispensing software programs providing alerts and clinical information.