Evaluation of an Electronic Critical Drug Interaction Program Coupled with Active Pharmacist Intervention

Background: Failure to detect significant drug interactions may result in adverse outcomes. While proper screening and management of drug interactions can prevent the majority of adverse events, studies indicate that current practice is suboptimal. In the last quarter of 2001, physicians and pharmacists in Kaiser Permanente Colorado, a group model health maintenance organization, developed an electronic critical drug interaction alert program (CDIX). Electronic screening was coupled with active intervention to prevent dispensing of critically interacting drug combinations. Objective: To assess the impact of CDIX on the co-dispensing ol critically interacting drug combinations. Methods: A physician and team of outpatient pharmacists and clinical pharmacy staff developed a condensed list of critical drug interactions (8 drug combinations) to be included in the evaluation of CDIX. Monthly electronic outpatient pharmacy data were collected 20 months before and 37 months after CDIX implementation, with no lag period following implementation. Univariate analyses were completed to compare baseline subject characteristics of the pre- and post-CDIX groups using χ2 and Wilcoxon Rank Sum tests. Interrupted time series analysis was used to estimate changes in the rates of critical drug interactions. Results: Three hundred sixty-seven instances of co-dispensing were observed in 348 subjects during the pre-CDIX period and 256 instances of co-dispensing were observed in 248 subjects during the post-CDIX period. Following CDIX implementation, the overall rate of co-dispensing dropped abruptly from 21.3 to 14.7 per 10,000 prescriptions, representing a relative decrease in co-dispensing of 31% from the month before CDIX implementation (p = 0.0125). Significant reductions in co-dispensing were noted for 7 of the 8 drug class combinations. Conclusions: Employing an intervention system that limits electronic alerts regarding drug interactions to those deemed critical but that also requires pharmacist intervention and collaboration with the prescriber decreases the number of critical drug interactions dispensed.