Retrospective drug utilization review: impact of pharmacist interventions on physician prescribing

OBJECTIVES To evaluate the impact of retrospective drug utilization review (RDUR), pharmacist's interventions on physician prescribing, and the level of spillover effect on future prescriptions following the intervention. METHODS A retrospective case-control study was conducted at a pharmacy benefits management company using the available prescription data from April 2004 to August 2005. RDUR conflicts evaluated and intervened by a clinical pharmacist served as a case group, whereas conflicts that were not evaluated and intervened by a clinical pharmacist served as a control group. RESULTS A total of 40,284 conflicts in cases and 13,044 in controls were identified. For cases, 32,780 interventions were considered nonrepetitive, and 529 were repetitive. There were 22,870 physicians in cases that received intervention letters and 2348 physicians in the control group that would have received intervention letters during the study period. Each physician received on average 1.4 interventions for cases vs 3.0 for controls. Among the case physicians who were intervened during the study period, 2.2% (505) were involved in a repeated intervention vs 18.2% (428) in controls (P < 0.001), which is an eight-fold difference. The most common conflict intervened on in cases was therapeutic appropriateness (8277, 25.3%), and for controls it was drug-drug interactions (1796, 25.4%). The overall interventional spillover effect in cases was 98.4% vs 89.4% in controls (P = 0.01). CONCLUSION RDUR is an effective interventional program which results in decreased numbers of interventions per physician and provides a significant impact on future prescribing habits.