A randomized trial of the effectiveness and efficiency of interventions to reduce potential drug interactions in primary care.

The authors tested the effectiveness and estimated the cost of several interventions aimed at reducing drug interactions in primary care by designing a 15-month cluster-controlled trial. The trial involved 265 family physicians and their patients who were randomized into 4 groups: control, report (received feedback reports), session (group sessions), and face-to-face (personal interviews). The outcome was the mean of relevant interactions detected on electronic medical records. Cost-effectiveness was defined as the incremental cost to reduce drug interactions by 1%. The authors detected a baseline mean of 6.7 interactions per 100 patients, which was reduced to 5.3 interactions after follow-up. No improvement was seen in the report group when compared with the control group, whereas progressive improvement in the other groups was noted (P < .001). Incremental cost was higher in the face-to-face group (69.4€ vs 50.7€); cost-effectiveness results were slightly better in the session group (4.2€ vs 4.5€).