Effect of Drug Cost Reduction Before and After Expansion of Pharmacist’s Prospective Audit and Feedback Intervention for Patients Receiving a Specific Antibiotic to All Injectable Antibiotics

Prospective audit and feedback (PAF) by pharmacists is recommended for antimicrobial stewardship. We examined the effectiveness of PAF by pharmacists in reducing drug costs. PAF was provided to selected patients using specific antibiotics (eg, carbapenem, anti-MRSA drug, and tazobactam/piperacillin) in 2016 (before the expansion) and to all the patients using injectable antibiotics in 2017 (after the expansion), for a period of one year for each. The average reduction in the cost of monthly antibiotics and the estimated cost reductions per suggestion by pharmacists were compared before and after the expansion, respectively. We retrospectively compared the estimated drug cost (assuming that antibiotic therapy at the time of the prescription was continued for the actual administration duration) with the drug cost following the prescription suggestion. The estimated reduction in drug cost was calculated by subtracting the actual drug cost from the estimated drug cost. The mean decrease in the cost of specific antibiotics before and after the intervention was not significantly different (at -171,964 yen/month), but there was a significant reduction of 545,286 yen/month for non-specific antibiotics (P < 0.001). There were 190 pharmacist suggestions before and 607 after the expansion. The estimated cost reduction per suggestion by pharmacists was -2,526 yen before the expansion but significantly increased to 4,330 yen after the expansion (P = 0.034). The results suggest that continuous intervention in selected patients using specific antibiotics is unlikely to reduce drug costs, but the expansion of surveillance to include all the patients using injectable antibiotics may reduce drug costs.