Background: Hospital pharmacists make many recommendations that improve patients' quality of care and/or reduce drug costs. While the impact of quality-of-care interventions is difficult to quantify, those limited to cost savings could be assessed in a prospective, randomized fashion.

PURPOSE Although newer, heavily promoted medications are commonly prescribed, published evidence and consensus guidelines often support the use of less expensive alternatives. This study was designed to evaluate the impact on prescription costs of a computerized decision support system (CDSS) that provides evidence-based recommendations to clinicians during the electronic prescribing process.METHODS A retrospective cohort study was performed using a pharmacy claims database. Clinicians using the CDSS were matched with a control group by pharmacy billed amount, number of patients treated, and number of new prescriptions fi lled during a 6-month baseline period in which neither group used the system. The primary outcome measure was the difference in prescription costs between the 2 groups after implementation of the CDSS in the intervention group. RESULTSClinicians who received evidence-based messages had signifi cantly lower prescription costs than those in the control group. The average cost per new prescription was $4.16 lower (P = .02) in the intervention group, and the average cost for new and refi lled prescriptions was $4.99 lower (P = .01). The 6-month savings from new prescriptions and their refi lls are estimated to be $3,450 (95% CI, $1,030-$5,863) per clinician.CONCLUSIONS Providing electronic, evidence-based decision support during the prescribing process can shift prescribing decisions toward more evidence-based care and signifi cantly decrease primary care prescription costs.

ome computerized decision support systems (CDSS) have been shown to influence prescribing decisions; however, most published studies have been conducted in hospital settings and examined internally developed CDSS that are not easily exported to other settings. [1][2][3][4][5] Although a few trials have been performed in primary care, these have also typically used custom-built systems, and most have been performed in academically affiliated clinics, have limited their interventions to a single drug class or disease state, and provided relatively short follow-up.6-14 To our knowledge, there are no published studies that have adequately evaluated the long-term impact of commercially available CDSS or electronic prescribing products in a community-based primary care setting.We reported previously the results of a 6-month controlled trial of a commercially available electronic prescribing system with integrated clinical decision support in which new primary care prescription costs were reduced by more than 10% per prescription. 15 Because the original study focused only on new prescriptions (defined as a claim for a medication that the patient had not received in the previous 12 months), we were unable to fully assess the impact of the system on total pharmacy costs. The main objectives of this follow-up report were to determine if the 6-month savings on new prescriptions were sustained during a longer follow-up observation period (12 months) and to evaluate the impact of the CDSS on all p h a rmacy claims (i.e., new prescriptions plus older pre s c r i p t i o n s that were active prior to the intervention) and per-member-permonth (PMPM) expenditures.To help verify that the system was effective at changing prescribing behavior, we also evaluated the utilization of drugs within 8 high-cost therapeutic categories that were targets of the CDSS messaging function. To our knowledge, this is the first controlled study that has formally investigated the impact ABSTRACT OBJECTIVE: We reported previously the results of a 6-month controlled trial in which the use of a commercially available electronic prescribing system with integrated clinical decision support and evidence-based message capability was associated with significantly lower primary care drug costs. The original study focused on new prescriptions, defined as claims for a medication that the patient had not received in the previous 12 months. The main objectives of this follow-up report were to (a) determine if the 6-month savings on new prescriptions were sustained during 12 months of follow-up, (b) evaluate the impact of the computerized decision support system (CDSS) on all pharmacy claims and per-member-per-month (PMPM) expenditures, and (c) evaluate the prescribing behaviors within 8 high-cost therapeutic categories that were frequently targeted by the electronic messages to prescribers to help verify that the drug cost savings were due to the recommendations in the electronic prescribing system. METHODS: Two database queries were performed to identify add...