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 additional pharmacy claims data for all Network Health Plan patients who were cared for by the 38 primary care clinicians (32 physicians, 4 nurse practitioners, and 2 physician assistants) included in our original 6-month study. This follow-up analysis (a) identified all new prescription claims for the 2 groups of clinicians throughout the 12-month follow-up period (June 2002 through May 2003) and (b) assessed all pharmacy claims during the same 12-month period to provide more complete savings estimates and to examine between-group differences in PMPM expenditures.
Results: During 12 months of follow-up, clinicians using the electronic prescribing system continued to have lower prescription costs than the controls. Clinicians using the electronic prescribing system had average costs for 26,674 new prescriptions that were dollar 4.12 lower (95% confidence interval, dollar 1.53-dollar 6.71; P=0.003) and PMPM expenditures that were dollar 0.57 lower than expected based on the changes observed for 24,507 new prescriptions written by clinicians in the control group. The average drug cost savings on new prescriptions were dollar 482 per prescriber per month (PPPM), based upon prescription cost and dollar 465 PPPM based upon PMPM analysis. When all pharmacy claims (156,429) were analyzed, the intervention group.s average prescription cost was dollar 2.57 lower and their PMPM expenditures were dollar 1.07 lower than expected based on the changes observed in the control group. The average drug cost savings on all pharmacy claims were dollar 863 PPPM based on average prescription cost and dollar 873 PPPM based on PMPM analysis. The proportion of prescriptions for highcost drugs that were the target of the CDSS messages to prescribers was a relative 17.5% lower among the intervention group (35.8%) compared with the control group (43.4%; P=0.03).
Conclusions: An electronic prescribing system with integrated decision support shifted prescribing behavior away from high-cost therapies and significantly lowered prescription drug costs. The savings associated with altered prescribing behavior offset the monthly subscription cost of the system.