Electronic notifications about drug substitutes can change physician prescription habits: a cross-sectional observational study.

Background: A health maintenance organization (HMO) provides physicians with electronic notifications regarding HMO-recommended drug substitutes.

Objective: Investigating factors affecting physicians' compliance and evaluating associated cost savings.

Design: A cross-sectional observational study of all physicians in the HMO's clinics from June 2005 to February 2006.

Setting: Recording physician ID, initial drug choice, final drug choice, elapsed time between initial and final choices, and pharmacological details.

Participants: Out of 2120 physicians, 647 physicians met the inclusion criteria. They prescribed 1.21 million prescriptions.

Intervention: Transparently recording physicians' response to HMO-recommended drug substitutes within a drug-prescription sub-system of an electronic medical record.

Measurements: Compliance pattern, factors affecting compliance, and cost savings associated with compliance.

Results: Thirty percent of prescriptions did not comply with substitute recommendations. Compliance was most strongly affected by the substitute type, whether generic or therapeutic. Physician workload and age were found second and third in effect magnitude. Compliance was found to be non-automatic, selective and deliberate, suggesting that maintaining quality of care guides physicians in the prescription process. At least 4% of costs for prescribed drugs were saved as a result of compliance with substitute recommendations.

Conclusions: Physicians selectively complied with electronic recommendations to substitute less costly for more costly drugs. Compliance was neither automatic nor thoughtless and entailed cost containment with possibly marginal compromise on quality of care or none at all, as compliance mostly involved substituting generic for patent drugs. We strongly feel that the results can be generalized to other HMOs as well.