Wide variation and patterns of physicians' responses to drug-drug interaction alerts.

Objectives: Providing physicians with alerts about potentially harmful drug-drug interactions (DDIs) is only moderately effective due to high alert override rates. To understand high override behavior on DDI alerts, we investigated how physicians respond to DDIs and their behavior patterns and variations.

Design: Retrospective system log data analysis and records review (sampling 2% of total overrides).

Setting: A large tertiary academic hospital.

Participants: About 560 physicians and their override responses to DDI alerts generated from 1 September to 31 December 2014.

Interventions: Not applicable.

Main Outcome Measure(s): DDI alert frequency and override rate.

Results: We found significant variation in both the number of alerts and override rates at the levels of physicians, departments and drug-class pairs. Physician-level variations were wider for residents than for faculty staff (number of alerts: t = 254.17, P = 0.011; override rates: t = -4.77, P < 0.0001). Using the number of alerts and their override rate, we classified physicians into four groups: inexperienced incautious users, inexperienced cautious users, experienced cautious users and experienced incautious users. Medical department influenced both alert numbers and override rates. Nearly 90% of the overrides involved only five drug-class combinations, which had a wide range of appropriateness in the chart review.

Conclusion: The variations at drug-class levels suggest issues with system design and the DDI rules. Department-level variation may be best addressed at the department level, and the rest of the variation appears related to individual physician responses, suggesting the need for interventions at an individual level.