Reasons provided by prescribers when overriding drug-drug interaction alerts.

Objectives: To investigate prescribers' rationales for overriding drug-drug interaction (DDI) alerts and to determine whether these reasons were helpful to pharmacists as a part of prescription order verification.

Study Design: An observational retrospective database analysis was conducted using override reasons derived from a computerized system at 6 Veterans Affairs medical centers.

Methods: Data on DDI alerts (for interactions designated as "critical" and "significant") were obtained from ambulatory care pharmacy records from July 1, 2003, to June 30, 2004. Prescribers' reasons for overriding alerts were organized into 14 categories and were then rated as clinically useful or not to the pharmacist in the assessment of potential patient harm.

Results: Of 291,890 overrides identified, 72% were for critical DDIs. Across the Veterans Affairs medical centers, only 20% of the override reasons for critical DDI alerts were rated as clinically useful for order verification. Despite a mandatory override reason for critical DDI alerts, 53% of the responses were "no reason provided." The top response categories for critical and significant DDI alerts were "no reason provided," "patient has been taking combination," and "patient being monitored."

Conclusions: When given the opportunity to provide a reason for overriding a DDI alert, prescribers rarely enter clinical justifications that are useful to order verification pharmacists. This brings into question how computerized physician order entry systems should be designed.