Physicians' decisions to override computerized drug alerts in primary care

Background: Although computerized physician order entry reduces medication errors among inpatients, little is known about the use of this system in primary care. Methods: We calculated the override rate among 3481 consecutive alerts generated at 5 adult primary care practices that use a common computerized physician order entry system for prescription writing. For detailed review, we selected a random sample of 67 alerts in which physicians did not prescribe an alerted medication and 122 alerts that resulted in a written prescription. We identified factors associated with the physicians' decisions to override a medication alert, and determined whether an adverse drug event (ADE) occurred. Results: Physicians overrode 91.2% of drug allergy and 89.4% of high-severity drug interaction alerts. In the multivariable analysis using the medical chart review sample (n=189), physicians were less likely to prescribe an alerted medication if the prescriber was a house officer (odds ratio [OR], 0.26; 95% confidence interval [CI], 0.08-0.84) and if the patient had many drug allergies (OR, 0.70; 95% CI, 0.53-0.93). They were more likely to override alerts for renewals compared with new prescriptions (OR, 17.74; 95% CI, 5.60-56.18). We found no ADEs in cases where physicians observed the alert and 3 ADEs among patients with alert overrides, a nonsignificant difference (P=.55). Physician reviewers judged that 36.5% of the alerts were inappropriate. Conclusions: Few physicians changed their prescription in response to a drug allergy or interaction alert, and there were few ADEs, suggesting that the threshold for alerting was set too low. Computerized physician order entry systems should suppress alerts for renewals of medication combinations that patients currently tolerate.