This study pioneered the use of electronic physician reminders to improve patient safety. Physicians in an outpatient internal medicine clinic received computer-delivered prompts to evaluate a physical finding or symptom, order a test, or change a treatment, based on prespecified protocols; many of these protocols addressed monitoring for adverse effects of medications. For example, if a patient was on a diuretic agent, the physician was prompted to check the serum potassium level. In this crossover study, physicians who received the reminders performed the recommended action significantly more often than physicians who did not receive the prompts, regardless of the physician's level of experience. Subsequent research has confirmed that computerized decision support systems improve physician performance at a variety of processes of care, including patient safety tasks.