Impact of physician reminders on the use of influenza vaccinations: a randomized trial.

OBJECTIVE To analyze the impact of mailed physician reminders to immunize their patients. DESIGN Randomized trial involving Washington State physiatrists participating in the Medicare program. In 1997, all physiatrists in the state were separated into solo or group practice. Solo physicians and group practices were then separately randomized to receive 4 monthly reminders to have their patients immunized. In 1998, the intervention and control groups were switched. SETTING The state of Washington. PATIENTS A total of 4300 Medicare outpatients seen in Washington State in 1997 and 4025 patients in 1998. INTERVENTION Repeated mailer. MAIN OUTCOME MEASURE By using multivariate analysis, Medicare billing data was analyzed to determine the impact of the physician reminders on influenza vaccination rates. RESULTS Among solo practitioners, patients whose physiatrist received the reminder letters in 1998 were 34% more likely (adjusted relative risk [RR] = 1.34; 95% confidence interval [CI],.96-1.88) to have a vaccination billing. Among group practitioners, those patients whose physiatrist received the reminder letters in 1997 were 26% more likely (RR = 1.26; 95% CI,.98-1.60) to have a vaccination billing. These differences, however, were not statistically significant. The adjusted RRs for the remaining intervention groups, solo practitioners in 1997 (RR =.89; 95% CI,.63-1.26), and group practitioners in 1998 (RR = 1.00; 95% CI,.73-1.36), revealed no increase in vaccination billings for patients whose physiatrist received the intervention. CONCLUSIONS Repeated physician reminders did not increase the vaccination rate of Washington State Medicare patients who were seen by physiatrists in 1997 and 1998. These results were consistent whether the physiatrists were in solo or group practice. Other methods should be considered to improve the primary care delivered to this Medicare population.