Effect of a Social Norm Email Feedback Program on the Unnecessary Prescription of Nimodipine in Ambulatory Care of Older Adults: A Randomized Clinical Trial

Abstract

Importance: Nimodipine is a highly prescribed drug for the treatment of cognitive impairment and dementia in Argentina. There is little evidence to support the use of nimodipine for cognitive impairment and dementia. Objective: To test the effectiveness of a behavioral intervention based on social norm feedback to reduce prescription of nimodipine for cognitive impairment in Argentina. Design, Setting, and Participants: This pragmatic parallel-group randomized clinical trial included 2 arms with a 1:1 allocation ratio. General practitioner physicians in the national health care system for older adults in Argentina (INSSJP-PAMI) with history of high nimodipine prescription rate were enrolled. The study was conducted from May 2019 to October 2019, and data were analyzed from November 2019 to February 2020. Interventions: The treatment group received 2 emails with evidence-based information about nimodipine plus the individual's level of nimodipine prescription compared with their peers. The control group received 2 emails with general information about the risks of overprescription in older adults. Main Outcomes and Measures: The primary outcome was the cumulative number of nimodipine prescriptions per 1000 prescriptions of all drugs made by the targeted physicians during the 6 months of the study. Secondary outcomes included annual monetary savings attributable to the intervention and physicians' qualitative perceptions of the acceptability of the procedure. Results: Of 1811 physicians enrolled, 906 physicians (354 [39.1%] women; mean [SD] age, 57.10 [10.73] years) were randomized to treatment and 905 participants (331 [36.6%] women; mean [SD] age, 56.49 [10.47] years) to the control group. Physicians in the treatment group wrote a mean of 93.25 (95% CI, 89.27 to 97.24) prescriptions of nimodipine, compared with 98.99 (95% CI, 95.00 to 102.98) prescriptions among practitioners in the control group during the half-year of the intervention (mean difference, -5.73 [95% CI, -11.38 to -0.10] prescriptions; P =.046), which meant a 5.79% reduction. Regression analysis revealed a significant association of the group condition with number of prescriptions per 1000 total prescriptions when controlling for baseline prescriptions (B = -0.312 [95% CI, -0.465 to -0.160]; P