Optimizing number and timing of appointment reminders: a randomized trial

To compare missed appointment rates for patients receiving a single reminder either 3 days prior to a primary care visit, 1 day prior to the visit, or both 3 days and 1 day prior to the visit. Three-armed randomized controlled trial. Text messages or interactive voice response calls were sent to patients with appointments at 25 primary care clinics in an integrated delivery system. A multivariable prediction model was developed to identify patients at high risk of missing appointments, based on prior appointment-keeping history and other variables from electronic health records. Among 54,066 randomized patients, those who received reminders both 3 days and 1 day prior to the visit were less likely to miss their appointment than those who received only a 3-day or 1-day reminder (4.4% vs 5.8% vs 5.3%, respectively; P