Factors that influence patient response to requests to change to a unified restrictive formulary.

OBJECTIVE: To determine factors that influence patient willingness to accept a medication change to a unified, restrictive formulary.
DESIGN: Prospective cohort study.
SETTING: University-affiliated hospital-based primary care internal medicine practice. PATIENTS/PARTICIPANTS: Two hundred ninety-seven members of a managed care plan who had received a prescription for a nonformulary medication in the previous 4 months and whose primary care physician approved a conversion to a formulary medication.
INTERVENTIONS: Clinical nurses invited patients to change to a formulary medication at the time of a telephone refill request based on a standard script.
MEASUREMENTS AND MAIN RESULTS: The overall conversion rate to the formulary medication was 59.8%. Seventy-four percent of patients who requested a refill by telephone converted to the formulary (odds ratio [OR], 2.24; 95% confidence interval [CI], 1.02 to 4.72). Patient age (OR, 1.03; CI, 1.01 to 1.05) and male gender (OR, 2.00; CI, 1.09 to 3.67) were each significant correlates of conversion. After adjustment in a multivariable model, only telephone refill request (adjusted OR, 2.31; CI, 1.07 to 4.97) and age (adjusted OR, 1.03; CI, 1.01 to 1.06) remained significant. Among the patients who made a telephone refill request, those who converted were more likely to completely trust their physician's judgment (P=.04) and to trust their physician to put their health over cost concerns (P=.05). Formulary conversion reduced costs beginning 3 months after the conversion date.
CONCLUSIONS: A protocol for encouraging conversion to a unified formulary at the point of a telephone refill request increases formulary compliance rates and reduces medication costs. Patients who decline to convert medications are less likely to trust their physician.