Individual and Community-Level Characteristics and Adherence to Specialty Medications

Background: Understanding risk factors for nonadherence can help specialty pharmacies optimize resources to prevent nonadherence and inform risk-stratification processes. Objective: To determine which individual and community-level characteristics are associated with nonadherence to specialty medications. Methods: We analyzed a cohort of patients enrolled in a prospective randomized controlled trial having filled a specialty medication at least 4 times in the previous 12 months with a proportion of days (PDC) covered < 0.90. We collected patient age, gender, race, medication administration type, therapy start date, home address, insurance type, and online patient portal status from the electronic health record. An ordinal logistic regression model was used to assess the association of nonadherence with individual and community-level patient characteristics. Results: Most patients were female (68%), white (82%), and held commercial insurance (58%) with a median age of 53 (interquartile range [IQR] 40, 64) years. Patients were mostly from the adult rheumatology (35%), multiple sclerosis (20%) and lipid (17%) clinics. Given a 10-year increase in age, patients had lower odds of having lower PDC (odds ratio [OR] = 0.82, 95% confidence interval [CI] = 0.71-0.94, P = 0.005). Patients on therapy greater than or equal to 1 year had half the odds of having lower PDC relative to patients on therapy less than 1 year (OR = 0.52, CI = 0.35 - 0.75, P < 0.001). No statistically significant associations were found between PDC and gender, race, insurance type, route of administration, clinic type, patient portal status, median income, percent receiving government assistance, or percent with no health insurance. Conclusion: Patients with younger age and shorter duration on treatment may be at-risk for lower adherence. Specialty pharmacies may benefit from targeting adherence interventions to these groups.