Developing an Integrated Longitudinal Dataset for Patient-Centered Outcome Measures in Cost-Related Medication Nonadherence

BACKGROUND: Cost-related medication nonadherence (CRN) is an important patient-centered outcome measure. Longitudinal follow-up of CRN is rare. OBJECTIVE: We propose to develop a novel integrated dataset to study CRN longitudinally. RESEARCH DESIGN: A dataset of 2000 Medicare beneficiaries at high risk of hospitalization surveyed quarterly on CRN and followed up individually for 8 quarters between 2013 and 2018 was linked to Medicare files. A metric of CRN categorizing persistent, intermittent, and transient CRN during the 8 quarters was developed. An ordered logit model and a logit model were developed to assess the factors influencing CRN overall and persistent CRN, respectively. RESULTS: A total of 1761 patients were included in the analysis, among whom 869 (49.3%) reported CRN at least once in the 8-quarter study period, 178 (10%) reported persistent CRN, 395 (22.4%) reported intermittent CRN, and 296 (16.8%) reported transient CRN. The conditional effect in the logit model for persistent CRN revealed that baseline dual eligibility was negatively associated (adjusted odds ratio = 0.45, P < 0.01) and depression positively associated (adjusted odds ratio = 1.55, P = 0.01) with persistent CRN. The marginal analysis in the ordered logit model revealed a clear pattern of higher probabilities of persistent and intermittent CRN at younger ages while transient CRN was flat. Among the 252 subjects who were deceased, 31 (12.3%) reported persistent CRN, compared with 147 (9.74%) who were alive (P = 0.21 by χ(2) test). CONCLUSIONS: A significant number of patients reported persistent CRN, including those who were at the end of life. Research is critically needed to understand behavioral patterns among the younger Medicare population.