Relationship between medication adherence for opioid use disorder and health care costs and health care events in a claims dataset

Introduction: Medication for opioid use disorder (MOUD) has well-documented benefits for treating OUD, though its efficacy depends on patient adherence. We know little about outcomes of MOUD nonadherence compared to treatment regimens without MOUD, and this article aims to address the gap. This analysis focused on office-based MOUD treatment (buprenorphine and naltrexone) to evaluate the long-term impact of adherence on subsequent health care costs and health care events.Methods: With claims data from 2017 to 2019, we used propensity score (PS) weighting to create three comparable cohorts of patients: 1) Adherent: filled MOUD prescription & >= 80 % of days covered by MOUD (N = 1045); 2) Nonadherent: filled MOUD & < 80 % of days covered (N = 1116), 3) did not fill MOUD (N = 16,784). The study defined three time intervals based on a patient's most recent MOUD episode: A 6-month baseline period before initiation of MOUD or random index date for those with MOUD; a 6-month treatment period, during which adherence or nonadherence was established; and a 12-month follow-up period to evaluate outcome measures. The study used generalized PS methodology to examine the effect of proportion of days covered (PDC) as a continuous measure of adherence.Results: Among patients who filled MOUD, adherence to MOUD was significantly predicted by having less severe OUD, being older, having fewer inpatient visits and lower outpatient costs before the start of treatment. Adherent patients displayed significantly lower health care costs in the follow-up period compared to nonadherent MOUD patients, and lower odds of experiencing health care events. The nonadherent MOUD group displayed significantly higher odds of health care events compared to patients who had no evidence of receiving MOUD in claims data (NO-MOUD). Among patients prescribed MOUD, each 10 % increase in PDC was associated with a significant decrease in inpatient/outpatient costs and in odds of health care events.Conclusions: This analysis aligns with previous findings about the importance of maintaining long-term adherence to MOUD in supporting patient outcomes. The results also suggest a novel finding that despite confounder control via PS methods, nonadherent patients display poorer outcomes compared to similar NO-MOUD patients.