Objective: This study examined adherence, discontinuation, and switching of rheumatoid arthritis (RA) biologics over a 1-year period after initiation of the biologic treatment in Medicaid patients with RA.
Methods: The study sample consisted of Medicaid patients with RA in California, Florida and New York who had newly initiated etanercept (n=1359), anakinra (n=267), or infliximab (n=1012) between January 1, 2000 and December 31, 2002. Adherence (proportion of days covered (PDC)≥0.80), discontinuation (90-day continuous gap), and switching (initiation of second biologic within 90days of discontinuation date of index biologic) were measured during the 12-month postindex biologic initiation. Sensitivity analyses were conducted by varying the thresholds to define these measures. Logistic regressions examined the factors associated with RA biologic adherence and discontinuation.
Results: Anakinra users had the lowest mean PDC (0.36) and percent adherent patients (11%) followed by etanercept users (mean PDC: 0.57; % adherent: 32%) and infliximab users (mean PDC: 0.64; % adherent: 43%). All three groups had high discontinuation rates (41% etanercept, 76% anakinra, and 41% infliximab). Few patients who discontinued the index biologic switched to another biologic. Logistic regressions found that patients in Florida had lower odds of being adherent and higher odds of discontinuing their index biologic than patients in California. Anakinra users had lower odds and infliximab users had higher odds of being adherent than etanercept users. Anakinra users had higher odds of discontinuation than etanercept users.
Conclusion: This study highlights the poor adherence to and premature discontinuation without concurrent switching of RA biologics that should raise concern for clinicians as well as payers.
© 2010, International Society for Pharmacoeconomics and Outcomes Research (ISPOR).