Medication adherence and persistence over time with self-administered TNF-alpha inhibitors among young adult, middle-aged, and older patients with rheumatologic conditions

Objective: Self-injectable TNF inhibitors are increasingly used early in the chronic treatment of moderate to severe rheumatologic conditions. We estimated medication adherence/persistence over time following initiation in young adult and older adult patients with rheumatoid arthritis, ankylosing spondylitis or psoriatic arthritis. Methods: We conducted a retrospective cohort study of patients aged 18+ years newly initiating etanercept, adalimumab, certolizumab pegol, or golimumab using the Truven Health MarketScan Database between 2009 and 2013. Pharmacy dispensing data were used to calculate 12-month medication possession ratios (MPR) and determine adherence (MPR >= 0.80) for up to 3 years after starting therapy. Persistence over each 12-month interval was defined as not having a >= 92-day treatment gap. Multivariable generalized estimating equation models were used to calculate odds ratios (OR) and robust 95% confidence intervals (CI) for associations between patient characteristics and repeated adherence/persistence measures over time. Results: Among 53,477 new users, 14% were young adults (18-34 years), 49% middle-aged (35-54 years), and 37% older adults (55 + years). Overall, 37% of patients were adherent and 83% were persistent in the first year of therapy. The lowest adherence (17%) and persistence (70%) were observed among young adult patients by Year +3. Compared to older adults, middle-aged (OR = 0.73, 95% CI: 0.71-0.76) and young adults (OR = 0.50, 95% CI: 0.47-0.53) were less likely to be adherent. Higher Charlson comorbidity scores, hospitalizations, and emergency department visits were associated with non-adherence/non-persistence. Conclusions: We observed low adherence to self-administered TNF inhibitors but most patients remained persistent over time. Further efforts to improve adherence in young adults and patients with greater comorbidity are needed. (C) 2017 Elsevier Inc. All rights reserved.