Background/Purpose:   Adherence to medication is crucial to the maximum therapeutic benefit of biologic treatment. The plethora of currently approved biologic agents makes comparison of the various medications more difficult, particularly when drug dosing and administration schedules vary. This study used administrative claims to investigate real world utilization and adherence patterns of subcutaneous (subQ) biologic treatment in a population of patients with RA.

Methods: The earliest incident adalimumab (ADA), certolizumab (CER), etanercept (ETA), and golimumab (GLM) biologic cycles of treatment were identified in the Truven MarketScan® and Optum Clinformatics™ research databases for adult patients with an RA diagnosis (ICD-9: 714.xx) between 2009 – 2013. Members were required to have ≥ two index biologic fills, and continuous eligibility for at least 6 months prior to biologic initiation. Members were followed until the end of their treatment, eligibility was lost, or the end of the data was reached. Utilization measures included biologic placement, treatment gaps measured as the number of days between expected refill dates, dose escalation, defined as any appearance of a twofold increase in dose from the starting dose, and medication adherence assessed by the proportion of days’ covered (PDC).  Members with 80% of the days in their treatment period covered by the index medication were categorized as adherent. One-way ANOVA and chi-square tests of equality of proportions were conducted to assess group differences.

Results: Modal monthly calculated dosages were in line with recommended prescribing guidelines for all four treatments (Table 1).  GLM and CER were significantly less likely to be administered as a first line biologic compared to ADA and ETA; however GLM members were more likely to be adherent (ps < 0.05).  ADA and GLM members displayed the greatest refill consistency within the Truven database as evidenced by lower gaps between refills (ps < 0.05).  Consistent with the label, ADA cycles were more likely to show a dose escalation (ps < 0.001).  Nearly two-thirds of all treatment cycles persisted for ≥ 6 months, with the greatest proportion from the ETA group across both databases. (p < 0.001).  

Conclusion:   Significant differences in biologic utilization patterns were observed among the four treatment groups. ADA and ETA were the most common first line biologics, though GLM cycles were associated with greater refill consistency and levels of adherence. These findings have implications for healthcare decision makers interested in quality improvement or optimization of adherence in patients treated with subcutaneous biologic therapies.