OBJECTIVES: Rheumatoid arthritis (RA) is a chronic disease requiring continuous therapy to reach low disease activity targets and to delay its long-term health effects. Effective biologic treatment can be determined in the first year by applying an algorithm to claims data. We investigated year 2 adherence in RA patients who were effectively treated or persistent with initial biologic therapy in year 1.  METHODS: Patients with RA initiating a biologic between January 2009 and December 2012 and with 2 years of continuous enrollment following biologic initiation (index) were identified in the IMS PharMetrics Plus database.  All patients were evaluated for year 1 treatment effectiveness using a validated algorithm and for persistence (gap < 90 days). Year 2 adherence (PDC >80%) on index drug was assessed in both effectively treated and persistent patients. Patients not effectively treated in year 1 due to non-adherence were evaluated separately for year 2 adherence.  RESULTS: Of the 10,374 eligible patients, 76.1% were female, median age was 51 years, and 77.9% were on a previous DMARD. In year 1, 29.7% were effectively treated and 47.5% were persistent.  Among all patients, 46.0% and 33.6% were adherent over the entire one and two year periods, respectively. Effectively treated patients had higher adherence in year 2 compared to non-effectively treated patients, 59.0% vs 31.5% (p<0.0001). Patients persistent during year 1 had significantly higher year 2 adherence compared to their non-persistent counterparts, 60.6% vs. 10.6% (p<0.0001). In patients not effectively treated due to non-adherence, only 12.3% were adherent to their index drug in year 2. CONCLUSIONS: Patients who were initiated on and effectively treated with biologics for RA in year 1 had higher adherence in year 2 compared to non-effectively treated patients.  Establishing effective treatment in year 1 should result in improved adherence and maintained low disease activity in year 2.