OBJECTIVES: Studies have shown better response for anti-TNFs (aTNF) in combination with non-biologic DMARDs (nbDMARD), than as monotherapies in rheumatoid arthritis (RA) (Nixon 2007). Non-adherence to nbDMARDs prescribed in combination with aTNFs may reduce the benefit of aTNFs.  We examined the use of aTNF monotherapy and adherence with nbDMARDs in RA patients receiving combination aTNF+nbDMARDs. METHODS: We conducted claims analysis of adult RA patients in a US managed care plan, initiating aTNF agents between Jan’06-Dec’10. aTNF initiators were classified as ‘biologic-naïve’ or ‘previously-exposed’ based on prior biologic use, and followed until discontinuation of that aTNF or disenrollment. Proportion of patients receiving aTNF as monotherapy (no nbDMARD during aTNF follow-up) was determined. In combination therapy patients (received nbDMARD during aTNF follow-up), adherence to nbDMARDs was defined as the percent of days that patients received any nbDMARD while they were receiving the aTNF agent. RESULTS: Of 7,074 biologic-naïve RA patients initiating an aTNF, 27% received it as monotherapy and 73% in combination with nbDMARDs. Of 2,690 aTNF patients previously exposed to biologics, 31% received monotherapy and 69% in combination with nbDMARDs. Only 42% of patients receiving aTNF monotherapy vs. 89% of combination therapy patients had filled a nbDMARD prescription during the 6 months prior to initiating the aTNF. Among biologic-naïve combination therapy patients, 52% of patients adhered with nbDMARD therapy less than 80% of the time while receiving aTNFs; 32% of the patients had less than 60% adherence. Results were similar for aTNF patients previously exposed to biologics. CONCLUSIONS: We found that up to 31% of patients receiving an aTNF agent for RA received it as monotherapy, and a substantial proportion of those receiving combination therapy had less than 60% adherence with nbDMARDs. Some of these patients may have sub-optimal outcomes, as suggested by evidence that RA patients receiving aTNFs in combination with nbDMARDs have better response.