Background/Purpose:

            Few rheumatoid arthritis (RA) patients are managed successfully with a single disease modifying anti-rheumatic drug (DMARD).  This investigation determined the prevalence and clinical characteristics of US veterans with RA treated with a single DMARD in comparison to patients receiving multiple DMARDs.

Methods:

            Patients in the Veterans Affairs RA (VARA) registry, a long-term observational cohort, enrolled at or before four years of disease onset (to allow at least one year of VA-based observation) had DMARD exposures recorded during their first five years of RA.   DMARD exposure was determined by chart annotation for DMARD use occurring prior to VA enrollment and VA pharmacy databases for DMARD exposure after VA enrollment.  Patients who had died within five years of RA diagnosis were excluded.  Patients who received only a single DMARD during the first five years were classified as monotherapy persistent (MONO) and patients receiving more than one DMARD either alone or in combination during the first five years were classified as polytherapy (POLY).   Demographic information, serologic status, smoking history, disease characteristics at the time of VARA enrollment, HLA-DR1 genotyping for shared epitope status, mean multidimensional health assessment questionnaire (MDHAQ), and mean disease activity score (DAS28) during observation were compared in the two groups.  Chart review was conducted on all MONO patients to determine status of RA disease control and if specific reasons were present for not using additional DMARD therapy.

Results:

            Of 2,079 enrolled VARA patients, 486 met enrollment criteria with 50 (10.3%) MONO patients and 436 (89.7%) POLY patients.  MONO DMARDs were methotrexate 36 (72%), hydroxychloroquine 11 (22%), and one (2%) each for leflunomide, sulfasalazine, and etanercept.  Reasons documented for MONO persistence included adequate disease control (n=46; 92%), poor medication adherence (n=3; 6%), and contraindications to other DMARDs because of frequent infections (n=1; 2%).   MONO were older at diagnosis (p<0.02), and were less likely to be seropositive for anti-CCP (p<0.01), less likely to have rheumatoid nodules (p<0.03), and less likely to have DRB1 shared epitope (p<0.05). MONO patients had lower average DAS28 scores (p<0.05) (Table).

Conclusion:

While sustained treatment with a single DMARD during the first five years of RA treatment in US veterans is rare, most of these patients have adequate disease control.  Patients on persistent monotherapy were older at disease onset, less likely to be seropositive, less likely to have rheumatoid nodules, and less likely to carry the DRB1 shared epitope in comparison to patients receiving multiple DMARDs.