Rheumatologists have limited tools to assess medication adherence. The extent to which methotrexate (MTX) adherence is overestimated by rheumatologists is unknown.
We deployed an Internet survey to patients with rheumatoid arthritis (RA) participating in a US registry. Patient self-report was the gold standard compared to MTX recorded in the registry.
Response rate to the survey was 44%. Of 228 patients whose rheumatologist reported current MTX at the time of the most recent registry visit, 45 (19.7%) had discontinued (n = 19, 8.3%) or missed ≥ 1 dose in the last month (n = 26, 11.4%). For the subgroup whose rheumatologist also confirmed at the next visit that they were still taking MTX (n = 149), only 2.6% reported not taking it, and 10.7% had missed at least 1 dose.
MTX use was misclassified for 13%-20% of patients, mainly because of 1 or more missed doses rather than overt discontinuation. Clinicians should be aware of suboptimal adherence when assessing MTX response.