Background/Purpose:

Most rheumatoid arthritis (RA) registries capture information about medication use using data captured at office visits. The extent to which this information may be misclassified or over-estimated for RA medications, including methotrexate (MTX), is unknown.

Methods

In 1Q and 2Q 2014, we conducted an Internet-based survey of RA patients participating in the comparative effectiveness CERTAIN substudy (n= 2485 unique biologic initiations as of April 2014) nested within the Corrona RA registry. Patients were eligible if they had valid email addresses (n=991 unique patients)..  Patients were asked whether they were taking methotrexate and if so, how many MTX doses in the last 4 weeks they had taken. Patient report from the survey was used as the gold standard and compared to the use of MTX routinely recorded in the registry at the previous and next office visits. A subgroup analysis was conducted for the additional patients who had not yet had a follow-up visit in the registry. A sensitivity analysis restricted the interval of time between the survey and the previous registry visit to <=6 months to assess whether misclassification of MTX use was related to the interval of time between registry visits.

Results

A total of 433 patients answered the survey, a 44% response rate. Overall, survey respondents had mean (SD) age 53.5 (12.5) age, were  80.8% women, and 78.9% RF+ or CCP+. Mean (SD) disease activity measured at the previous visit using CDAI was 17.4 (14.7). Of the subgroup of patients who were recorded at the prior and next registry visit as consistently being on MTX (n=88), only 1 (1%) of patients indicated that they were not actually taking MTX. However, 10% of the remaining patients indicated that they had missed one or more doses in the last 4 weeks. Results were similar for the 111 additional patients who had not yet had a follow-up registry visit; 15% indicated that they had missed one or more doses in the last 4 weeks. Of the patients who missed one or more doses in the last 4 weeks, approximately one-third to one-half missed more than 1 dose. Results were robust in sensitivity analysis.

Conclusion

In this large U.S. registry, MTX use was generally ascertained accurately at office visits. However, up to 15% of patients recorded by their rheumatologist to be on MTX had missed doses in the last month. Clinicians need to be aware of potentially suboptimal adherence when assessing response to MTX. Further efforts to detect low adherence to MTX and identify reversible barriers to adherence are needed.

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ACR Meeting Abstracts - https://acrabstracts.org/abstract/physician-awareness-of-suboptimal-patient-adherence-to-mtx-results-from-a-large-u-s-rheumatoid-arthritis-registry/