Objective: With the growth in patient registries in rheumatic disease research, it is important to validate the collected information. We examined the convergent validity of self-reported medication use for rheumatoid arthritis (RA).
Methods: In the setting of the Brigham Rheumatoid Arthritis Sequential Study (BRASS), a large registry of patients with RA, we examined the agreement between patients' self-report of current and past RA medication use and information from medical records. For a sample of patients in BRASS, these 2 sources of information were compared using the kappa statistic as well as the percent agreement.
Results: The 91 patients selected for assessment were typical of a prevalent RA cohort: >80% were women and the mean disease duration was 16 years. The agreement for current medication use was excellent, ranging from 0.71 for sulfasalazine to 0.96 for methotrexate. However, for past medication use agreement was lower, ranging from 0.13 for methotrexate to 0.74 for aurothioglucose. The weighted kappa for cumulative oral glucocorticoid dose was 0.67.
Conclusion: Self-report of current medication use and cumulative oral glucocorticoid dose appears to have moderate to excellent validity. However, self-report of past medication use may not be valid.