Differences in Longitudinal Disease Activity Between Research Cohort and Noncohort Participants with Rheumatoid Arthritis Using Electronic Health Record Data.

Findings suggest that data derived from the EHR were comparable to a cohort across some variables but captured racial/ethnic disparities in long-term outcomes not observed in the cohort study. Research utilizing EHR data in conjunction with cohort studies may provide new opportunities for studying health disparities.