Numerous studies report that significant discordance exists between patient and provider [physician] measures of rheumatoid arthritis (RA). We examined whether health literacy explains this discordance.
We recruited English-speaking adult patients with RA for this cross-sectional study. Subjects completed 2 versions of patient global assessments of disease activity (PTGA), using standard terminology from the Multi-Dimensional Health Assessment Questionnaire (MDHAQ) and the 28-joint count Disease Activity Score 28 (DAS28). The provider global assessment (MDGA) was also obtained. The discrepancy between PTGA and MDGA was calculated as the absolute difference between these assessments. We used validated instruments [Short Test of Functional Health Literacy in Adults (S-TOFHLA) and Rapid Estimate of Adult Literacy in Medicine (REALM)] and linear regression to determine whether health literacy predicts disease measure discrepancy.
The study included 110 subjects. Limited health literacy was a common finding by both the REALM and S-TOFHLA. PTGA and MDGA showed fair to good correlation (r = 0.66-0.68), although both versions of the PTGA were significantly higher than MDGA by the t-test (p < 0.001). The S-TOFHLA and REALM both were associated with the absolute difference between the MDGA and PTGA by linear regression, and results remained statistically significant in multivariate analysis.
Health literacy was independently associated with the extent of discrepancy between PTGA and MDGA in English-speaking patients with RA at an urban clinic. This finding should influence our interpretation of disease measures.