Cross-sectional correlation of single-item health literacy screening questions with established measures of health literacy in patients with rheumatoid arthritis.

Research suggests that health literacy (HL) is associated with rheumatoid arthritis (RA) patients' functional status. Single-item health literacy screening (SILS) questionnaires may establish patients' HL; however, the wording of SILS may be misinterpreted by RA patients as a query regarding physical limitations. Despite this threat to validity, multiple publications have employed the SILSs as a measure of health literacy. We assessed the construct validity of two SILS's versions by correlating scores with standardized HL measures. English-speaking adult RA patients at a hospital serving low-income patients were enrolled in a cross-sectional study. Subjects completed two SILS versions, as well as two longer HL measurement tools [short test of functional health literacy in adults (s-TOFHLA) and the rapid estimate of adult literacy in medicine (REALM)]. Spearman correlation was used to compare these tools. The study enrolled 110 subjects. There was a good correlation between the two SILS versions (r = 0.705). The correlation of SILS2 and REALM or s-TOFHLA was less robust. The distribution of scores within each SILS2 category demonstrated substantial variation. The SILS2 has construct validity in the assessment of HL in patients with RA, though its correlation with traditional methods of assessing HL is weak.