Discrepancy between subjective and objective measures of cognitive impairment in patients with rheumatoid arthritis

This study explored the discrepancy between perceived cognitive dysfunction and computerized neuropsychological test performance in Korean patients with RA. Individuals with RA were recruited by their rheumatologists during follow-up visits at one hospital in Korea. After getting signed consents, a trained research nurse assessed participants with a range of physical, psychosocial, and biological metrics. Subjective cognitive dysfunction was assessed using the Perceived Deficits Questionnaire (PDQ; range 0-20). Objective cognitive impairment was assessed using a set of 6 computerized neurocognitive tests yielding 12 indices covering a range of cognitive domains. Subjects were classified as 'impaired' if they performed 1 SD below age-based population norms on each test. A total cognitive function score was calculated by summing the transformed scores (range 0-12). Multiple linear regression analyses determined the relationship of total cognitive function score with PDQ score, controlling for disease activity, functional limitations, and psychological factors. Forty subjects (mean ± SD age: 63.1 ± 11.4 years) were included. Mean ± SD scores of total cognitive function and PDQ were 7.3 ± 2.7 (2-12) and 11.8 ± 5.1 (5-25), respectively. In multivariate analysis, there was no significant relationship between total cognitive function score and PDQ score. However, depression and sleep quality (β = 0.37, p = 0.025; β = 0.17, p = 0.034) were significantly associated with PDQ score. The findings emphasize the gap between subjective and objective measures of cognitive impairment and the importance of considering psychological factors within the context of cognitive complaints in clinical settings.