To determine the extent to which cognitive dysfunction (CD) observed in patients with systemic lupus erythematosus (SLE) exceeds that seen in a matched control group of patients with rheumatoid arthritis (RA), and to estimate the prevalence of CD in SLE in a community-based sample.
A random subsample of 31 patients with SLE was compared to patients with RA matched by age, sex, and race and derived from the same patient population. Cognitive function was assessed by the Automated Neuropsychological Assessment Metrics (ANAM). The primary outcome was the total throughput score (number of correct responses divided by the time taken for those responses averaged over all subtests), adjusted for premorbid intelligence, neuromuscular efficiency, disease activity, damage, depression, fatigue, and health-related quality of life.
There were no statistically significant differences in mean throughput scores between patients in the SLE and RA groups in any subtest of the ANAM or in the total throughput score. The frequency of CD, defined as either total scores > 1.5 SD below the mean of the RA population, or 4 or more ANAM subtests each > 1.5 SD below the RA mean, was similar in patients with SLE and in RA controls.
We found no differences in cognitive function between patients with SLE and RA, suggesting that the CD found in some patients with SLE may represent the consequences of a chronic and/or inflammatory disease rather than SLE-related central nervous system damage.