Comparison of cognitive performance measures in individuals with systemic lupus erythematosus

Cognitive impairment is a common complaint in SLE, but approaches to measuring cognitive performance objectively vary. Leveraging data collected in a population-based cohort of individuals with validated SLE, we compared performance and potential impairment across multiple measures of cognition.

During a single study visit (October 2019-May 2022), times to complete the Trail Making Test B (TMTB; N=423) were recorded; potential impairment was defined as an age-corrected and education-corrected T-score <35 (>1.5 SD longer than the normative time). A clock drawing assessment (CLOX; N=435) with two parts (free clock draw (CLOX1) and copy (CLOX2)) was also performed (score range: 0-15; higher scores=better performance); potential impairment was defined as CLOX1 <10 or CLOX2 <12. Fluid cognition (N=199; in-person visits only) was measured via the National Institutes of Health (NIH) Toolbox Fluid Cognition Battery and expressed as age-corrected standard scores; potential impairment was defined by a score <77.5 (>1.5 SD lower the normative score).

Participants (mean age 46 years; 92% female; 82% black) had a median (IQR) TMTB time of 96 (76-130) s; median (IQR) CLOX1 and CLOX2 scores of 12 (10-13) and 14 (13-15); and a mean (SD) fluid cognition standard score of 87.2 (15.6). TMTB time and fluid cognition score (ρ=-0.53, p<0.001) were the most highly intercorrelated measures. Overall, 65%, 55% and 28% were potentially impaired by the TMTB test, CLOX task and NIH Toolbox Fluid Cognition Battery, respectively. While there was overlap in potential impairment between TMTB and CLOX, more than half (58%) had impairment by only one of these assessments. Few (2%) had impairment in fluid cognition only.

The TMTB, CLOX and NIH Fluid Cognition Battery each provided unique and potentially important information about cognitive performance in our SLE cohort. Future studies are needed to validate these measures in SLE and explore interventions that maintain or improve cognitive performance in this population.