What is the prevalence of cognitive impairment in lupus and which instruments are used to measure it? A systematic review and meta-analysis

Objectives: To systematically review the literature on the prevalence of Cognitive Dysfunction (CD) in SLE patients in studies that used a specified neuropsychological instrument.

Methods: This review was prepared with a protocol following the Preferred Reporting Items for Systematic Reviews and Meta-Analysis-Protocols statement. Literature search in Ovid Medline, Embase, and Psyc INFO for articles on CD in adult SLE patients was conducted. Included studies were critically appraised (Newcastle-Ottawa Evaluation Scale) and the Pooled Prevalence (PP) of CD was studied for all instruments. The association between demographics and CD, the risk of CD in SLE compared to healthy subjects and patients with RA, and the course of CD over time were studied narratively whenever sufficient information was available.

Result: Of 8054 references, 670 were selected for detailed review and 78 were included in the final analysis. Comprehensive Battery (CB) was utilized in 35 studies in 2463 SLE patients and PP was 38% (95%; CI: 33-43%). The CD prevalence was higher in NPSLE [PP 39% (95% CI: 24-55%]. Automated Neuropsychological Assessment Metric (ANAM) was utilized in 7 studies in 438 patients (PP of CD 26% (95% CI: 12-42%). Other less frequently utilized tools were the Modified Mini-Mental State Exam (MMSE), Montreal Cognitive Assessment (MoCA), Controlled Oral Word Association Test (COWAT) and The Hopkins Verbal Learning Test-Revised (HVLT-R) and subjective tools and others. The relative risk for CD in SLE was greater when compared to RA and to healthy individuals; RR being 1.80 and 2.80, respectively. Information on demographics and its association with CD was very heterogeneous among studies.

Conclusion: Patients with lupus have a high prevalence of CD. The delay in diagnosis of CD is complex; although caregivers and patients express concerns about cognitive function, testing for CD often imposes administrative and cost burdens. There is an unmet need to identify the best screening, diagnostic metrics of CD. The assessment of cognitive function over time, and the association of demographics with CD, will require further research.