Insight into intraindividual variability across neuropsychological tests and its association with cognitive dysfunction in patients with lupus

Abstract

ObjectiveDispersion, or variability in an individual’s performance across multiple tasks at a single assessment visit, has been associated with cognitive dysfunction (CD) in many neurodegenerative and neurodevelopmental disorders. We aimed to compute a dispersion score using neuropsychological battery (NB) tests and determine its association with CD in patients with SLE.MethodsCD was defined as a z-score of ≤−1.5 on ≥2 domains of the NB. To compute a type of dispersion score known as the intraindividual SD (ISD), the SD of age-adjusted and sex-adjusted z-scores was calculated for each visit in each patient. To estimate the association between ISD and cognitive status (CD and non-CD), we used multilevel logistic regression, adjusting for clinically important covariates.ResultsA total of 301 adult patients with SLE completed the NB at baseline, 187 of whom were reassessed at 6 months and 189 at 12 months. CD was observed in 35.2% of patients at baseline, 27.8% at 6 months and 28.0% at 12 months. Prior to covariate adjustment, the mean ISD for non-CD was 1.10±0.31 compared with 1.50±0.70 for CD. After adjusting for ethnicity, education, employment, socioeconomic status and anxiety/depression, there was a statistically significant association between ISD and CD (OR for one-unit increase in ISD: 13.56, 95% CI 4.80 to 38.31; OR for 1/10th-unit increase in ISD: 1.30, 95% CI 1.17 to 1.44). Findings were valid across multiple sensitivity analyses.ConclusionThis is the first study to show that patients with SLE who were classified as having CD by the NB had more variability across the NB tests (ie, higher ISD score) compared with those who were not classified as having CD.

Improvement in gait velocity variability after cerebrospinal fluid elimination and its relationship to clinical symptoms in patients with idiopathic normal pressure hydrocephalus

“…33 In addition, intraindividual standard deviation is another indicator that has been used to measure intraindividual variability in previous studies. 36,37 However, intraindividual standard deviation is affected by the mean; the higher the mean, the greater the intraindividual standard deviation. The CV is calculated by dividing the standard deviation by the mean.…”

“…A previous study used CV to measure intraindividual gait velocity variability 33 . In addition, intraindividual standard deviation is another indicator that has been used to measure intraindividual variability in previous studies 36,37 . However, intraindividual standard deviation is affected by the mean; the higher the mean, the greater the intraindividual standard deviation.…”

In-person versus virtual administration of the American College of Rheumatology gold standard cognitive battery in systemic lupus erythematosus: Are they interchangeable?

“…This data included demographic, clinical, and psychiatric characteristics, and the modified American College of Rheumatology neuropsychological battery (ACR-NB), full details are published elsewhere. 3 , 7 Participants in this study have up to four research visits at 0, 6, 12 and 24 months. Inclusion criteria required all participants to meet 2019 EULAR/ACR classification criteria for SLE, 8 to be aged between 18 and 65 years old and to have an adequate level of English to enable completion of the cognitive tasks.…”

Systemic lupus erythematosus phenotypes formed from machine learning with a specific focus on cognitive impairment

“…Our algorithm is based on ACR guidance and results from previous studies that suggest an S.D. of 2 or a z-score cut-off of 1.5 is indicative of impairment on cognitive tests [32,33]. This study had multiple tests within cognitive domains, so to avoid overestimation of CI in a specific domain, the above algorithm was devised.…”