Cognitive impairment (CI) is a neuropsychiatric manifestation of SLE, and has been quoted to occur in SLE at rates between 20-80%. However, screening and diagnosis of CI may be delayed and monitoring for this condition may not be well-developed. Part of this issue likely has to do with the need for a screening tool in the ambulatory setting that could be used to screen for CI.
Several tools have been evaluated, including the Mini-Mental State Examination (MMSE), the Montreal Cognitive Assessment (MoCA), the Hopkins Verbal Wording Test Revised (HVWT-R), as well as the Controlled Oral Word Association Test (COWAT). The HVWT-R involves word recall, and the COWAT involves naming as many words as possible starting with a certain letter of the alphabet. The aim of the current study was to look at the validity of the MoCA as well as the MMSE as screening tests in SLE for CI. It also looked at associated variables (e.g. depression, education level) as these factors may influence cognitive function.
The study involved patients recruited from the Toronto Lupus Centre who came for their regular appointments between February 2014-June 2015; these patients had a diagnosis of SLE and were over 18 years of age. There were two phases to the study – the first involved a phone assessment where the HVLT-R and COWAT were administered, and the second phase involved an in-clinic assessment where the MoCA and MMSE were given. Other variables, including intelligence screening, depression and anxiety questionnaires, were also administered, and logistic regression analyses were used to correct for these associations.
The study group consisted of 98 SLE patients, mostly female, average age at assessment 48 and age at diagnosis 30, with an average disease duration of 19 years and education level of 15 years. Most patients had a SLEDAI score of <4, indicating mild disease. Overall, it was felt that this study group was representative of the general SLE population.
The prevalence of CI was 38% according to the HVLT-R and 48% with the MoCA; the prevalence were lower using the other screening tools. In patients with CI, scores on the MoCA were lower in the areas of attention, language and delayed recall, compared to scores from normal controls taken from the literature.
The MoCA was more sensitive than the MMSE for detecting cognitive impairment, but the MMSE was more specific. In addition, the MoCA had a higher negative predictive value for CI. The HVLT-R had moderate correlation with MoCA and less with the MMSE.
When controlling for other variables, those with CI were more likely to endorse symptoms of depression in a univariate analysis, but this did not hold up in the multivariate analysis. Interestingly, patients with a longer duration of SLE and more years of education had lower rates of CI. Overall, each year of education reduced the risk of CI by 17%.
There were limitations to this study. Firstly, there was lack of a gold standard screening test for CI in SLE for comparison. In addition, most patients had long-standing disease, so there was lack of an earlier disease cohort to compare the findings to. In addition, the control population was taken from the literature.
The authors concluded that CI was present in 48% of their patients using the MoCA as an assessment tool; they also concluded that the MoCA may be an appropriate screening test for CI in SLE patients, and that increased years of education was protective against the development of CI in SLE patients.