The impact of cognitive impairment on Health-Related Quality of Life in Systemic Lupus Erythematosus: a cross-sectional study

Abstract Purpose: To correlate the cognitive functions evaluated by the Symbol Digit Modalities Test (SDMT)with the principal clinical features and Health-related Quality of Life (HRQoL) measures of SLE. Material and methods: We recruited consecutive outpatients with SLE from a third-level Lupus Clinic in Italy to undergo neuropsychological evaluation using SDMT and the LupusQoL-IT as HRQoL questionnaire. Patients were defined as either neuropsychiatric-SLE (NPSLE) or as non-neuropsychiatric-SLE (non-NPSLE); they were also classified as cognitive-impaired and cognitive-preserved based on SDMT score alteration corrected for age, gender and education. In this cross-sectional study we included and studied 140 consecutive patients; 30 patients had NPSLE. Inclusion criteria were 4 or more ACR criteria for SLE, exclusion criteria were non–italian speaking, ocular disease interfering with reading capacity, the onset of any major medical condition (e.g. requiring hospitalization) or overt new neuropsychiatric event within the study period. Results: The mean SDMT score was 41.4±12.8. Alteration of SDMT score was detected in 29.9% of patients. Pearson test showed a correlation between SDMT score and Systemic Lupus International Collaborating Clinics/ACR Damage Index (SLICC/ACR-SDI) score (r:-0.373, p< 0.001) and specific HRQoL domains. Cognitive-impaired and cognitive-preserved patients showed a significant difference in physical health (p=0.03), pain (p=0.04) and planning (p=0.02) domains of the HRQol. A multiple linear regression (dependent variable: SDMT score) revealed a relationship with SLICC/ACR-SDI (p=0.005) and with other clinical features, after adjustment. SDMT score was significantly more frequently altered among patients with NPSLE (p=0.009) and the mean was significantly different in comparison to non-NPSLE patients (p=0.01). Conclusions: Our data demonstrate the correlation between cognitive impairment captured using SDMT and HRQoL of SLE patients and show a correlation of measures such as SLICC/ACR-SDI with SDMT score.