Fatigue is independently associated with disease activity assessed using the Physician Global Assessment but not the SLEDAI in patients with systemic lupus erythematosus

Objectives To analyse whether reported fatigue, one of the most challenging manifestations of systemic lupus erythematosus (SLE), may bias the assessment of disease activity in SLE according to the Physician Global Assessment (PGA). Methods Patients from the Lupus BioBank of the upper Rhein database, a cross-sectional multicentre collection of detailed clinical and biological data from patients with SLE, were included. Patients had to fulfil the 1997 American College of Rheumatology criteria for SLE and the PGA (0-3 scale) at the time of inclusion had to be available. Fatigue was assessed according to the Fatigue Scale for Motor and Cognitive Functions. Univariate and multivariate regression models were built to determine which variables were associated with the PGA. Results A total of 350 patients (89% female; median age: 42 years, IQR: 34-52) were included. The median Safety of Estrogens in Lupus Erythematosus National Assessment-Systemic Lupus Erythematosus Disease Activity Index (SELENA-SLEDAI) score was 4 (IQR: 2-6). Of these 350 patients, 257 (73%) reported significant fatigue. The PGA (p=0.004) but not the SELENA-SLEDAI (p=0.43) was significantly associated with fatigue. Both fatigue and SELENA-SLEDAI were independently associated with the PGA in two different multivariate models. Conclusion Fatigue is independently associated with disease activity assessed using the PGA but not the SLEDAI. These findings highlight the fact that the PGA should capture only objectively active disease manifestations in order to improve its reliability.