Background Fatigue is a common symptom in systemic lupus erythematosus (SLE) and is associated with poorer quality of life and higher depression scores. Lupus anticoagulant (AcL) refers to a subset of autoantibodies to phospholipids interfering with clotting tests, which major clinical association is thrombosis. Physical activity reduces thrombotic risk in general and is a potential therapeutic strategy for managing fatigue in SLE patients. Purpose: To compare fatigue outcomes according to AcL status in juvenile-onset SLE (jSLE).

Methods A cross-sectional sample of jSLE patients, currently aged ≥ 16 years, completed SF-36, HADS and FSS questionnaires between October 2018- May 2019. The study was approved by the local Ethics Committee. All patients fulfilled both 2012 and 2019 EULAR/ACR classification criteria for SLE. Juvenile-onset was defined as age at diagnosis <18 years. Demographics and clinical characteristics were collected. Statistical analysis was performed with SPSS®.

Results jSLE patients (n=30) were studied (90%female) with median age of 21 years, range 16–35, with mean (SD) age of diagnosis of 15.8 ± 2.1. Mean values (SD) of psychological assessment were: FSS 4.27 ± 1.36; Physical health SF-36 of 66.8(9.9) and Mental health SF-36 of 68.9 (17.5). 56.7% jSLE showed clinically relevant fatigue, 63.3% anxiety and 13.3% depression. Four patients (13.3%) had positive AcL autoantibody. Those had lower Fatigue Severity Scale (FSS) average scores: 3.0 (0.16) vs 4.5 (0.28), comparing to those who were negative for AcL (p=0.036). Likewise, positive AcL jSLE patients had better results in SF-36 Physical Health questionnaires (p=0.034).

Conclusions The relationship between AcL status and fatigue was not previously known. We hypothesize that the present finding may be related to physical activity, a major indication for reducing thrombotic risk and fatigue in jSLE patients. Further studies are needed to address this issue.