Self-Reported Physical Activity Is Associated with Lupus Nephritis in Systemic Lupus Erythematosus: Data from KORean Lupus Network (KORNET) Registry

PURPOSE: The aim of this study was to identify the associations among physical activity, disease activity, and organ damage in patients with systemic lupus erythematosus (SLE). MATERIALS AND METHODS: A total of 415 patients with SLE were consecutively enrolled from the KORean lupus Network (KORNET) registry. This registry assessed clinical features, disease activity [Systemic Lupus Erythematosus Disease Activity Index 2000 (SLEDAI-2K)], and organ damage [Systemic Lupus International Collaborating Clinics/American College of Rheumatology (SLICC/ACR) Damage Index (SDI)] upon enrollment in the study. Self-reported physical activity was measured by the International Physical Activity Questionnaire. Statistical analyses were conducted using the Mann-Whitney U test and multivariate logistic regression analysis. RESULTS: A significant difference in vigorous activity was noted between patients with lupus nephritis (LN) (n=93) and those without LN (n=322) (p=0.012), but not in moderate and walking activities. In contrast, no differences in physical activity, walking, moderate, and vigorous intensity, according to SLEDAI-2K and SDI were found. In addition to younger age (p=0.032), high physical component summary of SF-36 (p=0.004) and SLEDAI-2K (p=0.038), and less vigorous physical activity were associated with LN (p=0.024). However, cardiovascular disease was not associated with physical activity in SLE patients. CONCLUSION: This study showed that patients with LN had less vigorous physical activity than patients without LN. The results suggest that lupus nephritis might be associated with physical activity.