Pulmonary function, functional capacity and physical activity in patients with SLE: a cross-sectional study

Abstract

Objective SLE is a chronic autoimmune disease. This study aimed to compare pulmonary function, maximal ventilatory capacity assessed by maximal voluntary ventilation (MVV), functional capacity, physical activity level, sleep quality and fatigue between patients with SLE and healthy controls. Methods Respiratory function was assessed using spirometer. Functional capacity was evaluated with the 6-min walk test (6MWT), physical activity with the Global Physical Activity Questionnaire (GPAQ), sleep quality with the Pittsburgh Sleep Quality Index (PSQI) and fatigue with the Fatigue Severity Scale (FSS). Results The cross-sectional study included 25 patients with SLE (21 women, 4 men; mean age 37.00±11.44 years) and 25 healthy controls (20 women, 5 men; mean age 32.24±5.86 years). Groups were similar in age and sex. Compared with healthy controls, patients with SLE had significantly lower forced vital capacity (FVC) (p=0.03), forced expiratory volume in 1 s (FEV1 ) (p=0.01) and MVV (p<0.001). The 6MWT distance and GPAQ total score were also reduced (p<0.01). No differences were observed for FEV₁ /FVC ratio (p=0.75), peak expiratory flow (p=0.32), PSQI (p=0.27) or FSS (p=0.26). In patients with SLE, MVV showed a moderate negative correlation with disease duration (r=−0.585) and a moderate positive correlation with exercise capacity (r=0.618). FEV₁ showed a borderline positive association with exercise capacity (r=0.384). Conclusions Pulmonary function, exercise capacity and physical activity levels were reduced in patients with SLE compared with healthy controls. In addition, pulmonary function parameters were associated with disease duration and exercise capacity, highlighting the importance of early evaluation of respiratory function in patients with SLE.