Daily life physical activity in patients with chronic stage IV sarcoidosis: A multicenter cohort study.

Background and Objectives: Little is known about the consequences of chronic sarcoidosis on daily life physical activity (DL _PA ). The aim of this prospective study was to measure DL _PA in patients with chronic sarcoidosis and to determine its relationship to clinical and functional parameters.
Methods: Fifty-three patients with chronic sarcoidosis and 28 healthy control subjects were enrolled in this multicenter prospective study. Two markers of DL _PA (number of steps walked per day [SPD]) and total daily energy expenditure (TEE) were assessed for five consecutive days with a physical activity monitor. Pulmonary function, aerobic capacity (maximal oxygen uptake [VO ₂ max]), exercise capacity (6-min walk test [6MWT]), and quality of life (self-reported questionnaires) were also evaluated. Comparisons of DL _PA parameters between the two groups were performed using an analysis of covariance adjusted for age, sex, and body mass index (BMI). Relationships between DL _PA parameters and patient characteristics were assessed in multivariable linear regression models.
Results: Patients with sarcoidosis walked significantly fewer SPD than did the control subjects (6395 ± 4119 and 11 817 ± 3600, respectively; P  < 0.001 after adjustment for age, BMI, and sex). TEE was not significantly different between patients with sarcoidosis and healthy controls (median [interquartile range]: 2369 [2004-2827] and 2387 [2319-2876] kcal/day, respectively, P  = 0.054 adjusted for age, BMI, and sex). SPD showed significant positive correlations with 6MWT distance (Pearson's correlation, r  = 0.32, 95% confidence intervals [95%CI] = 0.06, 0.55; P  = 0.019), VO ₂ max ( r  = 0.44, 95%CI = 0.17, 0.65; P  = 0.002), and Visual Simplified Respiratory Questionnaire score ( r  = 0.44, 95%CI = 0.19, 0.64; P  = 0.001), and a significant negative correlation with modified Medical Research Council questionnaire score ( r  = -0.38, 95%CI = -0.60, -0.10; P  = 0.009). TEE was significantly correlated with BMI ( r  = 0.38, 95%CI = 0.13, 0.59; P  = 0.004), forced expiratory volume in 1 second ( r  = 0.55, 95%CI = 0.33, 0.71; P  < 0.001), total lung capacity ( r  = 0.44, 95%CI = 0.18, 0.64; P  = 0.001), and forced vital capacity ( r  = 0.56, 95%CI = 0.34, 0.72; P  < 0.001). In multivariable analysis, SPD remained associated only with VO ₂ max.
Conclusion: Patients with chronic sarcoidosis appear to have reduced DL _PA mainly because of compromised VO ₂ max.