To objectively measure physical activity levels in a cohort of juvenile dermatomyositis (JDM) patients; to compare physical capacity and health-related quality of life in JDM patients and their healthy controls (CTRL) matched by physical activity levels; and to associate physical activity variables with disease-related parameters, physical capacity, and health-related quality of life.
This was a cross-sectional study in which 19 JDM patients and 19 CTRL matched by physical activity levels, age, sex, and body mass index were compared. Physical activity was objectively measured using accelerometers.
In our cohort, only one of the 19 JDM patients (5%) achieved the minimum recommended moderate-to-vigorous physical activity levels (MVPA) (i.e., minimum of 60min/day). JDM showed lower aerobic condition (e.g., VO2peak), muscle function (e.g., timed-stands test), and health-related quality of life in comparison to CTRL (p < 0.05). Sedentary time was positively correlated with disease duration (r = 0.649; p = 0.003), and negatively with VO2peak (r = -0.459; p = 0.048). Moreover, MVPA was negatively associated with disease duration (r = -0.509; p = 0.026), and positively associated with VO2peak (r = 0.797; p < 0.001), and current use of corticoid (r = 0.748; p < 0.001).
Physical capacity and health-related quality of life were reduced in JDM patients when compared with CTRL matched by physical activity levels, suggesting that the disease itself and/or glucocorticoid use may adversely affect overall health in JDM, despite an apparently well-controlled disease. Physical (in)activity correlated with important disease-related and physical capacity parameters, suggesting that sedentary lifestyle may be an important, but preventable, factor associated with poor overall health in JDM.