Association between rosacea severity and relative muscle mass: A cross-sectional study.

Rosacea is thought to be associated with factors involved in metabolic syndrome (MetS). Muscle mass has a beneficial role in preventing MetS, but its link to rosacea remains unknown. We sought to investigate the association between rosacea severity and relative skeletal muscle mass. A cross-sectional study was conducted on subjects who attended a skin check-up program at the Kangbuk Samsung Hospital Health Screening Center between 2014 and 2016. Polarized light photographs of the face were taken and evaluated by two dermatologists. Skeletal muscle mass index (SMI, [%] = total skeletal muscle mass [kg] / bodyweight [kg] × 100) was estimated using a bioelectrical impedance analyzer. A logistic regression model was used to evaluate an association between SMI and rosacea. Of 110 rosacea subjects who were finally enrolled, 17 (15.5%) and 93 (84.5%) were classified as having papulopustular and erythematotelangiectatic rosacea, respectively. Categories of SMI comprised the following tertiles: 22.86-38.40%, 38.41-43.44% and 43.45-80.65%. In severity, compared with mild rosacea (75.5%), moderate rosacea (24.5%) incrementally increased as SMI decreased (Ptrend < 0.01). Severe rosacea was not observed. After adjustment for age and sex, odds ratios (95% confidence intervals) for moderate rosacea comparing SMI tertiles 1 and 2 to the highest tertile (reference) were 5.66 (1.22-26.20) and 4.43 (1.12-17.55), respectively (Ptrend = 0.03). This association was present in women with marginal significance (Ptrend = 0.06), but not in men. Relative muscle mass is negatively associated with an increased risk of more severe rosacea, suggesting that skeletal muscle can have a protective effect on rosacea exacerbation.