Risk factors for erysipelas and cellulitis: A national cohort study

• A nationwide study examining risk factors for erysipelas and cellulitis. • Familial associations of erysipelas and cellulitis were observed. • Sociodemographic factors are associated with these skin infections. • Obesity and diabetes have a two-fold increased risk of skin infections. • Alcoholism and chronic respiratory disease are also risk factors for skin infections. Examining risk factors for erysipelas and cellulitis in adults using national registers and primary healthcare data. A nationwide open cohort study including 7,580,645 Swedish men and women (2001–2018) was conducted. The outcomes were erysipelas and cellulitis (skin infections). The predictors were sociodemographic factors (sex, age, education- and family income levels, region of residency and country of origin), family history of skin infections, and comorbidities—alcoholism, chronic respiratory disease, diabetes, and obesity. Cox regression models were used to estimate hazard ratios (HRs) and 95% confidence intervals (CIs). Familial association of erysipelas (HR 1.28; 95% CI, 1.26–1.30) and cellulitis (1.23; 1.20–1.25) were observed. Several sociodemographic factors were associated with erysipelas and cellulitis. Men had higher risk of erysipelas (1.16; 1.15–1.17) but lower cellulitis risk (0.95; 0.94–0.96) compared to women. Comorbidities were associated with erysipelas and cellulitis, e.g., diabetes mellitus was associated with HRs of 2.00 (1.97–2.02) for erysipelas and 2.23 (2.19–2.27) for cellulitis. This nationwide study identified familial and sociodemographic associations of erysipelas and cellulitis. Alcoholism, chronic respiratory disease, diabetes mellitus, and obesity were associated with erysipelas and cellulitis.