Prevalence and determinants of seborrhoeic dermatitis in a middle-aged and elderly population: the Rotterdam Study

Background Seborrhoeic dermatitis is a chronic relapsing inflammatory skin disease with unclear pathophysiological mechanisms. Objectives To establish which lifestyle and physiological determinants are associated with seborrhoeic dermatitis. Methods Seborrhoeic dermatitis was diagnosed by a trained physician during a full-body skin examination within the Rotterdam Study, a prospective population-based cohort study in middle-aged and elderly people. The current design is a comparative cross-sectional study embedded in the Rotterdam Study. Potential factors were identified from the literature and analysed in a multivariable logistic regression, including: age, sex, obesity, skin colour, stress, depression, education level, hypertension, climate, xerosis cutis, alcohol and tobacco use. Results Of the 5498 participants, 788 participants were diagnosed with seborrhoeic dermatitis (14.3%). We found associations between seborrhoeic dermatitis and male sex [adjusted odds ratio (OR) 2.09, 95% confidence interval (CI) 1.77-2.47], darker skin (adjusted OR 0.39, 95% CI 0.22-0.69), season (summer vs. winter: adjusted OR 0.63, 95% CI 0.48-0.82) and generalized xerosis cutis (adjusted OR 1.41, 95% CI 1.11-1.80). Conclusions Seborrhoeic dermatitis is one of the most common inflammatory dermatoses in middle-aged and elderly individuals, especially during winter. Men, and people with a light and dry skin were most likely to have seborrhoeic dermatitis.