Association between psoriasis and the metabolic syndrome. A cross-sectional study

Background: Previous reports have shown an association between inflammatory diseases such as systemic lupus erythematosus or rheumatoid arthritis and the metabolic syndrome. Recent data demonstrate that psoriasis is an inflammatory disease, suggesting that psoriasis may be one of the components of the metabolic syndrome.

Objective: To assess the association between psoriasis and the metabolic syndrome.

Methods: A cross-sectional study was performed utilizing the database of the Clalit Health Services. Case patients were defined as patients with a diagnosis of psoriasis vulgaris. Controls were randomly selected from the list of Clalit Health Services enrollees. The proportions of components of the metabolic syndrome (ischemic heart disease, hypertension, diabetes, obesity and dyslipidemia) were compared between case and control patients by univariate analyses. chi(2) tests were used to compare categorical parameters between the groups. Logistic and linear regression models served to measure the association between psoriasis and the metabolic syndrome.

Results: The study included 16,851 patients with psoriasis and 48,681 controls. In the case group, there were 8,449 men (50.1%) and 8,402 women (49.9%), with a mean age of 42.7 years (SD = 20.3, range = 2-111). Diabetes mellitus was present in 13.8% of the patients with psoriasis as compared to 7.3% of the controls (p < 0.001). Hypertension occurred in 27.5% of the patients with psoriasis and in 14.4% of the controls (p < 0.001). Obesity was present in 8.4% of the patients with psoriasis as opposed to 3.6% of the controls (p < 0.001). Ischemic heart disease was observed in 14.2% of the patients with psoriasis as compared to 7.1% of the controls (p < 0.001). Multivariate models adjusting for age, gender and smoking status of the patients demonstrated that psoriasis was associated with the metabolic syndrome (OR = 1.3, 95% CI = 1.1-1.4), ischemic heart disease (OR = 1.1, 95% CI = 1.0-1.2), diabetes mellitus (OR = 1.2, 95% CI = 1.0-1.3), hypertension (OR = 1.3, 95% CI = 1.2-1.5) and obesity (OR = 1.7, 95% CI = 1.5-1.9).

Limitations: The study is designed as a case-control study, thus an association alone was proven and not causality.

Conclusion: Our findings demonstrate a possible association between psoriasis and the metabolic syndrome. Appropriate treatment of the metabolic syndrome may be an important part of the management of patients with psoriasis.