Psoriasis and chronic obstructive pulmonary disease: a case-control study

Background Previous reports have demonstrated an association between psoriasis and the metabolic syndrome. Chronic obstructive pulmonary disease (COPD) has also been associated with the metabolic syndrome. Objectives To assess the association between psoriasis and COPD in a population-based case-control study. Methods A case-control study was performed utilizing the database of Clalit Health Services, a large healthcare provider organization in Israel. Patients over the age of 20 years who were diagnosed with psoriasis ('cases') were compared with a sample of age- and gender-matched enrollees without psoriasis ('controls') regarding the prevalence of COPD. Group matching was performed. Data on health-related lifestyles and other comorbidities were collected. chi(2) tests, t-tests and logistic regression models were used to compare between study groups. Results The study included 12 502 psoriasis cases and 24 287 controls. The prevalence of COPD was significantly higher in patients with psoriasis [5.7% vs. 3.6%, P < 0.001, odds ratio (OR) 1.63, 95% confidence interval (CI) 1.47-1.81]. A multivariate logistic regression model demonstrated that psoriasis was significantly associated with COPD, after controlling for confounders, including age, sex, socioeconomic status, smoking and obesity (adjusted OR 1.27, 95% CI 1.13-1.42, P < 0.001). Conclusions In this large, population-based case-control study, psoriasis was found to be associated with COPD. Dermatologists caring for patients with psoriasis should be aware of this association, consult an internist or pulmonologist, and advise the patients to stop smoking and reduce additional risk factors for COPD.