COPD and lung cancer in patients with pemphigus- a population based study.

BACKGROUND: Recent evidence indicates that autoimmunity may contribute to the pathogenesis of chronic obstructive pulmonary disease (COPD). COPD was observed at higher frequency in patients with several autoimmune diseases. The association between pemphigus and COPD has not been evaluated in the past.

OBJECTIVES: To study the association between pemphigus and COPD using a large-scale real-life computerized database.

METHODS: A cross-sectional study was conducted comparing pemphigus patients with age-, sex- and ethnicity-matched control subjects regarding the prevalence of COPD and lung cancer. Chi-square and t-tests were used for bivariate analysis, and logistic regression model was used for multivariate analysis. The study was performed utilizing the computerized database of Clalit Health Services ensuring 4.4 million subjects.

RESULTS: A total of 1985 pemphigus patients and 9874 controls were included in the study. The prevalence of COPD was greater in patients with pemphigus as compared to the control group (13.4% vs. 10.1%, respectively; P < 0.001). In a multivariate analysis adjusting for smoking and other confounding factors, pemphigus was significantly associated with COPD (OR, 1.312-1. 5) but not with lung cancer. Study findings were robust to sensitivity analysis that included patients under pemphigus-specific treatments.

CONCLUSIONS: A significant association was found between COPD and pemphigus. Physicians treating patients with pemphigus might be aware of this possible association. This observation may further support the hypothesis that COPD has an autoimmune component.