Increased risk of chronic obstructive pulmonary disease in patients with systemic lupus erythematosus: A population-based cohort study

Background: There is increasing evidence that autoimmune disease is associated with development of chronic obstructive pulmonary disease (COPD). We aim to assess the relationship between systemic lupus erythematosus (SLE) and COPD risk in a nationwide population. Methods: We conducted a retrospective cohort study using the catastrophic illness registry of the Taiwan National Health Insurance Research Database (NHIRD). We identified 10,623 patients with SLE newly diagnosed between 2000 and 2010. Each patient was randomly frequency-matched with four people without SLE on age, sex, and index year from the general population. Both cohorts were followed up until the end of 2010 to measure the incidence of COPD. The risk of COPD was analyzed using Cox proportional hazards regression models including age, sex, index year and comorbidities. Results: The overall incidence rate of COPD was 1.73-fold higher in the SLE cohort than in the control cohort (17.4 vs. 10.1 per 10,000 person-years, 95% CI = 1.62-1.84). Age related analysis showed increased incidence of COPD with age in both SLE and control cohorts. However, adjusted HR maximum was observed in the youngest age group (adjusted HR: 4.33, 95% CI, 2.39-7.85) while adjusted HR minimum was witnessed in the oldest age group (adjusted HR: 1.19, 95% CI, 0.85-1.22). Conclusion: Patients with SLE have a significant risk of developing COPD than the control population. Based on the findings from this study, it can be hypothesized that in addition to cigarette smoke SLE may be a determining factor for COPD incidence. However, further investigation is needed to corroborate this hypothesis.