The Role of Interleukin 6 on Incident Atrial Fibrillation in COPD Patients

Background: Systemic inflammation might play a role in the observed association between chronic obstructive pulmonary disease (COPD) and atrial fibrillation (AF). Objective: To disentangle the role of interleukin 6 (IL6) in the association between COPD and incident AF. Methods: The Rotterdam Study is a large, population-based cohort study with long-term follow-up. Time dependent Cox proportional hazard models were constructed to study the effect of COPD on incident AF, adjusted for age, sex and pack years of cigarette smoking, and additionally stratified according to IL6 plasma level at baseline. Results: 1369 of 10943 subjects had COPD. During 99242 person years of follow-up, 804 subjects developed AF. The incidence rate of AF was 14 per 1000 person years in COPD and 8 per 1000 person years in subjects without COPD. The adjusted hazard ratio (HR) for COPD subjects to develop AF as compared to subjects without COPD was 1.28 [95%CI 1.04, 1.57]. Within the random subset of subjects with IL6 measurement in plasma at baseline (n=599), COPD subjects with IL6 ≥ median of 1.91 pg/ml, had a 2.5 significantly increased risk to develop AF as compared to subjects without COPD (adjusted HR 2.49 [1.18, 5.28]). The incident AF risk in subjects with COPD below the median IL6 was not increased (adjusted HR 0.53 [0.14, 1.97]). Conclusion: COPD subjects had a 28% increased risk of developing AF. The risk was driven by COPD subjects with an elevated IL6 plasma level.