Risk of chronic obstructive pulmonary disease in healthy individuals with high C-reactive protein levels by smoking status: a population-based cohort study in Korea

PURPOSE: Chronic obstructive pulmonary disease (COPD) is associated with systemic inflammation. We investigated whether elevated baseline serum C-reactive protein (CRP) levels in healthy individuals are associated with the risk of incident COPD by smoking status. PATIENTS AND METHODS: This was a cohort study of 63,260 adult men and women who were older than 40 years, free of COPD at baseline, and underwent health screening from 2002 to 2016 with at least one follow-up visit through December 2016. We investigated the association between baseline high-sensitivity CRP (hsCRP) levels and incident COPD by smoking status, using flexible parametric proportional hazards models and pooled logistic regression analyses. RESULTS: The multivariable-adjusted hazard ratio (95% confidence interval) comparing participants in the 90th to those in the 10th percentile of hsCRP was 1.19 (1.08, 1.31). The corresponding hazard ratio in never, former, and current smokers were 1.07 (0.89, 1.29), 1.22 (1.05, 1.42), and 1.22 (1.05, 1.41), respectively. The association between hsCRP levels and incident COPD had a similar dose–response pattern in former and current smokers, but not in never smokers. CONCLUSION: Higher baseline hsCRP is associated with an increased risk to develop COPD in ever smokers but not in never smokers.