IL6 and chronic obstructive pulmonary disease: Since previous studies have shown higher levels of serum IL-6 in people with COPD compared to those without COPD (19–22), we first examined the association between rs2228145 and baseline serum IL-6 level in the ECLIPSE study, finding an increase in IL-6 level per copy of the minor allele after adjustment for age, COPD status, smoking status, smoking amount and ancestry (β = 0.15 [95% CI: 0.08, 0.23]).