In addition, a subgroup analysis of asthma disease status showed that IL-6 levels were increased in stable (SMD 0.69, 95% CI 0.28–1.09, P = 0.009) and exacerbation asthma (SMD 2.15, 95% CI 1.79–2.52, P < 0.00001) patients. This evidence concerns the gene IL6 and asthma.