IL6 and chronic obstructive pulmonary disease: The results of subgroup analysis showed that probiotics were able to significantly decrease IL-6 in both no steroid-resistant COPD animals (SMD = -5.75, 95% CI: -7.63 to -3.87, z = -5.985, p = 0.000 < 0.05) and steroid-resistant COPD animals (SMD = -16.31, 95% CI: -22.92 to -9.70, z = -4.837, p = 0.000 < 0.05).