ADIPOQ and chronic obstructive pulmonary disease: It showed that in that subgroup, the circulating adiponectin levels were still higher in COPD patients than those in controls who were matched for important potential confounders (SMD: 1.09, 95% CI [0.70–1.49], P < 0.001; I2 = 91.3%, P < 0.001; Figure 4).