CAT and chronic obstructive pulmonary disease: In subgroup analyses by patient type, changes in FEV1 in asthmatic patients (WMD = 9.61%, 95% CI: −7.79, 27.02), CAT levels in COPD patients (WMD = 0.00 U/mL, 95% CI: −0.01, 0.01), thiol levels in patients with asthma (WMD = 0.019 μmol/ml, 95% CI: −0.079, 0.117) and COPD (WMD = −0.001 μmol/mL, 95% CI: −0.015, 0.012), and IL‐10 levels in asthmatic patients (WMD = 1.63 pg/mL, 95% CI: −1.39, 4.65) were significantly altered.