ANXA1 and chronic obstructive pulmonary disease: Subgroup analysis showed that ANXA1 levels were further decreased in COPD patients with frequent moderate exacerbation as compared with that in those without frequent moderate exacerbation (0.58 ± 0.36 vs. 1.68 ± 1.9 ng/ml, p = 0.002, Fig. 4f) or healthy non-smokers (2.97 ± 1.9 ng/ml, p = 0.001).