The GSTM1(−)/GSTT1(−) genotype was present in 17 (8.5%) COPD patients and 10 (5%) healthy individuals (OR = 1.13, 95% CI = 0.71–18.2, P = 0.59; AOR = 1.22, 95% CI = 0.57–2.61, P = 0.60) (Table 2). This evidence concerns the gene GSTM1 and chronic obstructive pulmonary disease.