GSTP1 and chronic obstructive pulmonary disease: Subgroup analysis based on ethnicity showed that in the homozygote model (OR = 2.064, PZ = 0.000) and recessive model (OR = 1.850, PZ = 0.000), GSTP1 rs1695 was significantly associated with COPD risk among Caucasians, while the association among Asians was not significant.