Table 1 Characteristics of studies included in the meta-analysis.
| Study and reference | Ethnicity/Country | Age | COPD definition | Smoking history | Methodology of genotyping |
|---|---|---|---|---|---|
| Bergen cohort from Pillai et al [26] | NR/Norway | NR | post-bronchodilator FEV1<80% predicted and FEV1/FVC<0.7 | a minimum smoking history of 2.5 pack-years | Illumina's HumanHap550 BeadChip |
| Copenhagen City Heart Study from Kaur-Knudsen et al [25] | NR/Denmark | NR | ICD-8 491-492 ICD-10 J41-J44 | NR | TaqMan method |
| COPDGene study from Kim et al [24] | non-Hispanic white subjects/America | 45-80 | post-bronchodilator FEV1<80% predicted and FEV1/FVC<0.7 | a minimum smoking history of 10 pack-years | TaqMan method |
| COPACETIC cohort from Lambrechts et al [23] | NR/the Netherlands | 50-75 | pre-bronchodilator FEV1/FVC<0.7 | a minimum smoking history of 20 pack-years | Illumina's HumanHap610-Quad BeadChip |
| LEUVEN cohort from Lambrechts et al [25] | NR/Belgium | >50 | post-bronchodilator FEV1/FVC<0.7 | a minimum smoking history of 15 pack-years | iPLEX™ genotyping assay |
| NETT/NAS cohorts from Pillai et al [26] | non-Hispanic white subjects/America | NR | FEV1 ≤45% predicted and bilateral emphysema on chest CT |
cases: former smokers controls: a minimum smoking history of 10 pack-years | Sequenom iPLEX or TaqMan method |
| New Zealand study from Young et al [27] | Caucasian/New Zealand | Case: >40; Controls:45-80 | post-bronchodilator FEV1<80% predicted and FEV1/FVC<0.7 | a minimum smoking history of 15 pack-years | iPLEX™ genotyping assay |