Unlike CHARGE, SpiroMeta used normalized residuals as phenotypes, adjusted for age2 rather than age, and did not adjust for smoking. For better comparison, SpiroMeta conducted modified analyses following the CHARGE analytic method described above in 16,178 participants from adult cohorts with complete quantitative smoking data available. Results from the CHARGE GWAS and SpiroMeta replication were combined in a joint meta-analysis using inverse variance weighting with METAL. SpiroMeta results with P<8.33×10−4, based on an overly conservative Bonferroni correction for 60 tests (30 SNPs tested for association with two traits, FEV1/FVC and FEV1), or joint meta-analysis results with P<5×10−8 (genome-wide significance threshold) were considered statistically significant.
