LD score regression was used to assess the extent of confounding. Absence of significant confounding indicates that factors such as sample overlap and/or population stratification are not evident. Pre-computed LD scores from a European population were used (see URLs), based on genotypes for 1,293,150 HapMap3 SNPs in samples from the 1000 Genomes Project EUR population. Association results were filtered (info > 0.9 and MAF > 1%) before running LD score regression on (i) 3 pairwise meta-analyses of results from UK BiLEVE (stage 1) and UK Biobank (stage 2), UK BiLEVE and SpiroMeta and UK Biobank and SpiroMeta; (ii) bivariate analyses of the 3 pairs of cohorts.
