TABLE 3.

Estimates of causal effect size for body mass index (BMI) and lung function traits (forced expiratory volume in 1 s (FEV₁), forced vital capacity (FVC) and FEV₁/FVC)

Population	Trait 1	Trait 2	Direction	Causal effect size#	se	p-value	nSNP
East Asian	BMI	FEV1	→	−0.0773	0.021	2.46×10−4	68
			←	0.0884	0.033	6.53×10−3	17
		FVC	→	−0.1084	0.021	3.44×10−7	67
			←¶				6
		FEV1/FVC	→	0.0332	0.021	0.115732	69
			←¶				3
European	BMI	FEV1	→	−0.1057	0.012	4.65×10−18	50
			←	0.0250	0.012	0.0308	411
		FVC	→	−0.1564	0.012	1.23×10−37	50
			←	−0.0180	0.013	0.154475	379
		FEV1/FVC	→	0.1622	0.014	8.01×10−33	48
			←	0.0393	0.009	4.75×10−6	599

n_SNP: number of single nucleotide polymorphisms in the instrumental variable; →: trait 1→trait 2 causal direction; ←: trait 2→trait 1 causal direction. ^#: causal effect sizes are in units of per standard deviation increase in exposure; ^¶: the FVC and FEV₁/FVC genome-wide association studies do not have enough SNPs at the genome-wide significance level to construct the instrument variable.