Table 4. Longitudinal association between FEV₁ rate of decline, smoking and African ancestry, among African American participants in the Health ABC study.

	FEV1 (ml/yr)
	(N = 1,737)
Variable	Beta	SE	P value
Model 1 †
Intercept	1630.22	58.43	<0.001
African ancestry, %	−2.90	1.40	0.04
Age, year at time t	−26.45	10.18	0.01
Smoking, pack-years	−4.60	0.79	<0.001
Age*African*Pack-years	0.007	0.004	0.14
Model 2
Intercept	1629.17	58.66	<0.001
African ancestry, %	−4.37	1.70	0.01
Age, year at time t	−31.55	2.24	<0.001
Smoking, pack-years	−4.61	0.77	<0.001
Age*African*Former smoker	0.32	0.23	0.16
Age*African*Current smoker	0.12	0.43	0.78

Mixed effects models are adjusted for sex, standing height, household income, clinic site and two-way interactions among covariates. Age, height and African ancestry are mean centered.

^†Model 1 is also adjusted for smoking status.