Table 2.

Interpretation of the fixed effects coefficients from a linear mixed effects model assessing associations of APOL1 genotype with eGFR measured repeated over time

Variablea	Coefficient Interpretation	Coefficient Estimate	Coefficient SEM	P Value
APOL1 high risk	Difference in average baseline eGFR (milliliters per minute per 1.73 m2) among African ancestry participants with APOL1 high-risk alleles compare with whites	−2.95	1.05	0.005
APOL1 low risk	Difference in average baseline eGFR (milliliters per minute per 1.73 m2) among African ancestry participants with APOL1 low-risk alleles compare with whites	−3.77	0.62	<0.001
Years	Average eGFR slope (milliliters per minute per 1.73 m2 per year) among whites	−0.74	−0.07	<0.001
Years × APOL1 high risk	Difference in average eGFR slope (milliliters per minute per 1.73 m2 per year) among African ancestry participants with APOL1 high-risk alleles and whites	−1.50	0.20	<0.001
Years × APOL1 low risk	Difference in average eGFR slope (milliliters per minute per 1.73 m2 per year) among African ancestry participants with APOL1 low-risk alleles and whites	−0.58	0.11	<0.001

Results are the estimated fixed effects from a random slope model fit for the Chronic Renal Insufficiency Cohort Study example in model 2.

^aModel 2: APOL1 is the exposure variable of the genotype in conjunction with race with three categories (0, white; 1, APOL1 low risk; and 2, APOL1 high risk), with whites as the reference group. The random effects include both random intercept and random slope to account for subject-specific deviation from the population-average trajectory.