Table 5.

Adjusted estimates of group–level incidence rates of nephrolithiasis in South Carolina by race from 1997 to 2012: Model 4

Model 4: Race	5-yr Change in Kidney Stone Incidence (95% Confidence Interval)
White	1.03 (1.02 to 1.03)
Black	1.15 (1.14 to 1.17)
Other	1.43 (1.38 to 1.48)

Model 4 included an interaction term between race and year. All models with interactions additionally included each main effect, lower–order interaction terms, and a random intercept for county of residence. Models examining for race effects were adjusted for age and sex.