Table 3:

Performance of Estimating Equations in the External Validation Dataset

Equation Description				Performance
Group	Equation Number Year of Publication	Filtration markers	Demographics	Overall Population
				1-P30	RMSE
Equation with Creatinine only	1. Ref (2009)10	Creatinine	Age, sex, race	11.8 (10.5, 13.2)	0.199 (0.193, 0.206)
Equations with Cystatin C	2. Ref (2012)47	Cystatin C	Age, sex	17.4 1 (15.9, 18.88)	0.262 1 (0.250, 0.274)
	3. New (2020)	Cystatin C-B2M-BTP	Age, sex, race	14.8 2 (13.4, 16.2)	0.256 2 (0.243, 0.268)
	4. New/Recommended (2020)	Cystatin C-B2M-BTP	Age, sex	15.6 2 (14.2, 17.1)	0.259 2 (0.247, 0.271)
Equations with Creatinine and Cystatin C	5. Ref (2012)47	Creatinine -Cystatin C	Age, sex, race	9.4 1 (8.2, 10.6)	0.199 1 (0.191, 0.206)
	6. New (2020)	Creatinine - Cystatin C-B2M-BTP	Age, sex, race	8.4 5, 3 (7.3, 9.5)	0.195 5, 3 (0.187, 0.203)
	7. New/Recommended (2020)	Creatinine -Cystatin C-B2M-BTP	Age, sex	8.6 5,4 (7.5, 9.8)	0.197 5, 4 (0.188, 0.205)

1-P₃₀ and RMSE are measures of accuracy. 1-P₃₀ is computed as 100 percent minus the percent of estimates greater than 30% of the measured GFR; RMSE, root mean square error; B2M, Beta2-Microglobulin; BTP, Beta-Trace Protein; A, age; S, sex; R, race;

Reference equations are the 2009 CKD-EPI creatinine equation (1), 2012 CKD-EPI cystatin C equation (2), and 2012 CKD-EPI creatinine-cystatin C equation (3). The superscript number indicates the comparator equation, and formatting of the superscript informs direction of the comparison. No underline marking indicates that the equation is better than the comparator equation for a p-value ≤ 0.05; an underline marking indicates that the equation is worse than the comparator equation for p-value ≤ 0.05. Double underline indicates that the equation is neither better nor worse than the comparator equation P >0.05.