Table 7. Bias, Precision and Accuracy of 6-Variable MDRD and CKD-EPI Creatinine-Cystatin C Equations in 72 Subjects with Cirrhosis Stratified by Level of mGFR.

		6-Variable MDRD	CKD-EPI Creatinine-Cystatin C (2012)
mGFR ≥ 60 ml/min/1.73m2	Bias	−4.89	4.75
	P value†	0.0003
	Precision*	27.08	26.30
	P Value†	0.721
	Accuracy (I-P30)*	33.33	21.57
	P Value†	0.109
	Accuracy (I-P20)*	47.06	49.02
	P Value†	1.000
	Accuracy (RMSE)*	27.52	26.72
	P Value†	0.781
mGFR < 60 ml/min/1.73m2	Bias	−10.04	−5.11
	P value†	0.028
	Precision*	13.65	11.96
	P Value†	0.473
	Accuracy (I-P30)*	38.10	28.57
	P Value†	0.688
	Accuracy (I-P20)*	47.62	33.33
	P Value†	0.453
	Accuracy (RMSE)*	16.95	13.01
	P Value†	0.213

mGFR=GFR measured by non-radiolabeled iothalamate plasma clearance (gold standard)

eGFR=Estimated GFR

Difference score (DS)=mGFR-eGFR for each subject

Bias=Mean DS

Precision=Standard deviation of DS

Accuracy=Percentage of eGFRs that differed by greater than 30% (1-P₃₀) or 20% (1-P₂₀) of mGFRs or root mean square error (RMSE)

^*Lower values for precision and accuracy [(1-P₃₀), (1-P₂₀) and RMSE] indicate higher precision and accuracy for 6-variable MDRD and CKD-EPI creatinine-cystatin C equations

^†P values compare the performance of CKD-EPI creatinine-cystatin C (2012) to 6-variable MDRD equation. Note, the P-values for bias reflect difference in the location of bias, not the magnitude.