Table 4. Comparison of performance of glomerular filtration rate equations before and after modification in the validation database.

Assessment index	MDRD	CKD-EPI	MacIsaac
Mean difference (ml/min)
Before	7.42	2.38	−3.10
After	−4.84	2.17	−5.30
Slope
Before	0.42	0.22	0.25
After	0.14	0.15	0.11
Intercept (ml/min)
Before	−26.70	−14.26	−20.59
After	−14.11	−8.91	−12.53
Relationship
Before	0.784	0.846	0.777
After	0.804	0.851	0.810
P10 (%)
Before	30.7%	32.3%	36.1%
After	35.7%	38.4%*	37.3%
P30 (%)
Before	75.7%	79.4%	82.4%
After	84.1%**	84.5%*	85.3%
Root mean square error
Before	0.321	0.256	0.233
After	0.227	0.227	0.225
Total deviation index 70%
Before	26.325	17.660	20.021
After	16.981	15.458	16.520
Total deviation index 75%
Before	30.974	20.778	23.557
After	19.980	18.187	19.438
Total deviation index 80%
Before	32.551	21.837	24.756
After	20.997	20.428	19.113

MDRD: modification of diet in renal disease; CKD-EPI: Chronic Kidney Disease Epidemiology Collaboration; Relationship: correlated coefficient of estimated GFR (eGFR) with reference GFR (rGFR); P₁₀: proportion of eGFR that were within 10% of rGFR; P₃₀: proportion of eGFR that were within 30% of rGFR.

^* P<0.05,

^** P<0.01, compared with the original equation.