Table 3.

Cohen's κ table, comparison of classification of patients in stages of CKD according to measured and estimated GFR by the formulas

Estimated GFR	Measured GFR (ml/min per 1.73 m2)
	≥90	60 to 89	30 to 59	15 to 29	Total
Cockcroft-Gault (ml/min per 1.73 m2; Cohen's κ = 0.47)
≥90	70	33	6	0	109
60 to 89	12	50	24	0	86
30 to 59	0	10	39	16	65
15 to 29	0	0	0	11	11
MDRD (ml/min per 1.73 m2; Cohen's κ = 0.51)
≥90	53	13	7	0	73
60 to 89	28	59	12	0	99
30 to 59	1	21	47	10	79
15 to 29	0	0	3	17	20
CKD-EPI (ml/min per 1.73 m2; Cohen's κ = 0.56)
≥90	73	30	6	0	109
60 to 89	9	50	17	0	76
30 to 59	0	13	45	9	67
15 to 29	0	0	1	18	19
Total	82	93	69	27	271

The bold numbers indicate the number of patients classified to the same CKD stage according to both compared methods.