Table 2.

Distribution of eGFR and cystatin C according to various estimating equations

eGFR category (mL/min per 1.73 m2)	Cystatin C distribution (mg/L)
	Number	%	Mean	Standard deviation	Lower quartile	Median	Upper quartile	No. (%) with cystatin C >1.23 mg/L
MDRD equation
<40	121	2.6%	1.9	0.7	1.5	1.8	2.3	107 (88.4%)
40–49	229	4.9%	1.3	0.3	1.1	1.3	1.5	125 (54.6%)
50–59	447	9.7%	1.0	0.3	0.9	1.1	1.2	108 (24.2%)
60–69	836	18.1%	0.9	0.2	0.8	0.9	1.1	65 (7.8%)
70–79	1112	24.0%	0.9	0.2	0.8	0.9	1.0	26 (2.3%)
≥80	1883	40.7%	0.8	0.1	0.7	0.8	0.9	13 (0.7%)
Cockcroft–Gault equation
<40	142	3.1%	1.8	0.7	1.4	1.7	2.1	120 (84.5%)
40–49	196	4.2%	1.3	0.3	1.1	1.2	1.5	99 (50.5%)
50–59	427	9.2%	1.1	0.3	0.9	1.1	1.2	101 (23.7%)
60–69	627	13.5%	1.0	0.2	0.9	1.0	1.1	70 (11.2%)
70–79	738	15.9%	0.9	0.2	0.8	0.9	1.0	29 (3.9%)
≥80	2498	54.0%	0.8	0.1	0.7	0.8	0.9	25 (1.0%)
Mayo equation
<40	64	1.4%	2.3	0.8	1.8	2.1	2.5	61 (95.3%)
40–49	56	1.2%	1.6	0.4	1.4	1.6	1.8	45 (80.4%)
50–59	102	2.2%	1.3	0.3	1.2	1.3	1.5	64 (62.8%)
60–69	193	4.2%	1.3	0.3	1.1	1.2	1.4	93 (48.2%)
70–79	322	7.0%	1.1	0.3	0.9	1.1	1.2	76 (23.6%)
≥80	3891	84.0%	0.9	0.2	0.7	0.8	1.0	105 (2.7%)
Cystatin C equationa
<40	145	3.1%	2.1	0.6	1.7	1.9	2.2	145 (100%)
40–49	188	4.1%	1.4	0.09	1.3	1.4	1.5	188 (100%)
50–59	320	6.9%	1.2	0.07	1.1	1.2	1.3	111 (4.7%)
60–69	553	11.9%	1.1	0.06	1.0	1.0	1.1	0 (0%)
70–79	738	15.9%	1.0	0.05	0.9	0.9	1.0	0 (0%)
≥80	2684	58.0%	0.8	0.09	0.7	0.8	0.8	0 (0%)
Combined cystatin C and creatinine equationa
<40	114	2.5%	2.2	0.6	1.8	2.0	2.4	114 (100%)
40–49	164	3.5%	1.4	0.2	1.3	1.5	1.6	143 (87.2%)
50–59	284	6.1%	1.2	0.1	1.1	1.2	1.3	134 (47.2%)
60–69	545	11.8%	1.1	0.1	1.0	1.1	1.1	46 (8.4%)
70–79	805	17.4%	0.9	0.1	0.9	1.0	1.1	6 (0.8%)
≥80	2716	58.7%	0.8	0.1	0.7	0.8	0.9	1 (0.04%)

Note:

^aEquations 2 and 3 in Table 4 of Stevens et al. ¹⁸

Abbreviations: eGFR, estimated glomerular filtration rate; MDRD, modification of diet in renal disease.