Table 2.

Mean cystatin C concentrations by decade of age among participants with and without clinical risk factors for kidney disease

	Age (years)*
	<40 (n = 911)	40–49 (n = 1831)	50–59 (n = 2677)	60–69 (n = 4564)	70–79 (n = 7367)	80+ (n = 903)
	Cystatin C (mg/L) mean (SD)
Risk factors†	0.76 (0.21)	0.78 (0.16)	0.84 (0.17)	0.95 (0.28)	1.05 (0.34)	1.23 (0.38)
(n = 15 407)	(n = 584)	(n = 1369)	(n = 2135)	(n = 3950)	(n = 6556)	(n = 813)
No risk factors
All	0.72 (0.17)	0.75 (0.17)	0.79 (0.13)	0.85 (0.14)	0.96 (0.19)	1.06 (0.19)
(n = 2846)	(n = 327)	(n = 462)	(n = 542)	(n = 614)	(n = 811)	(n = 90)
Men‡	0.76 (0.21)	0.80 (0.17)	0.83 (0.11)	0.87 (0.13)	0.99 (0.20)	1.08 (0.17)
(n = 1049)	(n = 131)	(n = 210)	(n = 210)	(n = 197)	(n = 268)	(n = 33)
Women	0.69 (0.14)	0.70 (0.16)	0.76 (0.14)	0.84 (0.15)	0.94 (0.19)	1.05 (0.21)
(n = 1797)	(n = 196)	(n = 252)	(n = 332)	(n = 417)	(n = 543)	(n = 57)

^*P-value for trend across decades <0.001 for all groups.

^†P-value for age and risk factor interaction <0.001.

^‡P-value for age and sex interaction = 0.03.