Table 2.

Comparison of cystatin C, creatinine, eGFR, and CKD stage, NHANES 1988–1994 and 1999–2004 (n = 11,440)

Variables1988–19941999–2004Pa
Cystatin C, mg/L0.9 (< 0.1)0.9 (< 0.1)0.65
eGFRcystatin C, ml/min/1.73 m293.1 (0.8)94.6 (0.9)0.17
eGFRcystatin C (%)
    ≥ 9056.2 (1.7)58.7 (1.8)0.28
    60–8937.4 (1.4)34.3 (1.5)0.14
    45–594.3 (0.4)4.8 (0.5)0.48
    30–441.7 (0.2)1.5 (0.2)0.67
    < 300.4 (0.1)0.6 (0.1)0.12
CKD stage, eGFRcystatin C, ACR (%)
    normal84.9 (1.1)85.1 (0.9)0.87
    stage 13.9 (0.5)4.0 (0.5)0.88
    stage 24.7 (0.4)3.9 (0.4)0.11
    stage 3a4.3 (0.4)4.8 (0.5)0.43
    stage 3b1.7 (0.2)1.6 (0.2)0.72
    stage 4/50.4 (0.1)0.6 (0.1)0.11
Standard creatinine in 1988–1994 and 1999–2004
Creatinine, mg/dl0.8 (< 0.1)0.9 (< 0.1)< 0.001
eGFRcreatinine, ml/min/1.73 m293.2 (0.7)87.6 (0.7)< 0.001
eGFRcreatinine (%)
    ≥ 9053.2 (1.9)41.9 (1.7)< 0.001
    60–8941.1 (1.8)49.7 (1.5)< 0.001
    45–594.1 (0.3)6.1 (0.4)< 0.01
    30–441.2 (0.1)1.8 (0.2)0.01
    < 300.3 (< 0.1)0.5 (0.1)< 0.01
CKD stage, eGFRcreatinine, ACR (%)
    normal85.2 (1.0)83.6 (0.8)0.18
    stage 14.3 (0.6)3.9 (0.5)0.67
    stage 24.9 (0.4)3.9 (0.4)0.10
    stage 3a4.1 (0.3)6.2 (0.4)< 0.01
    stage 3b1.2 (0.1)1.8 (0.2)0.01
Standard creatinine in 1988–1994, minus 0.06 in 1999–2004b
Creatinine, mg/dl0.8 (< 0.1)0.8 (< 0.1)0.80
eGFRcreatinine, ml/min/1.73 m293.2 (0.7)95.9 (0.8)0.02
eGFRcreatinine (%)
    ≥ 9053.2 (1.9)55.1 (1.5)0.48
    60–8941.1 (1.8)38.9 (1.4)0.37
    45–594.1 (0.3)3.9 (0.3)0.69
    30–441.2 (0.1)1.5 (0.2)0.19
    < 300.3 (< 0.1)0.5 (0.1)0.02
CKD stage, eGFRcreatinine, ACR (%)
    normal85.2 (1.0)85.8 (0.8)0.63
    stage 14.3 (0.6)5.1 (0.6)0.29
    stage 24.9 (0.4)3.1 (0.4)< 0.01
    stage 3a4.1 (0.3)4.0 (0.3)0.77
    stage 3b1.2 (0.1)1.5 (0.2)0.16
ACR, mg/g5.8 (3.6–11.2)5.9 (3.9–11.0)0.19
ACR (%)
    < 3089.0 (0.9)89.7 (0.7)0.45
    30–2998.1 (0.8)8.6 (0.7)0.65
    ≥ 3003.0 (0.4)1.7 (0.2)0.01
  • ACR, urinary albumin-creatinine ratio; CKD, chronic kidney disease; eGFR, estimated glomerular filtration rate. CKD stages: stage 1, eGFR ≥ 90 ml/min/1.73 m2, ACR ≥ 30; stage 2, eGFR 60–89 ml/min/1.73 m2, ACR ≥ 30; stage 3a, eGFR 45–59 ml/min/1.73 m2; stage 3b, eGFR 30–44 ml/min/1.73 m2; stage 4 eGFR 15–30; stage 5 eGFR < 15 ml/min/1.73 m2.

  • a Comparing 1988–1994 and 1999–2004. The analysis was adjusted for the sampling weights used in the study design. The chi-square test (for categorical variables) and analysis of variance (for continuous variables) were used to compare the characteristics of 1988–1994 and 1999–2002 participants. Standard errors are shown in parentheses except for ACR, where median and interquartile range are shown. For kidney function outcomes, participants in each kidney function category were compared with all other participants. For example, for eGFRcystatin C, 45–59 ml/min/1.73 m2, participants with this characteristic were compared with participants with eGFRcystatin C ≥ 60 or <45 ml/min/1.73 m2.

  • b When reference populations (ages 20 to 39 yr without diabetes or hypertension) were compared, serum creatinine values were 0.06 mg higher in the 1999–2002 than the 1988–1994 population.