Table 1—

Results of predictive equations in the entire diabetic population (n = 124) divided into formulae related to creatinine and cystatin

Creatinine-based formula
CGMDRDrMDRDMCQArnal-DadeMacIsaacTanRule
Mean ± SD (ml/min per 1.73 m2)63.3 ± 37.751.4 ± 24.348.3 ± 22.960.9 ± 32.255.7 ± 34.766.1 ± 32.963.8 ± 33.152.4 ± 31.6
Range16–20810–12310–11610–1536–19511–1729–1707–166
Correlation coefficient with iGFR0.790.870.870.870.760.820.820.81
Difference with iGFR (nonparametric)<0.001<0.05<0.001<0.001NS<0.001<0.001<0.01
Median absolute percent difference with iGFR45.2 ± 52.027.7 ± 24.626.2 ± 21.731.9 ± 34.431.2 ± 33.042.9 ± 45.438.3 ± 41.027.1 ± 27.4
Bland-Altman
    r+0.10−0.62−0.68−0.18−0.02−0.12−0.11−0.18
    PNS<0.001<0.001<0.05NSNSNS<0.05
    2 SD69.036.437.434.847.840.640.641.4
Accuracy (%)
    Within ± 152933363431323039
    Within ± 305068646264555967
    Within ± 507289898287727789
AUC*
iGFR <60 ml/min per 1.73 m2 (n = 76)0.870.940.940.940.950.960.960.96
    Sensitivity88.285.585.581.690.892.192.192.1
    Specificity68.787.587.591.789.687.587.587.5
    Criterion≤67.2≤53.4≤58.3≤62.3≤61.9≤71.8≤69.5≤55.7
AUC
iGFR <30 ml/min per 1.73 m2 (n = 36)0.890.970.970.950.930.940.940.94
    Sensitivity75.094.494.488.988.980.680.680.6
    Specificity9292929285.294.394.394.3
    Criterion≤38.3≤41.8≤39.3≤45.1≤35.4≤42.4≤40.0≤29.5
  • For the Bland-Altman comparison, r and P represent the correlation and its specificity between [average (tested equation + iGFR)] and (tested equation − iGFR). iGFR = 56.1 ± 35.3 ml/min per 1.73 m2 (range 8–164).

  • * For the ROC curves for the estimated equations, AUC = area under the ROC curves.

  • P < 0.05 vs. other areas under the curve. CG, Cockroft-Gault.