Table 3.

GFR levels estimated by various cystatin C equations and correlation coefficients between the estimated GFR and measured GFR across different GFR categories (ml/min per 1.73 m2)

Whole Group (n = 240)GFR <60 (n = 31)GFR <90 (n = 74)GFR 90 to 134 (n = 84)GFR ≥ 135 (n = 81)GFR ≥ 150 (n = 41)
Mean; median
    measured GFR109.7; 11237.26; 3759.14; 66111.4; 110.5153.9; 150166.6; 162
    equations with serum cystatin C
        Bökenkamp et al.140.5; 143.152.05; 5181.49; 87.9153.6; 145.6180.6; 169.9191; 179.3
        Filler and Lepage110.6 to 111.845.18; 4466.23; 70.4120.1; 113.7141.2; 132.5149.5; 139.9
        Grubb et al.148.4; 141.440.56; 36.968.09; 70.5163.2; 150.9206.6; 189.2227.9; 202.1
        Zapitelli-CysEq93.92; 93.7537.29; 35.456.35; 58.5102.4; 96.0119.3; 111.5126.7; 118
    equations with serum cystatin C and serum creatinine
        Bouvet et al.108.5; 107.151.85; 51.370.72; 76.45106.6; 106.5144.9; 137.7160.2; 152.9
        CKiD89.58; 91.141.83; 41.357.82; 61.497.03; 94.19110.9; 109.6116.8; 112.3
        Zapitelli-CysCrEq92.25; 94.6536.43; 34.654.19; 58100.8; 96.0118.2; 115.6125.6; 120
Correlation coefficient (95% CI)
    equations with serum cystatin C
        Bökenkamp et al.0.82 (0.78 to 0.86)0.88 (0.76 to 0.94)0.84 (0.76 to 0.90)0.36 (0.16 to 0.54)0.42 (0.22 to 0.59)0.43 (0.14 to 0.66)
        Filler and Lepage0.82 (0.78 to 0.86)0.88 (0.76 to 0.94)0.84 (0.76 to 0.90)0.45 (0.25 to 0.61)0.42 (0.22 to 0.59)0.43 (0.14 to 0.66)
        Grubb et al.0.80 (0.74 to 0.84)0.84 (0.69 to 0.92)0.77 (0.66 to 0.85)0.31 (0.11 to 0.49)0.36 (0.15 to 0.54)0.34 (0.02 to 0.59)
        Zapitelli-CysEq0.81 (0.76 to 0.85)0.87 (0.75 to 0.94)0.83 (0.74 to 0.89)0.40 (0.20 to 0.56)0.42 (0.22 to 0.59)0.43 (0.14 to 0.66)
    equations with serum cystatin C and serum creatinine
        Bouvet et al.0.99 (0.99 to 0.99)0.99 (0.99 to 0.99)0.99 (0.99 to 0.99)0.99 (0.99 to 0.99)0.99 (0.99 to 0.99)0.99 (0.99 to 0.99)
        CKiD0.81 (0.76 to 0.85)0.92 (0.84 to 0.96)0.82 (0.72 to 0.88)0.40 (0.21 to 0.57)0.29 (0.07 to 0.48)0.30 (−0.01 to 0.56)
        Zapitelli-CysCrEq0.82 (0.78 to 0.86)0.91 (0.82 to 0.95)0.84 (0.75 to 0.89)0.39 (0.19 to 0.56)0.36 (0.15 to 0.54)0.39 (0.09 to 0.63)
  • CI, confidence interval.