Figure 1.

Bland-Altman figures of the estimated and measured kidney function. Bland-Altman plots—the difference between the estimated and measured renal function—is plotted against the measured GFR; therefore, a positive difference suggests an overestimation by the formula, whereas a negative difference suggests an underestimation. The dashed lines represent the mean difference between estimated and measured GFR; the solid lines represent the lines of agreement, calculated as mean difference plus or minus two times the SD of this difference.