Kt/V underestimates the hemodialysis dose in women and small men Elaine M. Spalding, Shahid M. Chandna, Andrew Davenport, Ken Farrington  Kidney International  Volume 74, Issue 3, Pages 348-355 (August 2008) DOI: 10.1038/ki.2008.185 Copyright © 2008 International Society of Nephrology Terms and Conditions

Figure 1 Relationship between Watson volume (V) and dry weight in 328 HD patients. The lines displayed represent best linear regression fit in men and women. HD, hemodialysis. Kidney International 2008 74, 348-355DOI: (10.1038/ki.2008.185) Copyright © 2008 International Society of Nephrology Terms and Conditions

Figure 2 Relationship between Wb and dry weight. Separate non-linear regression lines (of the form y=aWb) are shown for a=1, b=0.1–1.0, at increments of 0.1. For details see text. Bold lines represent the curves for b=0.67 and b=1. For clarity data points omitted. Kidney International 2008 74, 348-355DOI: (10.1038/ki.2008.185) Copyright © 2008 International Society of Nephrology Terms and Conditions

Figure 3 Relationship between Watson volume (V), body surface area, and W0.67 in 328 HD patients. Upper panel: relationship between Watson V and body surface area in 328 HD patients clustered into four groups—small women (<mean V for women), large women (>mean V for women), small men (<mean V for men), and large men (> mean V for men). *P<0.001 for comparison with all other groups. Lower panel: relationship between Watson V and W0.67 in 328 HD patients clustered into four groups—small women (<mean V for women), large women (>mean V for women), small men (<mean V for men), and large men (>mean V for men). *P<0.001 for comparison with all other groups. P<0.007 for comparison between small and large women. HD, hemodialysis. Kidney International 2008 74, 348-355DOI: (10.1038/ki.2008.185) Copyright © 2008 International Society of Nephrology Terms and Conditions

Figure 4 Histograms of distribution by gender of Kt (upper panel), Kt/BSA (middle panel), and Kt/W0.67 values (lower panel) equivalent to target Kt/V of 1.2 in 328 hemodialysis patients. Kidney International 2008 74, 348-355DOI: (10.1038/ki.2008.185) Copyright © 2008 International Society of Nephrology Terms and Conditions

Figure 5 Plots of estimates of ‘required’ Kt against Watson V. For definitions of ‘double reciprocal’ and ‘multiplicative,’ see reference Lowrie et al.20 and Materials and Methods section. Curves were fitted using the LOESS locally weighted regression technique. Continuous lines represent relationship in men. Broken lines represent relationship in women. Kidney International 2008 74, 348-355DOI: (10.1038/ki.2008.185) Copyright © 2008 International Society of Nephrology Terms and Conditions

Figure 6 Equivalent Kt/BSA and Kt/W0.67 for a range of prescribed Kt/V in 328 HD patients. Left panel: equivalent Kt/BSA for a range of prescribed Kt/V in 328 HD patients clustered into four groups—small women (<mean V for women), large women (>mean V for women), small men (<mean V for men), and large men (>mean V for men). Right panel: equivalent Kt/W0.67 for a range of prescribed Kt/V in 328 HD patients clustered into four groups—small women (<mean V for women), large women (>mean V for women), small men (<mean V for men), and large men (>mean V for men). BSA, body surface area; HD, hemodialysis. Kidney International 2008 74, 348-355DOI: (10.1038/ki.2008.185) Copyright © 2008 International Society of Nephrology Terms and Conditions

Figure 7 Kt/Wb equivalent to Kt/V=1.2 for a range of b between 0 and 1 in 328 HD patients. In the upper panel, mean values for female patients are shown relative to mean values in men. In the middle panel, mean values are shown in tertiles of V, relative to mean values in medium tertile. In the lower panel, mean values are shown in four groups (small women (<mean V for women), large women (>mean V for women), small men (<mean V for men), and large men (>mean V for men), relative to the values in large men). The dashed vertical lines in each panel represent the values of b, 0.5378 and 0.67, respectively. The former being the power of weight used in the Haycock formula for BSA, and the latter, an approximation to ‘metabolic size’.BSA, body surface area; HD, hemodialysis. Kidney International 2008 74, 348-355DOI: (10.1038/ki.2008.185) Copyright © 2008 International Society of Nephrology Terms and Conditions