Can rescaling dose of dialysis to body surface area in the HEMO study explain the different responses to dose in women versus men?
OBJECTIVE
In the Hemodialysis (HEMO) Study, the lower death rate in women but not in men assigned to the higher dose (Kt/V) could have resulted from use of "V" as the normalizing factor, since women have a lower anthropometric V per unit of surface area (V/SA) than men.


METHODS
The effect of Kt/V on mortality was re-examined after normalizing for surface area and expressing dose as surface area normalized standard Kt/V (SAn-stdKt/V).


RESULTS
Both men and women in the high-dose group received approximately 16% more dialysis (when expressed as SAn-stdKt/V) than the controls. SAn-stdKt/V clustered into three levels: 2.14/wk for conventional dose women, 2.44/wk for conventional dose men or 2.46/wk for high-dose women, and 2.80/wk for high-dose men. V/SA was associated with the effect of dose assignment on the risk of death; above 20 L/m(2), the mortality hazard ratio = 1.23 (0.99 to 1.53); below 20 L/m(2), hazard ratio = 0.78 (0.65 to 0.95), P = 0.002. Within gender, V/SA did not modify the effect of dose on mortality.


CONCLUSIONS
When normalized to body surface area rather than V, the dose of dialysis in women in the HEMO Study was substantially lower than in men. The lowest surface-area-normalized dose was received by women randomized to the conventional dose arm, possibly explaining the sex-specific response to dialysis dose. Results are consistent with the hypothesis that when dialysis dose is expressed as Kt/V, women, due to their lower V/SA ratio, require a higher amount than men.
Daugirdas
John T
JT
Division of Nephrology, Department of Medicine, University of Illinois at Chicago, Chicago, IL 60612-7323, USA. jtdaugir@uic.edu
Greene
Tom
T
Chertow
Glenn M
GM
Depner
Thomas A
TA
D001830:Body Surface Area; D005260:Female; D006801:Humans; D007700:Kinetics; D008297:Male; D008954:Models, Biological; D015337:Multicenter Studies as Topic; D016016:Proportional Hazards Models; D016032:Randomized Controlled Trials as Topic; D006435:Renal Dialysis / Q000401:mortality*; D012107:Research Design; D018570:Risk Assessment; D012307:Risk Factors; D012737:Sex Factors; D014508:Urea / Q000378:metabolism
D014508:Urea