Can Rescaling Dose of Dialysis to Body Surface Area in the HEMO Study Explain the Different Responses to Dose in Women versus Men?

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. The effect of Kt/V on mortali...

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Bibliographic Details
Published in:Clinical journal of the American Society of Nephrology 2010-09, Vol.5 (9), p.1628-1636
Main Authors: Daugirdas, John T, Greene, Tom, Chertow, Glenn M, Depner, Thomas A
Format: Article
Language:English
Subjects:
Body Surface Area
Female
Humans
Kinetics
Male
Models, Biological
Multicenter Studies as Topic
Original
Proportional Hazards Models
Randomized Controlled Trials as Topic
Renal Dialysis - mortality
Research Design
Risk Assessment
Risk Factors
Sex Factors
Urea - metabolism
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Summary: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. 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). 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. 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.
ISSN:1555-9041
1555-905X
DOI:10.2215/CJN.02350310