Rationale for Guideline Kt/V urea Targets for Hemodialysis

Hemodialysis Adequacy (Kt/V) Targets

Contribution from the Caring for Australians with Renal Impairment (CARI) Guidelines Committee

The 2005 CARI Dialysis Adequacy Guideline includes the “Clinical Suggestion”:

• The minimum acheived spKt/V should be 1.2 (URR = 65%)

Rationale: The major difference of CARI compared to other guidelines, in the setting of “Dose of Dialysis in HD” relates to the lack of a formal guideline with, instead, a suggestion for clinical practice. As CARI has strict Australian National Health and Research Council criteria for the development of guidelines, we felt unable to produce a guideline for this topic that was based on level I or II evidence. There are only 2 significant RCTs assessing dose of dialysis – the NCDS study and the HEMO study. Given that the NCDS study examined time averaged concentration of urea and not Kt/V (which was a later mathematical construct derived from data from the trial), and that it examined an equivalent Kt/V of 0.8 – 1.0 it is not directly applicable to setting a target Kt/V of around 1.2 (as exists in other guidelines). Similarly, the HEMO study addressed the difference in outcome comparing Kt/V values of 1.2 vs 1.6 but doesn’t therefore truly address whether 1.2 is adequate and an appropriate target.

We felt it appropriate to recommend a Kt/V of 1.2 as a suggestion for clinical practice based primarily on the weight of evidence from observational studies and other guidelines. It should also be pointed out that in Australia, Kt/V has not been wholeheartedly embraced and at best only URR is relatively widely used. Further, dialysis hours per week are relatively long especially compared to the USA, with virtually all patients on at least 4 hours 3 times per week coupled with a growing trend to increased hours with both i) a trend to 5 hours 3 times per week as the standard for satellite dialysis; and ii) a growing trend to even longer hours dialysis via nocturnal home HD.

Prepared on behalf of CARI by Peter Kerr, Convenor of CARI Dialysis Adequacy (HD) Guidelines Working Group