Rationale for Guideline Kt/V urea Targets for Hemodialysis

Hemodialysis Adequacy (Kt/V) Targets

Kt/V urea for hemodialysis

Contribution from the Canadian Society of Nephrology Clinical Practice Guidelines Committee

Source: CSN Guidelines Statement extracted from HD CPGs 2006 edition (J Am Soc Nephrol 17: S1-27, 2006):

Guideline: The minimum acceptable target for urea clearance during hemodialysis is a single-pool Kt/V of 1.2 or percent reduction of urea (PRU) of 65% three times per week.

Rationale: The National Cooperative Dialysis Study (NCDS) established that higher dialysis dose resulted in reduced morbidity (1), although the intensity of dialysis in both treatment groups was considerably lower than in current practice. More recently, observational studies have suggested that urea clearance below a single-pool Kt/V of 1.2 or PRU of 65% three times per week is associated with increased mortality (2– 6). Although observational data from patients treated with thrice-weekly and quotidian hemodialysis suggest that even higher levels of urea clearance are associated with better clinical outcomes (7–12), a well-designed, randomized study found no benefit of a single pool Kt/V target of 1.65 compared with 1.25 (13). Although this study cannot exclude a mortality benefit < 25%, there is no evidence to support increasing the target Kt/V above currently recommended levels. Since no grade A evidence (apart from the NCDS) indicates that increasing hemodialysis dose will reduce morbidity or mortality, it is possible that reducing the target Kt/V to levels <1.2 might not compromise clinical outcomes. However, in the absence of an adequately powered randomized study to confirm this hypothesis, the Committee continues to recommend a target single-pool Kt/V of > 1.2.

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