ArticlesWhen to initiate dialysis: effect of proposed US guidelines on survival
Introduction
There are no uniform objective criteria for the initiation of long-term dialysis therapy, despite major improvements in technology and advances in knowledge. Nephrologists initiate dialysis treatment in most cases on the basis of the observed evolution of uraemic symptoms and laboratory investigations, such as plasma creatinine concentration and creatinine clearance.1 However, the evolution of uraemic symptoms varies from patient to patient,2 so there is substantial variation in timing of dialysis initiation.3, 4, 5
In an attempt to improve the quality and outcome of dialysis care, the US National Kidney Foundation Dialysis Outcomes Quality Initiative was established.6 Multidisciplinary work groups developed recommendations for optimum clinical practice, with the intention of establishing evidence-based guidelines. However, no pertinent information was available on many issues. For others, the available evidence was flawed or weak. Consequently, the work groups had to formulate many of their recommendations on the basis of opinions.
In 1997, the peritoneal-dialysis work group published an opinion-based guideline on the initiation of long-term dialysis therapy.7 This guideline was based mainly on urea clearance (renal Kt/Vurea) and estimated protein intake, calculated from the urea excretion in the urine normalised protein equivalent of nitrogen appearance [nPNA]). Intakes of protein and energy decrease with deteriorating renal function, leading to changes in nutritional status. The work group advised that dialysis should start when renal Kt/Vurea had fallen to 2·0 per week. This value equals a creatinine clearance of about 14 mL/min. A lower Kt/Vurea would be acceptable only when nPNA was at least 0·8 g/kg daily.
Several studies from the USA4, 8 and Europe5, 9 reported lower renal Kt/Vurea or creatinine clearance at the start of dialysis in many patients. Implementation of the new guideline would therefore lead to earlier initiation of dialysis treatment in similar cases. It would have a major impact on the daily life of patients, exposing them at an earlier stage to the risks and inconvenience of dialysis. Earlier initiation would also necessitate an increase in dialysis staff and probably in dialysis units also, inevitably leading to an increase in costs.
Before implementation, the advantage of timely initiation has to be weighed against the negative effects.10 We explored empirical support for the Dialysis Outcomes Quality Initiative DOQI) recommendation by looking at the association between timing of dialysis initiation and differences in survival in a prospective study of new dialysis patients in the Netherlands.
Section snippets
Patients
All patients with new end-stage renal disease at 29 Dutch dialysis units were invited to take part in the Netherlands Cooperative Study on the Adequacy of Dialysis NECOSAD), a large multicentre prospective study. The study aims to monitor the quality and adequacy of dialysis treatment in the Netherlands. Eligibility criteria were age 18 years or older, availability of data on residual renal function 0–4 weeks before the start of chronic dialysis treatment, and no previous renal replacement
Results
318 patients met the inclusion criteria. We excluded 14 patients because of inaccurate urine collections, 20 with malignant disease, and 31 who had not received predialysis care.
Of the 253 patients available for the analysis, 94 (37%) had started dialysis late according to the DOQI guideline. As a consequence of the study definitions, mean initial renal function and estimated protein intake were significantly higher in timely than in late starters (table 1). The mean renal Kt/Vurea of the
Discussion
In this prospective cohort study better residual renal function at the start of dialysis was associated with better survival. We found a small beneficial effect of the DOQI guideline for the optimum time to initiate dialysis; we observed a gain in survival time of 2·5 months in the first 3 years after the start of dialysis. However, this gain could be an overestimation of the real benefit caused by lead-time. We do not know the rate of renal loss before the start of dialysis in our patients, so
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