Rationale for Guideline for "Time of referral to Nephrologists"

Time of Referral to Nephrologists

Contribution from European Best Practice Guidelines Committee

The current 2002 version of the European Best Practice Guidelines recommend:

• Referral to nephrology should be considered when the GFR is <60 ml/min and is mandatory when the GFR is <30 ml/min.
• If a GFR prediction or measurement is not available, patients with chronic renal failure should be referred to a nephrologist when, on two consecutive measurements, plasma creatinine exceeds 150 μmol/l in men and 120 μmol/l in women, corresponding to a GFR of 50 ml/min. These patients should be referred whether or not there are other indications of chronic renal disease, such as proteinuria.

Rationale: Patients who start dialysis with no previous nephrology follow-up have a much higher mortality rate than those referred earlier1. Patients with chronic renal failure and a GFR < 30 ml/min generally progress and are likely to require dialysis. They need to be under the care of a nephrology service to prepare them for dialysis, pre-emptive transplant or conservative care if appropriate. This preparation includes selection of the most appropriate location and type of renal replacement therapy, creation of appropriate vascular or peritoneal access, vaccination against hepatitis B etc.. According to the NHANES III2 study 0.2% of the population fall into this category, and nephrology services need to be resourced to manage these patients.

Patients with GFR <60 ml/min may have complications similar to dialysis patients (e.g. renal anaemia, bone disease, fluid overload, hypertension etc.). Some of them may progress to require renal replacement therapy and this progression could be prevented or delayed by appropriate medical care (e.g. strict blood pressure control, ACE inhibition, treatment of the underlying condition etc.). It would be desirable for all of these patients to be seen by a nephrologist, at least to exclude a treatable primary renal cause. Approximately 5% of the population have GFR<60 and nephrology services will not be able to cope with this number of patients. In recognition of this practical limitation, the EBPG recommends referral when GFR is between 30-50 ml/min. Nephrologists need to shift their focus from treatment of renal failure to earlier intervention and prevention. Those patients with GFR < 60 ml/min who are not under nephrology care still need to be identified and the majority enrolled in a preventative programme supervised by internists and/or general practitioners.

At the time the guidelines were prepared, routine reporting of estimated GFR by the laboratory whenever serum creatinine was measured was not widespread in Europe (although the guidelines recommended this). Therefore, equivalent creatinine levels were provided, corresponding to a GFR of approximately 50 ml/min and validated in a large population3. When renal function is assessed by serum creatinine rather than GFR, there is a relatively higher threshold for mandatory referral to nephrology (equivalent to a GFR of 50 instead of 30 ml/min). This is to compensate for the fact that serum creatinine is a less reliable guide to renal function than estimated GFR.

References:

1. Jungers P, Zingraff J, Page B et al. Detrimental effects of late referral in patients with chronic renal failure: a case-control study. Kidney Int Suppl 1993; 41: S170–S173
2. Jones CA, McQuillan GM, Kusek JW et al. Serum creatinine levels in the US population: Third National Health and Nutrition Examination Survey. Am J Kidney Dis 1998; 32: 992–999
3. Couchoud C, Pozet N, Labeeuw M, Pouteil-Noble C. Screening early renal failure: cut-off values for serum creatinine as an indicator of renal impairment. Kidney Int 1999; 55: 1878–1884

Prepared on behalf of the European Best Practice Guidelines Committee by James Tattersall (Sub-group Chairman)