DOQI becomes K/DOQI

Publication of the Dialysis Outcomes Quality Initiative (DOQI) Clinical Practice Guidelines by the US National Kidney Foundation (NKF) in 1997 provided much needed direction for healthcare professionals caring for patients on dialysis.

These guidelines were based on critical appraisal of the evidence available at the time and have recently been expanded and updated.(1,2) Supported by an unrestricted educational grant from Amgen, the DOQI guidelines have been translated into over 10 languages and used as a basis for clinical performance measures across the world. During the development of these guidelines it was recognised that efforts to further improve outcomes for patients on dialysis needed a pre-emptive approach with management also being directed towards individuals with earlier stages of kidney disease who were at risk of progressing to "end-stage" kidney failure.

Thus, in 1999, the NKF launched the Kidney Disease Outcomes Quality Initiative (K/DOQI) with the remit of developing evidence-based guidelines for a broader range of patients including those with kidney disease not requiring dialysis and with conditions that may lead to kidney damage. The first set of Clinical Practice Guidelines to result from this initiative covering the classification, evaluation and stratification of chronic kidney disease has just been published in a supplement to the American Journal of Kidney Disease.(3) This document includes a summary of the background information available to the work group, 15 guidelines with accompanying rationale, suggestions for performance measures or "standards", and describes the methods used to review the evidence.

Other guidelines under development will be focused on therapy and will cover the management of bone disease, dyslipidaemia and blood pressure in all patients with chronic kidney disease, including those on dialysis or with a functioning kidney transplant. Future topics are expected to include cardiovascular disease in dialysis patients and kidney biopsy [www.kdoqi.org].

The problem of under-diagnosed chronic kidney disease

Chronic kidney disease is a major public health problem, but is under-diagnosed and under-treated across the world. For example, a recent US population survey has estimated that 7.6% of Americans have a reduced glomerular filtration rate.(4) Most of these patients are symptom-free, at least in the early stages of their disease and only come to medical attention as a result of routine blood testing or analysis of urine.

Even then, clinicians often underestimate the severity of kidney failure, thereby depriving patients of effective therapies that may slow progression of kidney damage, correct complications of uraemia and reduce the associated risk of cardiovascular disease. This is not helped by the lack of a universally agreed classification of chronic kidney disease, nor of any clear guidance as to when to screen for and treat the various complications that may be present. As a result, many patients are poorly managed and present to a nephrologist only when they need to start dialysis.

The new guidelines

This first set of the new K/DOQI Clinical Practice Guidelines will help to highlight the problem of undetected kidney disease. The guidelines have been compiled by a team of experts including nephrologists, epidemiologists, laboratory physicians, dietitians, social workers, elderly-care physicians and family practitioners. A subgroup of the committee included paediatric nephrologists and examined issues specifically related to children.

The work group set out to provide, for the first time, a classification system for staging chronic kidney disease and evaluated the best methods of assessing it. They also examined the association between the level of kidney function and the development of complications and attempted to stratify the risk of loss of kidney function with that of developing cardiovascular disease. Their recommendations are based on an exhaustive review of the literature and the guidelines are graded according to the quality of the supporting evidence. Where this is lacking, specific recommendations for areas of future research are provided. The document is intended for use by patients, their families, health care professionals, diagnostic laboratories, organisations providing, purchasing or planning health care and researchers.

Terminology revamped

To help raise the profile of the problem of undiagnosed kidney failure, the group chose to abandon the term "renal", which may require interpretation and explanation to the lay public, and have substituted the word "kidney", which is readily understood. "Chronic kidney disease" is used to describe conditions in which there is kidney damage and includes patients with a normal, elevated or decreased glomerular filtration rate (GFR). Five stages of chronic kidney disease are recognised ranging from stage 1 (normal or increased GFR) through to stage 5 (GFR<15ml/min/1.73m² or requiring dialysis) (table 1). The term "end-stage kidney failure" has been retained to describe those individuals treated by dialysis or kidney transplantation. Each stage of kidney disease has been linked to an action plan to focus attention on the management priorities. For example, patients should be evaluated and treated for uraemic complications such as anaemia when they reach stage 3 chronic kidney disease (GFR 30-59ml/min/1.73m²).

Stage	Description	GFR (ml/min/1.73 m2)	Action Plan
	At increased risk	90 (with CKD risk factors)	Screening CKD risk reduction
1	Kidney damage with normal or GFR	90	Diagnosis and treatment Treatment of comorbid conditions Slowing progression CVD risk reduction
2	Kidney damage with mild GFR	60-89	Estimating progression
3	Moderate GFR	30-59	Evaluating and treating complications
4	Severe GFR	15-29	Preparation for kidney replacement therapy
5	Kidney failure	<15 (or dialysis)	Replacement (if uraemia present)

Table 1: Patients who are at increased risk of developing chronic kidney disease are shown in the unshaded area. Chronic kidney disease (CKD - shaded area) is defined as either kidney damage or GFR <60 ml/min/1.73m² for 3 months. Kidney damage is defined as pathological abnormalities or markers of damage including abnormalities of blood, urine tests or imaging studies. CVD = Cardiovascular disease.

An end to 24 hour urine collections?

One aspect of the guidelines that is likely to be controversial is the recommendation to estimate kidney function on the basis of GFR calculated from serum creatinine concentration using a prediction equation which corrects for other factors such as age, gender and body size. Coupled with the recommendation that urinary protein excretion should be estimated on an untimed "spot" urine sample using the albumin-to-creatinine ratio, the working group has effectively abandoned the need for 24-hour urine collection in the majority of patients. They argue that, based on the available evidence, measurement of creatinine clearance using timed samples (eg, 24 hours) does not improve the estimation of GFR over that provided by the use of the equations. Furthermore, proteinuria in glomerular disease in primarily due to increased urinary albumin excretion, which is readily measurable by albumin-specific Dipstix or the ratio of albumin to creatinine in a spot sample. The limitations of this approach are acknowledged but the working group argue that the exact level of proteinuria is not usually needed for clinical decision making and that "a rough estimation of the level and changes over time is sufficient". Such an approach may constitute a welcome change for patients and laboratory staff, both of whom have to handle the urine samples, but may be unacceptable to some nephrologists.

The likely impact of K/DOQI

Judging by the success of the earlier DOQI project, it is likely that the new K/DOQI guidelines will have a major impact on the management of patients with chronic kidney disease, both in and beyond the USA. Most importantly, this new document is likely to focus attention on kidney disease as a worldwide health problem. Assuming that this leads to improved outcomes for such individuals, the main objective of the K/DOQI project will have been fulfilled.