K/DOQI clinical practice guidelines for chronic kidney disease: Evaluation, classification, and stratification

Introduction: Chronic as a public health problem. Chronic is a worldwide public health problem. In United States, there is a rising incidence and prevalence of failure, with poor outcomes and high cost. There is an even higher prevalence of earlier stages of disease. Increasing evidence, accrued in past decades, indicates that adverse outcomes of disease, such as failure, cardiovascular disease, and premature death, can be prevented or delayed. Earlier stages of can be detected through laboratory testing. Treatment of earlier stages of is effective in slowing progression toward failure. Initiation of treatment for cardiovascular risk factors at earlier stages of should be effective in reducing cardiovascular events both before and after onset of failure. Unfortunately, is under-diagnosed and under-treated in United States, resulting in lost opportunities for prevention. One reason is lack of agreement on a definition and classification of stages in progression of disease. A clinically applicable classification would be based on laboratory evaluation of severity of disease, association of level of function with complications, and stratification of risks for loss of function and development of cardiovascular disease. Charge to K/DOQI work group on disease. In 2000, National Kidney Foundation (NKF) Kidney Outcome Quality Initiative (K/DOQI) Advisory Board approved development of clinical practice guidelines to define and to classify stages in progression of disease. The Work Group charged with developing guidelines consisted of experts in pediatric epidemiology, laboratory medicine, nutrition, social work, gerontology, and family medicine. An Evidence Review Team, consisting of nephrologists and methodologists, was responsible for assembling evidence. Defining and classifying stages of severity would provide a common language for communication among providers, patients and their families, investigators, and policy-makers and a framework for developing a public health approach to affect care and improve outcomes of disease. A uniform terminology would permit: 1. More reliable estimates of prevalence of earlier stages of and of population at increased risk for development of 2. Recommendations for laboratory testing to detect earlier stages and progression to later stages 3. Associations of stages with clinical manifestations of 4. Evaluation of factors associated with a high risk of progression from one stage to next or of development of other adverse outcomes 5. Evaluation of treatments to slow progression or prevent other adverse outcomes. Clinical practice guidelines, clinical performance measures, and continuous quality improvement efforts could then be directed to stages of disease. The Work Group did not specifically address evaluation and treatment for disease. However, this guideline contains brief reference to diagnosis and clinical interventions and can serve as a road map linking other clinical practice guidelines and pointing out where other guidelines need to be developed. Eventually, K/DOQI will include interventional guidelines. The first three of these, on bone disease, dyslipidemia, and blood pressure management are currently under development. Other guidelines on cardiovascular in dialysis patients and biopsy will be initiated in Winter of 2001. This report contains a summary of background information available at time Work Group began its deliberations, 15 guidelines and accompanying rationale, suggestions for clinical performance measures, a clinical approach to using these guidelines, and appendices to describe methods for review of evidence. The guidelines are based on a systematic review of literature and consensus of Work Group. The guidelines have been reviewed by K/DOQI Advisory Board, a large number of professional organizations and societies, selected experts, and interested members of public and have been approved by Board of Directors of NKF. Framework. The Work Group defined chronic disease to include conditions that affect kidney, with potential to cause either progressive loss of function or complications resulting from decreased function. Chronic was thus defined as presence of damage or decreased level of function for three months or more, irrespective of diagnosis. The target population includes individuals with or at increased risk of developing disease. The majority of topics focus on adults (age ≥18 years). Many of same principles apply to children as well. In particular, classification of stages of and principles of diagnostic testing are similar. A subcommittee of Work Group examined issues related to children and participated in development of first six guidelines of present document. However, there are sufficient differences between adults and children in association of with signs and symptoms of uremia and in stratification of risk for adverse outcomes that these latter issues are addressed only for adults. A separate set of guidelines for children will have to be developed by a later Work Group. The target audience includes a wide range of individuals: those who have or are at increased risk of developing (the target population) and their families; health care professionals caring for target population; manufacturers of instruments and diagnostic laboratories performing measurements of function; agencies and institutions planning, providing or paying for health care needs of target population; and investigators studying disease. There will be only brief reference to clinical interventions, sufficient to provide a basis for other clinical practice guidelines relevant to evaluation and management of disease. Subsequent K/DOQI clinical practice guidelines will be based on framework developed here. Definition of disease. Why Kidney? The word kidney is of Middle English origin and is immediately understood by patients, their families, providers, health care professionals, and lay public of native English speakers. On other hand, renal and nephrology, derived from Latin and Greek roots, respectively, commonly require interpretation and explanation. The Work Group and NKF are committed to communicating in language that can be widely understood, hence preferential use of kidney throughout these guidelines. The term End-Stage Renal Disease (ESRD) has been retained because of its administrative usage in United States referring to patients treated by dialysis or transplantation, irrespective of their level of function. Why Develop a New Classification? Currently, there is no uniform classification of stages of disease. A review of textbooks and journal articles clearly demonstrates ambiguity and overlap in meaning of current terms. The Work Group concluded that uniform definitions of terms and stages would improve communication between patients and providers, enhance public education, and promote dissemination of research results. In addition, it was believed that uniform definitions would enhance conduct of clinical research. Why Base a New Classification System on Severity of Disease? Adverse outcomes of are based on level of function and risk of loss of function in future. Chronic tends to worsen over time. Therefore, risk of adverse outcomes increases over time with severity. Many disciplines in medicine, including related specialties of hypertension, cardiovascular disease, diabetes, and transplantation, have adopted classification systems based on severity to guide clinical interventions, research, and professional and public education. Such a model is essential for any public health approach to disease. Why Classify Severity as Level of GFR? The level of glomerular filtration rate (GFR) is widely accepted as best overall measure of function in health and disease. Providers and patients are familiar with concept that the is like a filter. is best measure of kidneys' ability to filter blood. In addition, expressing level of function on a continuous scale allows development of patient and public education programs that encourage individuals to Know your number! The term GFR is not intuitively evident to anyone. Rather, it is a learned term, which allows ultimate expression of complex functions of in one single numerical expression. Conversely, numbers are an intuitive concept and easily understandable by everyone.