5.7.1. Introduction

Chronic kidney disease (CKD) is increasingly recognized as a major public health problem. CKD can be detected via simple biochemical tests including a creatinine-based estimate of the glomerular filtration rate (GFR) (Levey et al, 1999). CKD is now described based on internationally accepted definitions and diagnosed when structural or functional abnormalities of the kidneys persist for more than 3 months. The disease is categorized into 5 stages of increasing severity. Data derived from the National Health and Nutrition Examination Survey III (NHANES III) show that about 1 out 10 adult Americans exhibit CKD (Coresh et al, 2005 ). Estimates in Asia and Australia (Chen et al, 2005; Chadban et al, 2003) indicate the problem is of the same magnitude in those countries. In Europe several surveys have now been completed (Viktorsdottir et al., 2005; Otero et al., 2005; de Zeeuw D et al., 2005; Hallan et al. 2006a; Hallan et al. 2006b; Cirillo et al, 2006; Van Biesen et al, 2007); these studies indicate that CKD is of concern also in EU countries. CKD is a dangerous clinical condition for two reasons: first because renal impairment may prelude to the development of end stage renal disease (ESRD), i.e. the disease stage where dialysis and transplantation are needed, second because it amplifies the risk for cardiovascular complications. Independent from other risk factors, patients with stage 4-5 CKD have a death risk for cardiovascular complications which is 2-4 times higher than that of the coeval general population, whilst patients  with ESRD have a 100 times higher risk (Baigent et al, 2000). There is coherent, undisputable evidence that treatment can prevent or delay kidney disease progression and the resulting cardiovascular complications (Chobanian et al, 2003; National Kidney Foundation, 2002-2006; Sarnak et al., 2003; American Diabetes Association, 2006), but this knowledge has rarely been translated into public health policies. Moreover, early detection can prevent or delay progression to end stage renal disease (ESRD),

CKD was not listed among chronic diseases in the 2005 WHO report (World Health Organization, 2005; Yach et al, 2004). However, it is exceedingly frequent in patients with cardiovascular diseases where it acts as a risk multiplier (Sarnak et al. 2003). Furthermore, evidence is emerging that CKD is a risk factor for death and other clinical complications in other chronic diseases like in neoplasia and in chronic infections. Interpretative models are being developed to frame the link between CKD and other chronic diseases with the ultimate scope of devising policies aimed at improving clinical outcomes. Proteinuria and microalbuminuria (Boulware et al, 2003; Gansevoort et al, 2005) may be useful for the screening of CKD; indeed, studies are currently underway for further testing the value of these biomarkers at population level.

Figure 5.7.1. Development and progression of CKD.

ESRD and the resulting cost of renal replacement treatments are still in an expanding phase (Lysaght, 2002). Although the problem is well recognized, few countries have policies for CKD. The high prevalence of CKD, its contribution to cardiovascular risk and to other diseases and its economic implications are still largely overlooked by governments and health authorities and ignored by the population. In a context where costs for other chronic diseases such as hypertension, diabetes and cardiovascular diseases are magnified by the epidemics of obesity (Rodgers et al, 2004) and consume a large fraction of health care resources, full recognition of CKD as a preventable disease is an important issue. Indeed CKD prevention may also help to control the cardiovascular burden deriving from these diseases. Even though cardiovascular diseases largely remain the main contributor to the death toll of chronic diseases, communicable diseases are not yet under control in developed countries. CKD is very common in people with infectious diseases and neoplasias and amplifies the risk for adverse outcomes and the resulting costs in these conditions. For these reasons, health policies for CKD need to be harmonized with policies for other chronic diseases.

Information on CKD in the pre-ESRD phases in children is scarce. Available data indicate that CKD at this age is rare (Ardissino et al, 2003; Esbjorner et al, 1997). Data on renal replacement therapy (RRT) for ESRD in children are collected by the renal registries in Europe. Although rare, CKD and ESRD in children pose unique challenges because of the many extra-renal manifestations of renal insufficiency that affect growth as well as development.

Economic Impact of CKD

Apart from the morbidity, mortality and poor quality of life engendered by CKD and ESRD both in adults (Gorodetskaya et al, 2005; Kimmel and Patel, 2006) and in children (McKenna et al, 2006; Fadrowski et al, 2006), these diseases impose high direct and indirect costs to society. CKD in the pre ESRD phase entails a cost excess of $26.000 per case per year in the USA (Smith et al, 2004). A considerable amount of healthcare funding in Europe is spent on treating dialysis patients. In 2001, it was estimated that in Italy 1.8% of the total health care budget was spent for ESRD patients, i.e. 0.083% of the general population (Pontoriero et al, 2007). Renal transplantation is the most cost-effective renal replacement therapy (White et al, 2008). The costs of treating patients living on a transplant are indeed by one-third to one-quarter lower than those spent on dialysis patients (U.S. Renal Data System, 2005).

Definitions

Whenever possible, the CKD data are presented  according to the internationally accepted definition established by the Kidney Disease Improving Global Outcomes (KDIGO) initiative (Tables 5.7.1 and 5.7.2). Data about CKD in children are presented according to available GFR cut-offs.

Table 5.7.1. KDIGO Definition of Chronic Kidney Disease

Table 5.7.2. Current CKD Classification Based on Severity and Therapy

*Glomerular filtration rate