Original Paper Blood Purif 2008;26:381–385 DOI: 10.1159/000137275
Received: January 30, 2008 Accepted: January 30, 2008 Published online: June 6, 2008
Epidemiology of Chronic Kidney Disease in Central and Eastern Europe Bolesław Rutkowski Ewa Król Department of Nephrology, Transplantology and Internal Diseases, Medical University of Gdansk, Gdansk , Poland
Key Words Chronic kidney disease ⴢ Renal replacement therapy ⴢ Epidemiology ⴢ PolNef study
Abstract Background: The world population suffering from endstage renal disease (ESRD) is growing. The epidemiology of ESRD is relatively well documented, but data on chronic kidney disease (CKD) are missing, especially in Central and Eastern Europe (CEE). Early detection of CKD is important because it allows introduction of the therapy that slows the progression of CKD. The aim of the present study was to estimate the prevalence of CKD and ESRD in CEE. Methods: Our data are based on two independent surveys: one concerns epidemiology of CKD, the other ESRD. Moreover, we present rough results from the pilot study PolNef on early detection of CKD, performed in North Poland. Estimated glomerular filtration rate, albuminuria and ultrasound examination were the main diagnostic tools. Results: Only limited data from South-East Hungary and North Poland were available: the number of CKD patients under nephrological care and on dialysis. According to the PolNef study, using a dipstick test albuminuria was detected in 15.6% of participants but dropped to 11.9% when it was measured using the turbidimetric method. Conclusions: Data concerning epidemiology of CKD in CEE are missing. Epidemiology of ESRD in CEE seems to be similar to that in Western Europe. PolNef is the first study dealing with renal epidemiological problems
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in CEE. It shows that renal epidemiological problems in CEE are comparable to those of the other parts of the world. Studies concerning CKD epidemiology in different CEE countries are necessary to confirm that the incidence and prevalence of CKD are similar to those in Western Europe and other parts of the globe. Copyright © 2008 S. Karger AG, Basel
Introduction
Chronic kidney disease (CKD) is a worldwide underdiagnosed public health problem with increasing incidence and prevalence, high costs and poor outcome [1, 2]. In the last years, CKD has become a major social health problem because of the aging of the population, the high incidence of diabetes and often the asymptomatic course resulting from inadequate diagnosis of early stages of renal damage. Epidemiological studies far more often concern renal replacement therapy (RRT) than CKD. The number of patients on RRT has gradually increased over the last decades and the number of patients on RRT is predicted to double during the next 10 years [3]. Therefore, strategies to reduce the incidence of end-stage renal disease (ESRD) require effective methods of screening
Presented at the 10th International Conference on Dialysis ‘Advances in CKD 2008’, January 15–17, 2008, Cancun, Mexico.
Bolesław Rutkowski Department of Nephrology, Transplantology and Internal Diseases Medical University of Gdansk, Debinki 7 PL–80-211 Gdansk (Poland) Tel. +48 58 349 2505, Fax +48 58 346 1186, E-Mail
[email protected]
early in the disease process. Intervention in early stages of CKD seems to be more effective to prevent or delay progression of CKD. Microalbuminuria has been used as a screening tool, but by itself is not a sufficient instrument [4]. It is worth pointing out that albuminuria and decrease in estimated glomerular filtration rate (eGFR) were used as two basic markers for the new classification of CKD proposed by the Kidney Disease Outcomes Quality Initiative of the National Kidney Foundation and introduced widely after slight modification by the Kidney Disease Improving Global Outcomes international community [5]. The usefulness of these two markers (i.e. presence of albuminuria and diminished eGFR) was shown in several epidemiological studies. In NHANES III, prevalence of albuminuria in the general adult population of the United States was 9% and prevalence of CKD 11% [6]. Similarly, in AusDiab study, albuminuria occurred in 7% of the general Australian population, and CKD in 11% [7]. In the Japanese Takahata study, both frequency of albuminuria (almost 14%) and frequency of CKD (nearly 29%) were high in the general population [8]. In Europe, the epidemiology of CKD was investigated in the Netherlands (PREVEND study) [9], Norway (HUNT Study) [10] and Italy (Gubbio Study) [11]. All these studies have shown that CKD has to be recognized in at least 7% of the general population. At the same time, in the Italian study a significant increment of such abnormalities in elderly people of up to 35% was shown [11]. The aim of this study was to investigate the CKD problem in Central and Eastern Europe (CEE).
Subjects and Methods Data presented in this study were based on two independent surveys. Special questionnaires were completed by the members of the National Renal Registries or key persons from the National Nephrological Society in CCE countries. Some information concerning ESRD epidemiology were corrected or validated using recent reports published by the National Renal Registries [12–16] or the ERA-EDTA Registry [17]. All data showing results of the pilot epidemiological investigation PolNef were based on the studies performed in 2004–2005 in Starogard Gdański, a 60,000inhabitant city district in North Poland, which was randomly chosen from the two districts with a population of 50,000–100,000 in the Pomeranian administrative region. 9,700 invitations for taking part in the PolNef study were sent to adult inhabitants randomly chosen from the address list. 2,476 (25.5%) participants responded, brought a morning urine sample, allowed for blood pressure measurement, and filled in a questionnaire on demographic characteristics, weight and height, symptoms of kidney diseases, medications taken, and coexistence of other diseases, especially hypertension, diabetes and cardiovascular diseases.
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The algorithm for further evaluation of every participant was described in detail in our previous publications [18, 19]. A dipstick test for microalbuminuria (Micral test II, Roche Diagnostics Ltd., UK) was performed to detect albumin in the first morning urine sample. The cut-off point for this test is albumin concentration in urine equal to 20 mg/l. Moreover, albumin concentration in urine was measured in the laboratory before renal consultation from a separate urine sample by the turbidimetric method: Multigent Microalbumin assay, on the Architect ci 8200 system (Abbott Laboratories, Inc.). Serum creatinine was measured using the modified method of Jaffe’s reaction in an automated Architect ci 8200 analyzer without creatinine assay calibration from the MDRD laboratory. The abbreviated MDRD formula was used to estimate GFR in all individuals qualified for renal consultation. Hypertension was diagnosed based on the actual hypotensive treatment or on the medium value (6140/90) of three separate measurements of blood pressure with adequate cuff. Ultrasound examinations were performed by a nephrologist experienced in ultrasound diagnosis with phased-array transducer 2–5 MHz (B&K 2002 Panther). Body mass index (BMI) was calculated as the ratio of weight in kilograms to height in meters squared. A multivariate logistic regression model was applied in order to investigate the relationship between clinical characteristics such as sex, diabetes, age divided in groups, nocturia, hypertension, smoking, BMI, and the odds to detect albuminuria. A backward selection procedure, with p ! 0.1 used for retention in the model, was performed in order to identify important factors at the 0.05 level of statistical significance. The Hosmer-Lemeshow test was used to check the goodness of fit of the model. The analyses were performed using StataCorp statistical software, version 8.
Results
Epidemiology of CKD It is necessary to underline that strict epidemiological studies concerning incidence or prevalence of CKD have never been performed in the CEE region and detailed data from these countries are still missing. According to the results of our survey, only some data from South-East Hungary were available, which can be helpful only from a practical point of view. This region of Hungary includes four counties: Csongrad, Bacs-Kiskun, Bekes and Szolnok. The number of CKD patients under nephrological care per one million population (p.m.p.) is 6,685.4 compared to 450 p.m.p. on dialysis (1,780,000 inhabitants, 11,900 CKD patients under nephrological care [Šonkody, pers. commun.]). In our Pomeranian region, the number of CKD patients under nephrological care is 3,235.6 p.m.p., on dialysis 387 p.m.p. (2,199,000 inhabitants, 7,086 CKD patients) [20]. Some information concerning epidemiology of specific kidney diseases is enclosed in two studies from renal biopsy registries in the Czech Republic and Romania [21, 22]. The first, although not a perfect study on epidemiology of CKD in Central EuRutkowski/Król
Table 1. General characteristics of the PolNef study results
Participants Invited Participated Female/male Mean age 8 SD Mean BMI 8 SD Albuminuria Dipstick test (Micral test II) Concentration in urine (turbidimetric method) Hypertension Diabetes Hypertension Total With albuminuria With CKD Diabetes mellitus Total With albuminuria With CKD CKD Total With albuminuria With hypertension With diabetes eGFR in CKD by abbreviated MDRD, ml/min/1.73 m2 >90 60–89.9 30–59.9 15–29.9
