Ante Cvitković

Consensus statement on screening, diagnosis, classification and treatment of endemic (Balkan) nephropathy

Currently used diagnostic criteria in different endemic (Balkan) nephropathy (EN) centers involve different combinations of parameters, various cut-off values and many of them are not in agreement with proposed international guidelines. Leaders of EN centers began to address these problems at scientific meetings, and this paper is the outgrowth of those discussions. The main aim is to provide recommendations for clinical work on current knowledge and expertise. This document is developed for use by general physicians, nephrologists, urologist, public health experts and epidemiologist, and it is hoped that it will be adopted by responsible institutions in countries harboring EN. National medical providers should cover costs of screening and diagnostic procedures and treatment of EN patients with or without upper urothelial cancers.

Could Disappearance of Endemic (Balkan) Nephropathy Be Expected in Forthcoming Decades

Background/Aims: An epidemiological survey of endemic nephropathy (EN) was performed in endemic Croatian areas and the current prevalence was compared to that reported for the same villages several decades ago. Methods: A total of 2,487 adult farmers from 6 endemic villages and 3 non-endemic villages were enrolled. An extensive epidemiological questionnaire, clinical examination and laboratory analyses of blood and urine were performed. According to the modified WHO criteria, participants were classified into diseased, suspected of having EN, and those at risk of developing EN. Results: The overall prevalence of EN in the Croatian areas was 1.0%, ranging between 0.3 and 2.3% in different villages. Those suspected of having EN amounted to 3.9%. In the endemic villages a decreasing trend in the prevalence of EN was observed comparable to the results obtained in previous surveys. It is interesting to note that no EN patients were recorded in the endemic village of Dubočac. Conclusion: The prevalence of EN in the endemic Croatian areas appears to be decreasing. For the first time, we failed to detect any EN patients in a village that was previously considered endemic, which might indicate that EN is diminishing.

Chronic Dietary Exposure to Aristolochic Acid and Kidney Function in Native Farmers from a Croatian Endemic Area and Bosnian Immigrants

BACKGROUND AND OBJECTIVES Improvements in agricultural practices in Croatia have reduced exposure to consumption of aristolochic acid-contaminated flour and development of endemic (Balkan) nephropathy. Therefore, it was hypothesized that Bosnian immigrants who settled in an endemic area in Croatia 15-30 years ago would be at lower risk of developing endemic nephropathy because of reduced exposure to aristolochic acid. To test this hypothesis, past and present exposure to aristolochic acid, proximal tubule damage as a hallmark of endemic nephropathy, and prevalence of CKD in Bosnian immigrants were analyzed. DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS In this cross-sectional observational study from 2005 to 2010, 2161 farmers were divided into groups: indigenous inhabitants from endemic nephropathy and nonendemic nephropathy villages and Bosnian immigrants; α-1 microglobulin-to-creatinine ratio >31.5 mg/g and eGFR<60 ml/min per 1.73 m(2) were considered to be abnormal. RESULTS CKD and proximal tubule damage prevalence was significantly lower in Bosnian immigrants than inhabitants of endemic nephropathy villages (6.9% versus 16.6%; P<0.001; 1.3% versus 7.3%; P=0.003, respectively); 20 years ago, Bosnian immigrants observed fewer Aristolochia clematitis in cultivated fields (41.9% versus 67.8%) and fewer seeds among wheat seeds (6.1% versus 35.6%) and ate more purchased than homemade bread compared with Croatian farmers from endemic nephropathy villages (38.5% versus 14.8%, P<0.001). Both Croatian farmers and Bosnian immigrants observe significantly fewer Aristolochia plants growing in their fields compared with 15-30 years ago. Prior aristolochic acid exposure was associated with proximal tubule damage (odds ratio, 1.64; 95% confidence interval, 1.04 to 2.58; P=0.02), whereas present exposure was not (odds ratio, 1.31; 95% confidence interval, 0.75 to 2.30; P=0.33). Furthermore, immigrant status was an independent negative predictor of proximal tubule damage (odds ratio, 0.40; 95% confidence interval, 0.19 to 0.86; P=0.02). CONCLUSIONS Bosnian immigrants and autochthonous Croats residing in endemic areas are exposed significantly less to ingestion of aristolochic acid than in the past. The prevalence of endemic nephropathy and its associated urothelial cancers is predicted to decrease over time.

Is herbal tea consumption a factor in endemic nephropathy

Endemic (Balkan) nephropathy (EN) is a chronic tubulointerstitial nephropathy frequently associated with upper urothelial cancer exclusively affecting farming villagers [1–3]. Based on our results, EN is considered to be an environmental form of aristolochic acid nephropathy (AAN) [1–3]. AAN was first reported in 1993 in Belgium and subsequently more AAN cases were reported worldwide as AA has been an integral part of traditional herbal medicines [4]. The extent of this problem was recently documented in Taiwan where precise data on prescriptions of herbal products containing AA is available [5]. Aristolochia spp. has been used for more than 2,000 years in the practice of traditional medicine and European physicians were familiar with the use of this plant as well. After its intrinsic toxicity became known, importing Aristolochia herbs was banned in many countries, including Croatia. Nevertheless, products containing AA remain a part of traditional medicine and are sold in many countries that do not have strict control protocols. Recently we reported that AA DNA adducts were present in 95 % of patients with EN who underwent surgery for upper urothelial cancers [2] and affirmed the idea that bread contaminated with AA might be the cause of EN [6, 7]. However, the causative relationship between AA and EN again raised the question whether bread intake is the only route of ingestion or whether AA was ingested also in EN as a part of folkloric medicine. Gluhovschi et al. [8] reported that although therapeutic remedies based on AA products are used in the EN affected area in Romania, no relationship between these remedies and the development of EN or of tumors was observed. However, they used HPLC for detection of AA in plasma, which is less sensitive than the mass spectrometry we recently used in tissue samples [1, 2]. In addition, when re-analyzing their data, it does appear that AA was used more frequently in the endemic area. In our opinion, this leaves the question whether herbal tea may play a role in EN still unanswered. In our preliminary study we failed to find any evidence in the group of 1,041 Croatian farmers that herbal tea or traditional medicine use is related to EN [9]. The observed differences between

Reliability of CKD-EPI predictive equation in estimating chronic kidney disease prevalence in the Croatian endemic nephropathy area.

Introduction Chronic kidney disease (CKD) is a significant public health problem and it is not possible to precisely predict its progression to terminal renal failure. According to current guidelines, CKD stages are classified based on the estimated glomerular filtration rate (eGFR) and albuminuria. Aims of this study were to determine the reliability of predictive equation in estimation of CKD prevalence in Croatian areas with endemic nephropathy (EN), compare the results with non-endemic areas, and to determine if the prevalence of CKD stages 3-5 was increased in subjects with EN. Materials and methods A total of 1573 inhabitants of the Croatian Posavina rural area from 6 endemic and 3 non-endemic villages were enrolled. Participants were classified according to the modified criteria of the World Health Organization for EN. Estimated GFR was calculated using Chronic Kidney Disease Epidemiology Collaboration equation (CKD-EPI). Results The results showed a very high CKD prevalence in the Croatian rural area (19%). CKD prevalence was significantly higher in EN then in non EN villages with the lowest eGFR value in diseased subgroup. Conclusions eGFR correlated significantly with the diagnosis of EN. Kidney function assessment using CKD-EPI predictive equation proved to be a good marker in differentiating the study subgroups, remained as one of the diagnostic criteria for EN.

Simultaneous chickenpox and measles infection among migrant children who stayed in Italy during the second half of June 2011.

We are reporting on a household outbreak of measles, in which cases of simultaneous measles and chickenpox infection occured in children of a family who resided in Italy during the incubation period (June 2011). In three children, fever and generalized confluent macular rash were the dominant symptoms. Serology testing revealed simultaneous measles and chickenpox infection in four children.

Upper urothelium carcinomas in Croatian endemic area

SummaryBackground/AimsEndemic nephropathy (EN) is a chronic tubulointerstitial disease. Strong association between EN and urothelial carcinoma was noted as early as 40–50 ago. The aim of the study was to determine and compare specific mortality and morbidity of renal pelvis and ureter (upper urothelium) carcinoma (UUC) among Croatia as a whole, Brod-Posavina County, and Croatian endemic area.MethodsData on UUC mortality and morbidity were analyzed. Indirect standardization was employed on data comparison by calculating standardized mortality ratio and morbidity ratio.ResultsOur study results showed the specific mortality rate in the endemic area to be 26.3-fold and 7.3-fold the rate recorded in Croatia and Brod-Posavina County, respectively. The mean standardized mortality ratio obtained by indirect standardization yielded an 8-fold and 32-fold risk of death from UUC in the endemic area vs. Brod-Posavina County and Croatia as a whole, respectively. These data revealed the specific morbidity in the Croatian endemic area and Brod-Posavina County to be 13.95-fold and 3.78-fold the morbidity recorded at the national level, respectively. The standardized morbidity ratio also showed the risk of developing UUC in the Croatian endemic area to be 3.75-fold the risk in Brod-Posavina County and 16.4-fold the risk in Croatia.ConclusionsThese results showed that specific mortality and morbidity as well as standardized morbidity ratio and standardized mortality ratio were higher in Croatian endemic area than in Brod-Posavina County and Croatia.ZusammenfassungHintergrund/ZieleDie endemische Nephropathie (EN) ist eine chronische tubulo-interstielle Erkrankung. Schon vor 40–50 Jahren wurde ein deutlicher Zusammenhang zwischen EN und dem Urothelkarzinom festgestellt. Ziel dieser Studie war es, die spezifische Mortalität und Morbidität des Nierenbeckens und des Ureters (oberes Urothel) zu erfassen und die Daten von Gesamt-Kroatien, sowie von der Provinz Brod-Posavina mit denen des Endemiegebiets Kroatiens zu vergleichen.MethodikDie Daten über die Mortalität und Morbidität des Nierenbeckens und des Ureterkarzinoms (UK) wurden analysiert. Beim Vergleich der Daten wurde eine indirekte Standardisierung verwendet, wobei die standardisierten Mortalitätsquotienten und Morbiditäts- quotienten errechnet wurden.ErgebnisseUnsere Studie zeigte, dass die spezifische Mortalitätsrate im Endemiegebiet das 26,3 fache der Rate von Gesamt-Kroatien bzw. das 7,3 fache der Rate von der Provinz Brod-Posavina betrug. Der mittlere standardisierte Mortalitätsquotient, durch indirekte Standardisierung errechnet, ergab für das Endemiegebiet ein 8-faches bzw. 32-faches Sterberisiko im Vergleich zu dem für Bewohner der Provinz Brod-Posavina bzw. von Gesamt-Kroatien erhobenen. Die Studie zeigt überdies, dass die spezifische Morbidität im kroatischen Endemiegebiet das 13,95 fache und in der Provinz Brod-Posavina das 3,78 fache im Vergleich zu Gesamt-Kroatien beträgt. Der standardisierte Morbiditätsquotient zeigte auch, dass das Risiko, ein UK zu entwickeln, im kroatischen Endemiegebiet 3,75 fach höher ist als in der Provinz Brod-Posavina und im Vergleich zu Gesamt-Kroatien sogar 16,4 fach höher!SchlussfolgerungenUnsere Ergebnisse zeigen, dass die spezifische Mortalität und Morbidität, sowie die standardisierten Morbiditäts- und Mortalitätsquotienten im kroatischen Endemiegebiet höher waren als in der Provinz Brod-Posavina beziehungsweise als in Kroatien.

Prevalence, treatment and control of hypertension in a Croatian endemic nephropathy area.

Background: Hypertension is not considered to be a characteristic of endemic nephropathy (EN). Recent observations suggested that it might be more prevalent than it was reported before. Aim: The aim of our study was to analyze prevalence, treatment and control of hypertension in a Croatian endemic area. Methods: In the present cross-sectional study, 1,602 farmers were enrolled, 1,246 from EN and 356 from control villages. Epidemiological and medical histories were taken and clinical and laboratory examinations performed for kidney function. Blood pressure was measured following the ESH/ESC guidelines. Results: The prevalence of hypertension in EN villages was higher than in control (50.8 vs. 46.5%, p = 0.005). There was no difference in overall treatment, control of all and treated hypertensives between the villages. In all villages, women were treated more than men (EN 41.6 vs. 28.4%, p < 0.001; control 46.4 vs. 27.3%, p < 0.001), but better control of treated was achieved in men (EN 24.7 vs. 17.4%, p = 0.002; control 29.6 vs. 15.5%, p = 0.002). Women had lower income and level of education than men (p < 0.01). Conclusion: Hypertension is highly prevalent in endemic villages. In all villages, men had better blood pressure control despite being treated less. This finding could be explained by poorer education and income in women.

Angiotensin-converting enzyme gene polymorphism and N-Acetyl-β-D-glucosaminidase excretion in endemic nephropathy.

Background: Tubular proteinuria and enzymuria are hallmarks of endemic nephropathy (EN). The role of I/D angiotensin convertase (ACE) gene polymorphism has not yet been elucidated in this peculiar chronic tubulointerstitial nephritis, and our aim was to investigate the role of this polymorphism in EN focusing on the urinary N-acetyl-β-D-glucosaminidase (NAG) excretion, a biomarker of proximal tubular damage. Methods:ACE genotype and allele frequencies were determined in 229 farmers (147 women and 82 men) from an endemic Croatian village. The farmers were stratified according to the WHO criteria into the following subgroups: those ‘at risk’ for EN (n = 37), ‘suspected of having EN’ (n = 57), and ‘others’ (n = 135). Results: There were 74 (32.3%) subjects homozygous for the D allele, 99 (43.2%) heterozygous (ID genotype) and 56 (24.4%) homozygous for the I allele. No differences in allele frequency were found between the established WHO subgroups (p > 0.05). In the whole group, DD subjects had significantly higher values of diastolic blood pressure (p = 0.003) and urinary NAG than subjects with ID and II genotype (5.5 ± 1.2 vs. 4.0 ± 3.0 vs. 3.8 ± 4.2, respectively; p = 0.023). The highest values of serum creatinine (p = 0.02), proteinuria (p = 0.03) and urinary NAG (6.0 ± 3.7 vs. 3.7 ± 2.1 vs. 3.0 ± 1.6, respectively; p = 0.008) were observed in those suspected of having EN group with the DD genotype. Conclusion:ACE gene polymorphism is not a risk factor for EN. However, it might influence the clinical course of EN, and increased excretion of NAG might be a prognostic marker of this chronic tubulointerstitial nephritis.

METABOLIC SYNDROME AND EARLY KIDNEY DAMAGE IN RURAL POPULATION: PP.34.388

Objective: To analyze prevalence of metabolic syndrome (MS) in early phases of chronic kidney disease (CKD) and effect of its components on early renal impairment. Design and Method: In this survey 1003 farmers from continental, rural part of Croatia were enrolled (386 men; 617 women; average age 52(30-95); females were older(Mann-Whitney test:z=3,6;p < 0,001). After extended questionnaire and clinical exam, fasting blood was drawn and second morning urine sample was collected (for microalbuminuria (MA) and alpha1 microglobulinuria (α1MG). Blood pressure (BP) was measured following the ESH/ESC guidelinies, metabolic syndrome (MS) was defined according to the NCEP ATP III recommendations. Subjects were classified into the CKD stages groups according to the KDOQI classification. Results: In general rural population prevalence of MS was 22,6% (30% men, 70% women; p = 0,045). Prevalence of MS was significantly higher in subjects with CKD stage 3 as compared to the CKD stage 1 (χ2 = 4;p = 0,045) as well as in subjects with MA compared to those with normal values (χ2 = 5,85;p = 0,016), while there was no difference between subjects with elevated and normal values of α1MG (χ2 = 0,19;p = 0,662). We observed significant difference between stages CKD 1 and 3 in BP (χ2 = 15,6;p < 0,001), waist circumference (WC) (χ2 = 26,8;p < 0,001), fasting blood glucose (FBG) (χ2 = 22;p < 0,001), triglycerdies (TG) (χ2 = 7,4;p = 0,024) and HDL level (χ2 = 0,621;p < 0,001). Significant differences in BP, FBG, WC and TG were observed between subjects with MA in comparison with normal values (χ2 = 8,1;p = 0,004; χ2 = 23,2;p < 0,001; χ2 = 6,85;p = 0,009; χ2 = 9,0;p = 0,003, respectively). Multivariate age-adjusted OR for development of MA was significant for FBG and TG (OR 2(1,43–2,8);p < 0,001; OR 1,59(1,02–2,5);p = 0,043, respectively). Only systolic BP was significantly associated with α1MG(χ2 = 2,59;p < 0,001) with multivariate age-adjusted OR for development of α1MG of 1,52 (1,01–2,28);p = 0,043. Conclusions: Prevalence of MS and its components increase with CKD stage. MS, and especially FBG and TG are risk factors for MA while systolic BP is a risk factor for proximal tubule damage i.e. α1MG.