Chronic kidney disease: global dimension and perspectives

Chronic kidney disease is defined as a reduced glomerular filtration rate, increased urinary albumin excretion, or both, and is an increasing public health issue. Prevalence is estimated to be 8-16% worldwide. Complications include increased all-cause and cardiovascular mortality, kidney-disease progression, acute kidney injury, cognitive decline, anaemia, mineral and bone disorders, and fractures. Worldwide, diabetes mellitus is the most common cause of chronic kidney disease, but in some regions other causes, such as herbal and environmental toxins, are more common. The poorest populations are at the highest risk. Screening and intervention can prevent chronic kidney disease, and where management strategies have been implemented the incidence of end-stage kidney disease has been reduced. Awareness of the disorder, however, remains low in many communities and among many physicians. Strategies to reduce burden and costs related to chronic kidney disease need to be included in national programmes for non-communicable diseases.

Morphology of Balkan endemic nephropathy: current state

Balkan endemic nephropathy (BEN) is interesting renal disease, because of its unique clinical, epidemiological and morphological characteristics: intensive interstitial fibrosis and tubular atrophy without any inflammation. In the present paper we evaluate the incidence of BEN from the morphological point of view for the last decade. Therefore we analyzed material obtained from autopsies, kidney biopsies and nephrectomy due to upper urothelial cancer (UUC) from the patients which were divided into two groups: those with permanent residence in BEN areas and those from nonendemic areas. At the Institute of Pathology, University of Belgrade for the last 15 years we had only 1 autopsy due to BEN out of 6,825. More than 30 years ago there were over 50 autopsy cases of BEN at the same institute. For the last decade we had only 2 kidney biopsies suspected for BEN out of 2,182, but morphologically not confirmed as BEN. However, previously we had over 40 kidney biopsies diagnosed as early or late stage of BEN. At the Clinical Center of Serbia 180 nephrectomies were performed due to UUC. The incidence of UUC for the last five years in BEN regions has significantly decreased, whereas at the same time in non-BEN regions it has remained on the same level. There was no morphological difference of the renal tissue adjacent to tumor between patients from BEN and non-BEN regions. According to our study based on routine pathological work, we could clearly conclude that BEN today is more clinical and epidemiological than a morphological entity.

Survival of patients with transitional cell carcinoma of the ureter and renal pelvis in Balkan endemic nephropathy and non-endemic areas of Serbia

OBJECTIVE

To evaluate the characteristics and survival of patients with upper urinary tract (UUT) transitional cell carcinoma (TCC) in Serbia, followed for >/=5 years or until death.

PATIENTS AND METHODS

From 1998 to 2005 we analysed 114 cases of pathologically confirmed UUT TCC, divided into two groups according to topographical characteristics, and compared their demographic, clinical and pathological characteristics. The influence of various factors on overall 5-year survival of patients with UUT TCC was also tested. The prognostic value of different variables was assessed by univariate and multivariate Cox proportional-hazard models.

RESULTS

The most important change in demographic characteristics of the patients with UUT TCC in Serbia was a similar proportion of patients residing in areas of Balkan endemic nephropathy (BEN) and non-endemic areas. The median (range) follow-up was 67 (46-88) months. The 5-year probability of survival was 51.2 +/- 5.8%. There was a significantly lower probability of 5-year survival for patients with a higher histological grade (P = 0.001), higher T stage (P < 0.001) and tumour size >3 cm (P = 0.001) at diagnosis. In this cohort of patients the independent predictors of a poorer outcome of the disease were being female (hazard ratio, HR, 2.2, P = 0.010), tumour size >3 cm (HR 2.8, P = 0.001) and T3 or T4 stages (HR 3.1, P = 0.001).

CONCLUSION

Comparative analysis of the characteristics of UUT TCC between patients from BEN and non-endemic areas of Serbia showed similarities in demographic, clinical and pathological features. Factors that significantly influenced survival of patients with UUT TCC were being female, tumour size and tumour grade and stage.

Recent data on endemic nephropathy and related urothelial tumors in Croatia

Endemic nephropathy (EN) is a renal disease of unknown etiology. In Croatia it occurs in the rural population in 14 villages located in the western part of Brodsko-Posavska county. This region also has an unusually high incidence of otherwise rare upper urothelial cancers. Between 1991 and 2002 the average general mortality for both sexes in the endemic region was 10.3 per thousand and the specific mortality for patients with EN was 0.65 per thousand (M 0.58/10((3)), F 0.72/10(3)). The average age of death of patients with EN was 69.2 years (M 67.7, F 70.3), which is similar to the life expectancy for the rest of the population in the county (67.8, M 64.4, F 71.8). This life expectancy is significantly higher than in the period 1957-1960 when the average age of EN-related death was 45.1 years. Between 1995 and 2002, in contrast to both Croatia as a whole and the respective county, the specific mortality with tumors of the pyelon and ureter in the endemic region was much higher in women than in men (9.020 and 4.697 per 100,000, respectively). The specific mortality of all patients with urothelial tumors was 14 times higher in the endemic region than in Brodsko-Posavska county and 55 times higher than in Croatia overall. The much higher specific urothelial-tumor mortality in women than in men (in contrast to the rest of the country) and the higher specific EN mortality indicate that the causative agent of the two nosological entities is the same.

Survival of Balkan endemic nephropathy patients

The retrospective cohort study comprised 97 Balkan endemic nephropathy (BEN) and BEN-suspected patients discovered in 1971 in the field examination in the village of Sopić, one of the regions most frequently affected by the disease. Our aim was to determine the outcome of the disease in patients and to compare the survival of BEN-suspected and BEN-manifested patients and the survival of their kidneys. The mean survival time was 16.4 years for all patients (95% CI 14.51-18.21) and 23.1 years for suspected and 13.3 years for manifested patients (log-rank = 19.46; d.f. = 1; p < 0.001). According to our results, it can be concluded that BEN is characterized by slow course and prolonged evolution and that the prognosis was consistently better for BEN-suspected than for BEN-manifested patients.

Balkan endemic nephropathy: a decreasing incidence of the disease

Balkan endemic nephropathy (BEN) is a chronic tubulointerstitial kidney disease prevalent in Serbia, Bosnia, Croatia, Bulgaria and Romania. This study investigates the incidence of BEN patients on dialysis with end-stage kidney disease (ESKD), and BEN-associated mortality in endemic areas around the South Morava River in Serbia from 1978 to 1997. In the last 10 years a marked decrease in the incidence of ESRD and BEN-induced mortality has been documented in the region. This study shows a significantly decreased incidence of BEN in endemic areas in South Serbia. Since the effects of etiological agent(s) on renal function in children from families in endemic areas was demonstrated in the early nineties and the disease seems to have an endemic-epidemic profile, the possibility of another epidemic outbreak in the future cannot be excluded.

Epidemiology of Balkan endemic nephropathy

The first outbreak of Balkan endemic nephropathy (BEN) was reported between 1955 and 1957, initially in Serbia and soon afterwards in Croatia and in Bosnia and Herzegovina. The disease appears to be of a focal nature. In Yugoslavia at least six foci are known, generally along major rivers of the Danubian river basin, in areas that have often been flooded in the past and even today suffer from high ground waters. The prevalence rate of the disease is reported to be between 2 and 10%. In the endemic area of Croatia, a systematic survey of 'in-the-field' cases of the disease since 1975 has shown a prevalence between 0.5 and 4.4%. When suspected cases are also included the prevalence rises to 20% or more. Specific mortality (based on official statistics) during the period 1957-1984 averaged 1.54/1000 per annum, but some studies have shown that mortality is actually more than twice as high as this figure. More women are affected than men; women also more frequently die of BEN than men. Lethality is extremely high. A striking feature of BEN is the familial occurrence of the disease. Incidence does not seem to be connected with ethnic group differences. Immigrants into the endemic area may also contract the disease. An increased incidence of malignant tumours of the urinary tract has been recorded in populations living in endemic areas. Epidemiological characteristics suggest that the disease is contracted in the domestic situation, or possibly from other family members. Factors to be considered are food, water or long close contact. It is also possible that the disease is contracted outside the house, in connection with farming activities, since the affected persons are almost exclusively farmers.

Pathomorphology of Balkan endemic nephropathy

Within the county of Slavonski Brod, Yugoslavia hyperendemic areas of Balkan endemic nephropathy (BEN) have been recognized for a long time. As the Department of Pathology and Forensic Medicine of the Medical Centre in Slavonski Brod is responsible for all diagnostic post-mortem examinations in the county, and at the same time is engaged in surgical pathological diagnosis, a considerable amount of material relating to BEN and concomitant urinary-tract tumours has been collected during a 16-year period. This material has been classified and used for pathological, anatomical and histological investigations. In this paper the most relevant findings are described and briefly discussed, without the intention to speculate on possible aetiology of BEN. As the origin of BEN and of the high frequency of urinary tumours among the people from the endemic areas are still unexplained, and uniform criteria for the pathomorphological diagnosis of BEN are badly needed, the proposal to set up an archive encompassing cases from all the centres investigating BEN is supported.

Beta 2-microglobulinuria as a predictor of death in a population exposed to Balkan endemic nephropathy

During the year 1974, urinary beta 2-microglobulin (beta 2mu) was measured at monthly intervals using the first-morning urine sample of randomly selected individuals from the BEN affected village of Petka (416 persons) and from the nearby situated control village of Stubica (216 persons). Initial compliance was complete; over 90% of villagers had at least 10 tests performed. beta 2mu, as assessed by radial immunodiffusion (RID), was repeatedly (at least twice) positive in 12% and 1.4% of the populations of the endemic and control villages, respectively. Over the 15 years of follow-up (1974 to 1988), none from the control village developed BEN, while many medical records of the cohort exposed to BEN contained data suggestive of BEN. Death from/with BEN was used as a measure of outcome. Incidence density of 12 was 3.3 per 1000 person/years of observation (19/5723). A single positive beta 2mu test was a sensitive predictor of BEN death (sensitivity = 89.5%). Selecting two or more positive tests as the cut-off point, the specificity and positive predictive value were considerably increased. Using the sulfosalicylic acid test for detection of significant proteinuria, a similar level of validity indices was reached only by four testings.