Time trends in Balkan endemic nephropathy incidence in the most affected region in Serbia, 1977-2009: the disease has not yet disappeared

Background. Balkan endemic nephropathy (BEN) is a familial chronic kidney disease, which occurs only in some regions of the Balkan Peninsula. The aim of this study was to determine the main epidemiological features of BEN in the Kolubara region, the most affected region in Serbia, and to try to elucidate the controversial issue of whether or not BEN is tapering off. Methods. To evaluate the BEN incidence rates in the municipality of Lazarevac over a 33-year period (1977 - 2009), we used data of BEN notifications from the BEN Registry located in the Special Hospital for Endemic Nephropathy, Lazarevac. Population data were obtained from the 1981, 1991 and 2002 national censuses by interpolation. BEN incidence rates were standardized according to the European standard population, and their trends were assessed by Poisson regression model and joinpoint analysis. Results. The age-adjusted BEN incidence rates combined for both sexes over a 33-year period (1977 - 2009) fitted a significant quadratic (U-shaped) trend (y = 58.44 - 3.76 + 0.10x(2), P = 0.026). Joinpoint analysis showed that the overall age-standardized BEN incidence rates significantly decreased in the first decade of the observed period (1977-89) by an average of 10.0% annually, while a nonsignificant increase of 3.9% per year was recorded in the last two decades (1989 - 2009). Conclusions. Our results revealed that BEN still exists in the Kolubara region. The predicted disappearing scenario of this still mysterious disease has not happened.