Open questions on Balkan nephropathy.

The prevalence of the disease was stable over many years, but now appears to decline in most affected settlements w1x. Some authors also suggest that the incidence of BEN decreases w1,2x and that it appears to be tapering off; others, however, describe a stable incidence of BEN w3x. The question arises on different epidemiological characteristics of the disease in different endemic regions. In search of an answer to this question a retrospective analysis of the incidence of haemodialysis BEN patients was undertaken in four haemodialysis centres situated in three different endemic regions over the period 1991–2000. The medical files of haemodialysis patients treated in Lazarevac (Kolubara River), Nis and Leskovac (South Morava River) and Pozarevac (Pek River) were used in this study. The incidence of haemodialysis patients with BEN from endemic villages was compared with the incidence of patients suffering from other renal diseases from the same endemic villages. Non-standardized rates per 1000 inhabitants were calculated. The incidence of BEN patients in ESRD, who started haemodialysis, was different in three endemic regions already known as differently affected endemic foci. However, during the last decade the incidence of haemodialysis BEN patients remained stable in all three regions (Figure 1a). In the same period, the incidence of haemodialysis patients suffering from other renal diseases and living in the same endemic villages (mean incidence for three regions 0.035–0.28) was lower than the incidence of BEN patients on haemodialysis (0.22–0.58) (Figure 1b). These results correspond with those reported by Cukuranovic et al. w4x but these authors pointed out a marked decrease of the incidence of BEN in end-stage renal disease (ESRD) in the last 10 years as compared with the previous decade. BEN is a slowly progressive disease and patients usually start haemodialysis in their sixties. Therefore, although our data demonstrate a stable incidence of BEN in ESRD it only indicates that BEN is preserved. In order to answer the question above, monitoring of the incidence of BEN in the early stage is more important. A recent study in the Kolubara River area has discovered new BEN or BEN-suspected cases and the authors consider that BEN is not tapering off w5x. However, early diagnosis of BEN is associated with the following unsolved questions on BEN—criteria for a correct diagnosis.