Is the incidence of Balkan endemic nephropathy decreasing?

Balkan Endemic Nephropathy (BEN) is a non-inflammatory, slowly progressing, familial, primarily tubulo-interstitial, bilateral renal disease that affects rural populations in several Balkan countries. Our study describes a time trend of the incidence of BEN in eight villages of Vratza District, Bulgaria, for the period 1965-1987, based on three various data sets. The data suggest that after the initial peak between 1967 and 1970, the incidence remained quite stable for the period 1970-1984, and declined after 1984. However, the study also demonstrates under-recording of BEN cases and less complete case identification, especially after 1979. Migration of population might also have contributed to an apparent decline in registered cases. We detected cases of BEN in villages that previously were BEN-free. We recommended a rigorous monitoring of BEN in all afflicted countries, before concluding that the incidence of BEN is decreasing.

Balkan endemic nephropathy in Vratza, Bulgaria, 1964-1987: an epidemiologic analysis of population-based disease registers.

Balkan Endemic Nephropathy (BEN), first described in 1956 in Vratza region, Bulgaria, may result from prolonged, chronic exposure to environmental toxicants, but the underlying etiologic factors remain elusive. There has been no recent systematic characterization of the epidemiology of this disease. Recently, it has been suggested that the incidence of the disease is decreasing. We therefore abstracted data from registers of patients in 21 affected villages and the town of Vratza, Bulgaria maintained from 1964 through 1987. In 1964, the prevalence of BEN was 6.0 per 1000 inhabitants; among residents of the affected villages, the prevalence was 12.3 per 1000. From 1965 to 1975 the incidence rate was 0.7 per 1,000 person-years, and from 1976 to 1987 the incidence rate was 0.3 per 1,000 person-years (rate ratio 0.43; p < 0.001). Incidence was much lower in Vratza town; among residents of affected villages, the period-specific rates were 1.7 and 0.8 per 1,000 per year, respectively (rate ratio 0.47; p < 0.01). These trends were consistent across all villages for which registers were maintained. Median survival following registration increased from 2.0 to 5.0 years over the same period (p < 0.001). BEN appears to be decreasing in incidence in this region.