| Balkan Endemic Nephropathy (BEN), first described in 1956 in Vratza District, Bulgaria, may result from prolonged, chronic exposure to environmental toxicants, but the underlying etiologic factors remain elusive. There has been no recent characterization of the epidemiology of this disease. Our study conducted in May 2000 in Vratza District aimed to assess prevalence, incidence, age and gender distribution, survival time and life expectancy of BEN. The project also investigated a possible association of BEN with ochratoxin A. The results of the study suggest a decline of incidence of BEN in the endemic area over the period 1964--1987---from 0.7 per 1000 to 0.3 per 1000. Reasons for the decline in incidence may be incomplete case identification, reduced efforts of screening, and diminished public health interest. The percentage of underreported cases rose from 6.0% for the period 1965--1969 to 18.9% in 1980--1984. Survival and life expectancy increased significantly over the same period, from 1.7 to 6.5 years; life expectancy increased from 59 to 68.7 years. Age at first diagnosis was raised from 53.9 to 56.3 years. Therefore the increase in survival was due to actual prolongation, not lead-time bias. Ochratoxin A could falsely be associated with BEN, due to behavior bias expressed by a modification of food storage in villages affected by BEN, but not by residents of non-BEN villages. |
