Browsing by Author "Naumovic, T. (6602346533)"

During the year 1974, urinary β2-microglobulin (β2mu) 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. β2mu, 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 β2mu 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.

Baseline data from a study run in 1974, which comprised beta2-microglobulinuria (β2mu) measurements at monthly intervals from 416 members in 112 households from the BEN affected village of Petka, were compared with the results of two subsequent, cross sectional studies. In June 1988, retesting involved 320 available persons from the same households. Another collection of 284 urine specimens took place in October 1989. Prevalence of tubular proteinuria was the same in 1988 and 1989 as it was in 1974, indicating that the level of exposure to nephrotoxic agent did not change over time. Over 94% of the individuals who were always β2mu negative in 1974 remained negative in 1988. By contrast, over two thirds (68.7%) of those who were positive two or more times 14 years ago, tested positive upon re-examination in 1988. Particular interest arises from the data on those initially repeatedly positive persons in whom the overt disease did not occur over time; moreover, some appeared to be unaffected in 1988 and 1989 according to our set of laboratory criteria. The results suggest occasional slow progression and even possible reversibility of tubular lesions in individuals living in the BEN affected environment.