[Prevalence of anti-HCV antibodies among adults in Poland--results of cross-sectional study in general population].
According to WHO data, there are 130-170 million hepatitis C virus (HCV) infected persons world-wide. Data on the prevalence of HCV infection in Poland is still insufficient. The aim of study was to determine the prevalence of HCV infection in the general population in Poland and to characterize the positive predictive value of the ELISA screening test. A total of 4822 persons aged 18+ and hospitalized on surgical, trauma-orthopedic and laryngological wards in Lubelskie, Mazowieckie, Swietokrzyskie, Warminsko-Mazurskie and Wielkopolskie voivodeships were enrolled into the study. The scheme of cluster sampling was applied. Hospitals wards were selected randomly from Health Care Units Registers. Detection of anti-HCV antibodies was performed using the 4th generation qualitative ELISA test (Dia Sorin, Murex). All positives samples were subject to further testing by Western Blot and retested by ELISA. According to ELISA test producers instructions, samples that were repeatedly reactive were considered as positive (reactive). Using the confirmation test (Western Blot), antibodies directed against specific antigens of HCV (C1, C2, E2, NS3, NS4, NS5) were determined. To determine the prevalence of HCV infections, repeatedly reactive ELISA samples, confirmed by Western Blot (WB) were used. In order to estimate the prevalence of anti-HCV antibodies in general population, indirect standardization according to age groups (<30, 30-49, 50-69, >or =70), gender and place of residence (urban/rural) was employed. Initially positive ELISA test results were obtained in 92/4822 patients (1.91%) and repeatedly positive results--in 46/4822 patients (0.95%). The presence of anti-HCV was confirmed by WB in 54/4822 (1.12%), which constituted 58.7% (54/92) of single-reactive samples and 95.7% (44/46) of double-reactive samples. The positive results of Western Blot were obtained for 10 samples, which were not repeatedly reactive in ELISA test. The standardized prevalence of anti-HCV antibodies amounted to 0.86% (95% CI: 0.59-1.14%). Positive predictive value for a single reactive ELISA test accounted for 47.8% (95% CI: 37.4-58.2%). Given the low predictive value of the single-positive ELISA, performance of repeated ELISA tests, even for epidemiological purpose, would be recommended.