1998 Volume 8 Issue 5 Pages 292-296
To estimate the risk of hepatitis C virus (HCV) infection among blood donors, we conducted a retrospective cohort study with 448, 020 HCV-seronegative donors who donated blood more than once between February 1992 and July 1997 in Osaka (a total of 2, 676, 738 allogeneic blood donations). The donors were divided into four age groups according to the age at the initial donation: Group A (16-24 years), Group B (25-34 years), Group C (35-49 years) and Group D (50- 64 years). Fifty-nine donors became infected with HCV among the 448, 020 HCV-seronegative donors who donated blood more than once within a period of approximately five years. In a total of 1, 095, 668 person-years of observation (PYO), the incidence rate was 5.38 per 105 PYO, with the 95% confidence interval (95% C.I.) being 4.10 to 6.95. There was no significant difference in the incidence rate between males and females. Young donors between the ages of 16 and 24 (8.89; 95% C.I., 6.04 to 12.61) had a significantly higher incidence rate of HCV infection than donors between the ages of 35 and 49 (1.81; 0.67 to 3.95). The cumulative risk of HCV infection among donors between the ages of 16 and 64 was estimated to be 0.27% (95% C.I., 0.16 to 0.39) for males and 0.27% (95% C.I., 0.15 to 0.38) for females. Based on the recent age-specific incidence rate, the cumulative risk of HCV infection among blood donors was estimated to be about 0.3% in the Osaka district of Japan. The incidence rate differed among age groups, indicating that HCV infection is associated with age-related behaviors and the need for further epidemiological research towards the eradication of community-acquired HCV infection. J Epidemiol, 1998; 8 : 292-296.