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- Original Article Cohort study on the asymptomatic chronic carrier rate of hepatitis B virus among male adults in Korea
- Byung Joo Park, Yoon Ok Ahn
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Epidemiol Health 1989;11(2):263-273
DOI: https://doi.org/
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Abstract
In Korea, the rates of hepatitis B virus (HBV) infection and hepatocellular carcinoma (HCC) incidence, a major risk factor for which is HBV infection, are among the highest in the world. Therefore, in order to establish strategies for the prevention of HBV infection and HCC, the natural history of HBV infection should be urgently investigated; in particular, it is important to estimate the rate of asymptomatic chronic HBV infections, because individuals with such infections are considered at risk of chronic liver diseases such as HCC. In order to identify the prevalence of chronic HBV infections among adult males, 1495 individuals without any abnormal findings during their regular physical checkup in 1986 were randomly selected from the population insured by the Korea Medical Insurance Corporation. Radioimmunoassay (RIA) tests were performed on the subjects to detect the serological markers of HBV; namely, hepatitis B surface antigen (HBsAg), antibody to the hepatitis B surface antigen (anti-HBs) and antibody to the hepatitis B core antigen (anti-HBc), and direct interviews were conducted to determine participants’ history of hepatitis B vaccination. Of these subjects, 624 healthy males who were found to be nonvaccinees were selected and followed up for 2 years. In 1988, re-tests of the three serological markers of the hepatitis B virus using RIA testing, as well as physical checkups including liver function tests, were performed. The final study population of 370 adult males consisted of those who had no abnormal findings in either physical checkups, had not been vaccinated against HBV, and received a re-test of the serological markers of HBV after the follow-up period. The point prevalence rate of HBsAg among the 370 men enrolled was 9.6% (95% confidence interval [CI]=6.6-12.6), and after the 2-year follow-up period, the rate increased to a significantly higher level (13.0%; 95% CI=9.6-16.6). The rate of asymptomatic chronic carriers whose HBsAg tests continued to be positive during the 2-year follow-up period was 6.2% (95% CI=3.7-8.7), corresponding to 60% of the point prevalence at the time of enrollment. The age-adjusted chronic carrier rate calculated using males 20-59 years of age from the 1985 Nationwide Population and Housing Census data as a standard population was 6.2%(95% CI=6.19-6.21). The asymptomatic chronic carrier rates by age group were 6.8%in their 20s and 30s, 5.6%in their 40s, and 4.3%in their 50s; a decreasing trend according to age was found, but it was not statistically significant. The number of asymptomatic chronic carriers in Korea as of 1985 was estimated to be around 1.3 million men between their 20s and 50s. The serological profiles of the HBV markers suggested frequent loss and acquisition of the serological markers during the 2 years. While the prevalence of susceptible decreased from 14.1% at the time of enrollment to 12.7% at the end of the 2-year follow-up, the prevalence of HBsAg increased significantly. Thus, studies more precisely elucidating the mechanisms underlying these patterns in serological profiles are needed
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