Pattern of Hepatitis A Incidence According to Area Characteristics Using National Health Insurance Data

Abstract

Objectives Over the past several years, the incidence of hepatitis A infection has been increasing rapidly in the young-adult population in Korea. We examined the effects of area-level socioeconomic status and environmental hygiene on the incidence of hepatitis A. Methods This study is based on the registered national population of Korea and the national health insurance data from 2004 to 2008. A total of 73 459 individuals were confirmed to have had hepatitis A. The standardized incidences of hepatitis A in 232 districts adjusted for sex and age of people were calculated for each year, and the rate ratios of the incidence rates were estimated according to area-level socioeconomic status and environmental hygiene using multiple Poisson regression models. Results The incidence rates of hepatitis A infection were 15.6 (per 100 000) in 2004, 19.0 (per 100 000) in 2005, 27.2 (per 100 000) in 2006, 25.1 (per 100 000) in 2007, and 61.7 (per 100 000) in 2008. The analysis of the area-level effects showed that residential areas of the less deprived than other regions, areas with higher levels of education, and heavily populated areas were significantly associated with increased risk. Conclusions There is a very strong possibility that both area-level socioeconomic status and environmental hygiene play a role in increasing the risk of hepatitis A infection in Korea. Therefore, to reduce hepatitis A infection, we need a nationwide strategy that considers these area-level characteristics.

Age-period-cohort analysis of hepatitis A incidence rates in Korea from 2002 to 2012

“…For example, the per capita Korean gross domestic product remained at <200 USD between the Korean War (1950-1953) and 1968, although it has subsequently increased to approximately 27,000 USD in 2015. This economic development and concomitant improvements in public sanitation have altered the epidemiology of hepatitis A in Korea, and the endemicity of hepatitis A has changed from high to intermediate [10]. In this context, various studies have evaluated the incidence, seroprevalence, risk factors, and vaccination status for hepatitis A [3,4,11-15], and have reported high incidence rates among individuals who are 20-39 years old.…”

“…The cause of this spike in incidence is thought to be cases of sporadic occurrences in many regions, as observed in 2008 in the Gwangju region by Seo et al [10] and an increase in laboratory diagnoses due to the rapid growth of awareness of hepatitis A.…”

“…Various factors have likely influenced these effects. For example, these dramatic changes are closely related to the economic development of Korea, which was relatively weak until 1970, until which point Korea was characterized by poor public health, sanitation, and individual hygiene [10]. Thus, cohorts from this period likely had anti-HAV antibodies because they were exposed to HAV during their childhood [12].…”

“…In contrast, subsequent socioeconomic and sanitation improvements likely delayed HAV exposure in the post-1980 cohorts [11,13]. Nevertheless, a risk of exposure is still present, as Korean public sanitation has not yet improved to the level of advanced countries that have low HAV endemicity [10]. …”

“…First, we were not able to determine the incidence of asymptomatic infections [10], as many children have subclinical symptoms of hepatitis A, and it is possible that we underestimated the incidence of hepatitis A in this age group. Second, we only evaluated data from an 11-year period, which is relatively short.…”