By Liz Highleyman

People of Asian and Pacific Islander descent have a relatively high rate of hepatitis B virus (HBV) infection, since the disease is endemic in much of Asia. In these areas, people were often infected at birth before the widespread availability of the hepatitis B vaccine. While a majority of people infected as adults spontaneously clear the virus, 90% of those infected as infants develop chronic disease.

There has not been much research, however, on differences in prevalence between first-generation Asian immigrants to the U.S. and their children and grandchildren, an issue addressed by Michele Tana and colleagues from California Pacific Medical Center at the Digestive Disease Week (DDW 2009) annual meeting last week in Chicago.

Chronic hepatitis B affects approximately 400 million people worldwide, with a disproportionately high prevalence in Asians and Pacific Islanders, the researchers noted as background. It is estimated that 1 in 10 Asian/Pacific Islanders is chronically infected with HBV.

Guidelines put forth by various organizations lack consistency regarding HBV screening of Asian/Pacific Islanders, they continued. While many research groups recommend screening of all Asian/Pacific Islanders for chronic HBV -- and this has been mandated by recent legislation in Congress -- the U.S. Centers for Disease Control and Prevention (CDC) and the American Association for the Study of Liver Diseases (AASLD) each have slightly different guidelines.

As part of the San Francisco Hep B Free campaign, the investigators offered free HBV serological screening -- and vaccination, if appropriate -- to more than 2000 Asian/Pacific Islanders between January and October 2008.

Results

	Of the 2118 total participants screened, 72 (3.4%) were chronically infected with HBV.
	Among people who reported previous HBV vaccination, 90 (32.5%) were found to lack protective antibodies and 3 (1.1%) were chronically infected.
	Among the Asian/Pacific Islanders screened, 64 (3.3%) were chronically infected with HBV.
	Men were 1.5 times more likely than women to be chronically infected.
	Adults aged 60 years or older were 3 times more likely to be infected compared with younger individuals.
	Asian/Pacific Islanders born in endemic regions were 4.6 times more likely to be chronically infected than U.S.-born Asian/Pacific Islanders.
	Among Asian/Pacific Islander participants who were not chronically infected, 993 (51%) lacked protective antibodies and therefore were at risk for future HBV infection.

In an earlier study, a Markov model of different screening strategies suggested that it is cost-effective to screen all Asian/Pacific Islanders for chronic HBV, regardless of birthplace, the researchers noted. But few studies have examined rates of chronic infection in second- and third-generation Asian/Pacific Islanders -- that is, people born in the U.S. whose parents or grandparents were born in Asia.

Based on an interim analysis of the Hep B Free Campaign, the investigators hypothesized that "it is not cost-effective to screen all Asian/Pacific Islanders given the lower prevalence rates in second- and third-generation U.S.-born Asian/Pacific Islanders."

"Clearly, there is a need for identification of hepatitis B cases in the Asian/Pacific Islander community and vaccination when appropriate," they concluded. "By identifying non-traditional risk factors such as parental birthplace in U.S.-born Asian/Pacific Islanders, we hope to make screening efforts more targeted, cost-effective, and successful."

Transplant Hepatology, California Pacific Medical Center, San Francisco, CA.

6/12/09

Reference
M Tana, K Hoda, J Wong, and others. HBV Screening in Asian Pacific Islander Americans: An Interim Analysis of the Hep B Free Program. Digestive Disease Week (DDW 2009). Chicago. May 30-June 4, 2009. Abstract W1811.