Hepatitis B clearance rare, and even rarer among Asians

Last Updated: 2016-07-14

By Anne Harding

NEW YORK (Reuters Health) - Patients seropositive for hepatitis B surface antigen (HBsAg) are more likely to clear the virus if they are non-Asian, male, older than 45, and have lower levels of HBV DNA, according to a large new study in a "real-world" U.S. cohort.

HBsAg seroclearance was rare, the researchers found, at 0.31% per year. "It's much lower than many studies of selected populations have recorded, so physicians need to be realistic with their patients when we initiate treatment or give them counseling about treatment," Dr. Mindie Nguyen of Stanford University Medical Center, Palo Alto, California, told Reuters Health in a telephone interview. The findings were published online July 1 in Alimentary Pharmacology and Therapeutics.

People positive for HBsAg are at increased risk of cirrhosis, and can develop hepatocellular carcinoma even in the absence of cirrhosis, Dr. Nguyen noted. Studies have suggested that HBsAg clearance is rare, and may be less frequent in Asian populations, but investigators have not compared Western and Asian populations head-to-head.

In the new study, Dr. Nguyen and her team looked at 4,737 patients with chronic hepatitis B (CHB) from five primary care, gastroenterology and multispecialty centers, as well as one university medical center. Patients were retrospectively enrolled between 2001 and 2014. Ninety-five percent were Asian, and none had been treated with interferon.

Follow-up lasted a median 32 months. Over 16,844 person-years, 52 patients had HBsAg seroclearance, for an annual rate of 0.31% and an overall rate of 1.2%. Predictors of seroclearance were non-Asian ethnicity (hazard ratio 2.8, p=0.02), male sex (HR 2.1, p=0.03) and age older than 45 years (HR 1.8, p=0.04). Patients who had baseline HBV DNA levels above 10,000 IU/mL were half as likely to clear the virus as patients with lower HBV DNA levels.

There was no significant difference in clearance rates between the 11% of patients who had received treatment and the rest of the study participants.

Asian patients probably have a more difficult time clearing the virus than Western patients because they typically acquire the virus in infancy or early childhood, Dr. Nguyen noted. This almost never occurs in the U.S., because babies born to hepatitis B-infected mothers receive immunoglobulin to clear the infection, and hepatitis B immunization is now universal, she added. U.S. patients are prone to contract the virus in their teen or young adult years, Dr. Nguyen explained, when their immune systems are more mature and they are more able to fight off the infection. Also, she added, Westerners are more likely to be infected with genotype A hepatitis B, which responds more readily to treatment.

Currently, interferon is the most effective treatment for chronic hepatitis B infection, but the drug is very rarely used in the United States, Dr. Nguyen noted. First-line treatments are the oral medications entecavir and tenofovir, which are less effective than interferon but have fewer side effects.

Better treatments are urgently needed, Dr. Nguyen said. "It's a very active area of research, and I hope this will fuel it even further."

The National Institutes of Health and the Digestive Disease Research Foundation supported this research. Three coauthors reported disclosures.

SOURCE: http://bit.ly/29AMs7q

Aliment Pharmacol Ther 2016.