Characteristics of adults in the hepatitis B research network in North America reflect their country of origin and hepatitis B virus genotype

Abstract

Background & aims: Chronic hepatitis B virus (HBV) infection is an important cause of cirrhosis and hepatocellular carcinoma worldwide; populations that migrate to the United States and Canada might be affected disproportionately. The Hepatitis B Research Network (HBRN) is a cooperative network of investigators from the United States and Canada, created to facilitate clinical, therapeutic, and translational research in adults and children with hepatitis B. We describe the structure of the network and baseline characteristics of adults with hepatitis B enrolled in the network.

Methods: The HBRN collected data on the clinical characteristics of 1625 adults with chronic HBV infection who are not receiving antiviral therapy from 21 clinical centers in North America.

Results: Half of the subjects in the HBRN are men, and the median age is 42 years; 72% are Asian, 15% are black, and 11% are white; with 82% born outside of North America. The most common HBV genotype was B (39%); 74% of subjects were negative for the hepatitis B e antigen. The median serum level of HBV DNA when the study began was 3.6 log10 IU/mL; 68% of male subjects and 67% of female subjects had alanine aminotransferase levels higher than the normal range.

Conclusions: The HBRN cohort is used to address important clinical and therapeutic questions for North Americans infected with chronic HBV and to guide health policies on HBV prevention and management in North America.

Keywords: ALT; Chronic Hepatitis B Virus Infection; HBeAg; USA.

Figure 1

Map indicating location of clinical sites (blue circles, orange diamonds and green square), DCC (red balloon), Immunology Center (yellow arrowhead) comprising the HBRN and the funding agency, NIDDK (same location as NIH clinical center).

Figure 2

Organizational Structure of HBRN. The Hepatitis B Research Network (HBRN) consists of 21 clinical sites recruiting adults, a data coordinating center, an immunology center, and the Liver Disease Branch at NIDDK. A Steering Committee is responsible for study oversight. Several committees were established and an independent Data and Safety Monitoring Board (DSMB), appointed by NIDDK, reviewed the protocols and the progress of the studies.

Figure 3a

Distribution of serum ALT (categorized by upper limit of normal) by race. Serum ALT was categorized as ≤1 x ULN, >1 to 2 x ULN and >2 x ULN, with ULN defined as 30 U/L for men and 20 U/L for women.

Figure 3b

Distribution of serum HBV DNA level by race. Serum HBV DNA was categorized as <10³ IU/mL, 10³ to 10⁴ IU/ml, 10⁴ to 10⁷ IU/mL and ≥10⁷ IU/mL.

Figure 4

Distribution of phases of chronic HBV infection by race. Each slice of the pie represents the percent phenotype distribution.

Figure 5

Distribution of subjects in the HBRN Cohort Study by Continent of birth and HBV genotype. The size of each pie represents the proportion of enrollees who were born in each continent (with the exception of Europe and South America-which were enlarged slightly to facilitate viewing) and each slice of the pie represents the percent genotype distribution.