Acute hepatitis B infection and hepatitis B surface antigen positivity reported in the Department of Veterans Affairs: Occurrence in a population seeking medical assistance

Military Medicine, Jun 2003 by Kralovic, Stephen M, Danko, Linda H, Simbartl, Loretta A, Roselle, Gary A

In the United States, reported acute hepatitis B infections steadily declined from 18,003 cases in 1991 to 8,036 cases in 2000. Despite this decline, hepatitis B is a significant concern to the Veterans Health Administration (VHA) of the Department of Veterans Affairs because of the need for care of veterans afflicted with this disease and the VHA health care workers at risk for occupational exposure to hepatitis B virus. On an annual basis from federal fiscal year (FY) 1991 through FY 2001. the VHA Infectious Diseases Program Office requested information from patient care sites regarding hepatitis B. The reported number of patients with acute hepatitis B ranged from 446 to 749 during this period. This translates into a case rate per 100,000 veterans served of 29.15 and 12.68 for FYs 1991 and 2001, respectively. The number of persons with a positive hepatitis B surface antigen test during this 11-year period ranged from 2,688 to 3,100, suggesting a sizeable pool from which occupational exposure may occur. The rate of decline in the cases of acute hepatitis B in the VHA is more than that seen nationally in the United States.

Introduction

Hepatitis B virus (HBV] is a significant human viral pathogen that is estimated to infect at least 300,000 new persons each year in the United States.1-3 Many of those newly infected will have minimal or no symptomatology and will clear the infection without seeking medical attention.1 An estimated 0.1 to 0.3% percent will develop a fulminate course of disease.3 Most persons, regardless of severity of illness, will resolve their disease process. However, up to 10% will progress to chronic or persistent infection that may lead to long-term medical difficulties, including end-stage liver disease.4,5 Because humans are the only natural host for the hepatitis B virus, this long-standing persistence, along with the variable time of infectivity for the 90% with HBV infection that does resolve, serves as a source from which new infections may occur. There are estimated to be 1 to 1.25 million chronic carriers of hepatitis B in the United States with up to 25% of these having chronic, active disease.6,7 The direct medical cost for both acute and chronic disease is substantial, while indirect costs are difficult to evaluate.8 Those populations with acute disease or the chronic carrier state who seek medical attention serve as a pool of risk from which health care workers may occupationally acquire hepatitis B infection.9 The advent of the Occupational Safety and Health Administration (OSHA) Blood-Borne Pathogens Standard allows easier access for employees to immunization for this vaccine-preventable infection;10 however, not all at-risk employees accept the offer of vaccination and a small percentage of those accepting vaccine do not achieve immunity. Efforts to quantify risk may encourage further vaccine acceptance by employees. Further, assessment of occurrences of both acute disease and the chronic carriers helps to delineate at-risk populations on which to focus education and vaccination programs.

We have assessed the occurrence of reported, acute HBV infection in a population that seeks medical attention and also to obtain some indicators of the potential risk pool to health care workers delivering care to this group. This has been accomplished in the Department of Veterans Affairs (DVA)-Veterans Health Administration (VHA), one of the largest health care providers in the United States; VHA had more than 35 million outpatient visits and more than 565,000 inpatient discharges on more than 4.06 million unique persons served by the VHA during fiscal year (FY) 2001.

Materials and Methods

Through the VHA Central Office Infectious Diseases Program Office, the DVA conducts an annual Infectious Diseases/Infection Control census of VHA medical facilities (167) within the United States, Puerto Rico, and the Philippines. Data from the annual census are not specific to just inpatient encounters. The annual census instrument is electronically transmitted to each of those VHA medical facilities. Requested data from the previous FY (October 1 through September 30) is electronically transmitted to a central database after the initial request. With regard to hepatitis B, the census instrument contained the following two information points, verbatim: 1) Report the total number of patients (not tests) who tested positive for Hepatitis B surface antigen (HBsAg ) during FY [ ], and 2) Report the number of confirmed, acute cases of Hepatitis B (excluding chronic carriers) during FY [ ].

The number of unique patients served by VHA facilities was obtained from query of the inpatient and outpatient treatment files of the VA data repository at the Austin Automation Center. Final query for numbers presented was made on July 1, 2002. Data for national statistics used for comparative purposes were obtained from the Centers for Disease Control and Prevention (CDC) and the U.S. Census Bureau.11-22 Case rates for VHA data were determined using a denominator of persons served by the VHA (i.e., seeking medical assistance). Case rates from the CDC were determined using the total U.S. population as the denominator; age- and male gender-specific case rates for the U.S. population were also determined.