GARY A. ROSELLE, M. D.
PROGRAM DIRECTOR FOR INFECTIOUS DISEASES
VETERANS HEALTH ADMINISTRATION
DEPARTMENT OF VETERANS AFFAIRS
SUBCOMMITTEE ON BENEFITS
COMMITTEE ON VETERANS' AFFAIRS
U.S. HOUSE OF REPRESENTATIVES
April 13, 2000
Thank you for the opportunity to provide data regarding veterans testing positive for hepatitis C in the VHA. In order to interpret the data that I will present it is necessary to very briefly describe how the data were collected with a comment about the meaning of the test data.
The data were collected from VA’s Emerging Pathogens Initiative, an automated electronic surveillance system that is in place throughout the VA nationally. Once a positive hepatitis C virus antibody laboratory test is found by the local computer system, a variety of other data are automatically extracted, particularly demographic data such as age, gender, and era of service. Demographic data for all persons served by the VHA during fiscal years 1998 and 1999 were extracted from the VHA data set located at the Austin Automation Center in Texas. The information provided today will include data on persons who were hepatitis C virus antibody positive at the time of testing during fiscal years 1998 and 1999, and data on the total patient population served by the VHA over the same time interval.
The hepatitis C virus antibody test used is designed to screen patient serum for the presence of antibody to the hepatitis C virus. A positive test result does not mean that an individual patient has active hepatitis, but, as with all antibody tests, it defines the response of the individual person to infection with the virus. As with all tests, false positive and false negative results can occur. The likelihood that a positive test for hepatitis C virus antibody is truly positive is directly related to the number of people in the population who have the disease. When testing for cause, meaning there is evidence of possible liver disease, in the VHA population served, it is very likely that the majority of the positive hepatitis C virus antibody tests are true positives. However, some patients are tested for a variety of reasons, including at their own request, despite lack of identifiable risk factors. It should also be noted that hepatitis C virus antibody tests can be intermittently positive, particularly in persons who have relatively low levels of antibody.
Now I will provide some data that covers the two year period. For this 24 month period, there was an opportunity for each reporting site to provide data 24 times since data was transmitted monthly. For FY 98 and FY 99, 92.12% of these total possible months were actually in the data set. This is remarkable provision of data for any surveillance system.
For the 24 months, 54,682 unique persons in the VHA had a positive test for hepatitis C virus antibody. I use the words "unique persons" to define actual individuals with a positive antibody test and not just number of individuals having a positive test, since a single person could have been tested more than once.
In graph 1, the age distribution revealed an average age of slightly greater than 49 years old with a rather narrow standard deviation of approximately 9.4 years. This indicates that, for the most part, the age group of persons with hepatitis C virus antibodies were clustered closely around the mean age of 49. As seen in Graph 2, when looking at gender of these persons with a positive hepatitis C virus antibody test and reporting gender, 96.4%, were male, and 3.6%, were female.
Era of service is illustrated in graph 3. Of the total number of persons who were hepatitis C antibody positive and reported an era of service, 62.7% were noted to be from the Vietnam era. The second most frequent group is listed as post-Vietnam at 18.2%, followed by 4.8% Korean conflict, 4.3% post-Korean conflict, 4.2% from WWII, and 2.7% Persian Gulf era veterans.
For comparison, it is worthwhile to look at the demographic data for all the unique persons served by the VHA during fiscal years 1998 and 1999, since this describes the population from which the persons with hepatitis C virus antibody were a subgroup.
There was a total of 4,186,667 unique persons in this data set. Graph 4 depicts the age distribution and shows the expected two peaks, one at approximately 50 years old and the other at approximately 75 years old. These would account for the groups of Vietnam and WWII era veterans. For comparison, the average age of the persons with hepatitis C virus antibody was slightly greater than 49 years.
With regard to gender, graph 5 shows that for the same two year period there were approximately 89% male and about 11% female in the total population served. In persons with tests that were positive for hepatitis C virus antibody, 96% were male.
For era served over the two year period seen in graph 6, 27.7% were Vietnam era veterans with 22.9% being WWII era veterans. This is consistent with the age distribution that was seen previously in Graph 4. Each of the remaining eras provided small percentages of the total patient population seen.
Lastly, using the Student’s t-test for age and chi-square test for gender and era statistical comparisons can be made between the persons who were found to be hepatitis C virus antibody positive and the overall population served by the VHA over the same time period. Persons who were hepatitis C virus antibody positive were statistically more likely to be younger, at age 49.4 compared to age 56.6 in the overall population served. The hepatitis C antibody positive group was also significantly more likely to be male at 96.4% compared to 89.1% in the population served. The hepatitis C antibody positive group was also significantly more likely to be from the Vietnam era of service, at 62.7%, compared to the 27.7% found in the overall population served during the two years of the review.
Thank you for the opportunity to provide these data. I will be pleased to respond the questions from the committee.