Is the recent increase in the reported cases of hepatitis C / NANB a real increase?
Am J Infect Control. 1996 Oct;24(5):415-6.

Introduction

The numbers of hepatitis C and non-A, non-B (NANB) hepatitis cases reported in the United States have fluctuated dramatically in the last 5 years, particularly since tests for antibody to hepatitis C virus (anti-HCV) were introduced in 1990. In addition, the reported incidence of this disease has varied considerably between different surveillance systems (Table 1). The incidence of hepatitis C reported to the National Electronic Telecommunications System for Surveillance (NETSS) declined moderately from 1985 to 1990, but then increased by almost 130% from 1990 to 1992. The incidence rate in 1994 was still 73% higher than its 1990 level. In contrast, the incidence of hepatitis C in the Sentinel Counties Study of Acute Viral Hepatitis (1), which was initially 4-fold higher than the NETSS reported incidence, declined by 80% from 1989 through 1984. A similar decline was also observed in cases reported to the Viral Hepatitis Surveillance Program (VHSP). Possible reasons for these discrepancies include the widespread use of new diagnostic tests in laboratory-based reporting. The increase in cases reported to NETSS may have been the result of laboratory reports of chronically infected patients, or anti-HCV positive patients identified through screening programs. To better determine the reasons for these changes in nationwide reporting, during July-August of 1995 the Hepatitis Branch conducted a survey of a sample of county health departments to determine their practices and policies with regard to the reporting of hepatitis C and NANB hepatitis cases.

Methods

Counties were selected as a stratified random sample of those counties that had reported at least one case of hepatitis C/NANB in 1993. The selection list consisted of 790 such counties, and a 20% sample of 161 counties was selected. Stratification of the sample by population size ensured that large counties would have a high probability of selection.

Each county health department was asked to complete a questionnaire that covered seven categories: reporting sources of data, case definitions, laboratory reporting, follow-up for incomplete case reports, resources for surveillance, uses to which data were put, and information on respondents.

Results

The data presented here are based on a preliminary analysis of the first 90 questionnaires that were returned. This represented an early response rate of 56%. In a preliminary analysis comparing county health departments that had or had not responded, no differences were found in population size or geographic location. Respondents included public health nurses and epidemiologists. About half of the respondents had worked at the health department for more than 10 years.

Respondents cited hospitals (34%) as the most common source of case reports prior to 1991; laboratories were next (20%). From 1991 to the present, they cited laboratories as the most common source of case reports (53%); hospitals were second (30%). Physicians were cited as the third most common reporting source in each period. Blood banks and other sources were cited with similar rankings in each period.

Nearly half of the health departments surveyed did not apply published case definition criteria when reporting acute hepatitis C/NANB cases. Fifty-six percent of respondents said that a case would be reported as hepatitis C/NANB on the basis of a physician’s diagnosis alone. Forty-nine percent said that they accepted cases on the basis of laboratory reports alone. Discrete dates of onset of symptoms were required by only 36% of respondents, and exclusion of hepatitis A and B was required by 40% of respondents.

A large percentage of respondents said they followed up on incomplete case reports; however, 39% of these respondents also stated that they would accept and report a case on the basis of a laboratory report alone. When asked how they obtained the information required to provide an accurate diagnosis, 96% of respondents said they contacted the physician who made the report. Sixty-eight percent did follow-up that included contacting the patient. Only 39% determined if supplemental testing was done on specimens that were reported positive for anti-HCV.

Among the 23% of respondents who did not do follow-up on incomplete case reports, 52% said other public health problems took priority, while 50% cited lack of personnel. Thirty-six percent cited the lack of any effective intervention for hepatitis C/NANB patients as a reason.

Eighty-five percent of respondents reported increases in the number of cases reported during the past 5 years, mostly owing to laboratory reporting of anti-HCV positivity without evidence of acute disease. Only 12% cited a true increase in the disease incidence in their county or jurisdiction.

When asked to cite actions taken by the county health department in response to reported cases of hepatitis C/NANB, 77% of respondents said they provided counseling to patients. Thirty percent said they published newsletters containing data on hepatitis C/NANB.

We asked respondents to suggest ways that CDC could improve reporting of hepatitis C/NANB. Most pronounced was an expression of confusion regarding what should be done with case reports of persons with chronic hepatitis C/NANB. Many respondents felt that CDC should publish a clearer, updated case definition. Many also wanted guidelines from CDC for follow-up of incomplete case reports. Respondents suggested that CDC create educational programs targeting health-care workers in an effort to increase the reporting of diseases to the county health departments.

Summary

Since testing for anti-HCV became widely available, county health departments have increasingly relied on laboratories as sources of case reports for hepatitis C/NANB. This has resulted in an artifactual increase in the reported incidence of hepatitis C because of the reporting of anti-HCV-positive persons with no clinical or epidemiologic evidence of acute disease. Physician-reported cases continue to be a small proportion of all reported hepatitis C/NANB cases. In addition, many county health departments confirmed that they pass these laboratory test positive results on to the state health departments without sufficient confirmation of acute disease. Primarily because of lack of personnel and other diseases being seen as higher priority, county health departments do not attempt to obtain additional information necessary to confirm acute disease.

Further analysis of the survey results is being conducted. Issues to be examined include the purpose of surveillance of viral hepatitis; the importance of focusing on acute, symptomatic disease to determine true incidence; and the need for separate surveillance systems to monitor patients with chronic infections and chronic liver disease. Such surveillance efforts in the future will depend on strict adherence to case definitions, and on adequate resources to support them.

References

1. Alter MJ, Mast, EE. The epidemiology of viral hepatitis in the United States. Gastroenterology Clinics of North America 1994;23:437-455.