Issued April, 1996
Among persons less than 15 years of age, hepatitis A remained the most frequent of the types reported; hepatitis B and NANB hepatitis were reported in small numbers of persons in this age-group (Table 2). The percentage of NANB hepatitis cases among patients 60 years old and older (8.8%) was the highest of the three types. However, most persons who acquire any type of viral hepatitis are between the ages of 20 and 39: approximately 45% of hepatitis A, 63% of hepatitis B, and 61% of NANB hepatitis are reported among persons in this age span.
From 1992 to 1993, the number of hepatitis A cases among patients 20-39 years of age decreased 10%; hepatitis B cases, 21%; and NANB hepatitis cases, 19%. Demographic factors for all types showed patterns consistent with those of previous years (Table 2).
In 1989, Hispanic patients accounted for 9% of reported hepatitis A cases. While this percentage increased to 12% by 1993, the absolute number of Hispanic cases declined, as was true for other racial/ethnic groups. When the percentages of Hispanic cases were examined for both old reporting forms and newly revised forms for the 1990 data, there was no evidence that the coding of ethnicity separately from race affected reporting of such cases.
Analysis of Risk Factor Data
The analysis of epidemiologic data for 1993 took into consideration the changes in both incidence and reporting practices. Reporting was analyzed by groups of states to determine if significant biases existed in the data when reports from all participating states were included for analysis. Criteria for good reporting states ("core" states) included adequate serologic testing of reported cases (at least 80% of reported cases tested for IgM anti-HAV or HBsAg), and reporting to the VHSP of a high proportion of cases reported to NNDSS (at least 50% of total cases reported to NNDSS also reported to VHSP). In addition, core states were further subdivided into those with rates above the national average for each type, and those with rates below the national average, and comparisons were made between these subgroups. Trends in these core states were then compared to trends in the remaining states for evidence of consistency and potential bias.
For hepatitis A, analysis of the core group of states showed that trends were very similar between the core states and all reporting states, and between the high-rate and low-rate subgroups. In the trend analyses that follow, hepatitis A risk factors were based on reported cases from all reporting states, and trends were analyzed by using absolute numbers of cases. For hepatitis B and C/NANB, a core group of 15 states were selected using the same reporting criteria and high levels of serologic testing for HBV during 1983-1993. These states accounted for approximately 30% of all cases of hepatitis B reported to the VHSP in this period.
For hepatitis B and C/NANB hepatitis, artifactual changes in reporting levels resulted in significant differences between the trends for all VHSP states and the trends in the core states, although there were no differences between high- and low-incidence states. For hepatitis B and hepatitis C/NANB hepatitis, trends in risk factors were analyzed by using absolute numbers of cases from the core states only.
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