Validity of hepatitis B and hepatitis C case definitions.

Background: Globally, an estimated 257 million people are living with chronic hepatitis B (HBV) infection and an estimated 71 million people with the chronic hepatitis C virus (HCV). The true public health dimensions and impact of hepatitis epidemics are poorly understood. Case definitions are fundamental parts of disease surveillance, representing sets of standardised criteria used to assess whether or not a person has a certain disease. The study evaluated the sensitivity and specificity of hepatitis B and hepatitis C case definitions, current at the time of data collection, recommended by the European Commission (EC) and the Centers for Disease Prevention and Control (CDC).

Methods: The study involved 150 hospital referrals with suspected cases of hepatitis from a Serbian clinic during 2014/2015. Case definitions of hepatitis B and C were tested for their sensitivity, specificity, positive and negative predictive values.

Results: EC 2008 and the CDC 2012 case definitions for acute hepatitis B, and the CDC 2012 case definition for probable case of chronic hepatitis B have low sensitivity. Case definitions which rely on laboratory confirmation only have maximal sensitivity. EC case definitions showed maximal sensitivity and specificity for hepatitis C confirmed cases. The CDC case definition for chronic hepatitis C showed low sensitivity (36.8%) and low negative predictive value (65.6%) for probable cases and maximal sensitivity and specificity for confirmed cases. Hepatitis C case definitions requiring presence of clinical criteria have low sensitivity and high specificity, resulting from presence of infection and absence of any clinical manifestation, but have high positive and negative predictive values.

Conclusion: Syndromic case definitions show low sensitivity and are of limited use. They highlight the importance of laboratory diagnostics (offering maximal sensitivity and specificity, and high positive and negative predictive values), as well as the need for universal case definitions, for confirmed cases only.