Wide variation in estimates of global prevalence and burden of chronic hepatitis B and C infection cited in published literature.

To evaluate the extent of heterogeneity in global estimates of chronic hepatitis B (HBV) and C (HCV) cited in the published literature, we undertook a systematic review of the published literature. We identified articles from 2010 to 2014 that had cited global estimates for at least one of ten indicators [prevalence and numbers infected with HBV, HCV, HIV-HBV or HIV-HCV co-infection, and mortality (number of deaths annually) for HBV and HCV]. Overall, 488 articles were retrieved: 239 articles cited a HBV-related global estimate [prevalence (n = 12), number infected (n = 193) and number of annual deaths (n = 82)]; 280 articles had HCV-related global estimates [prevalence (n = 86), number infected (n = 203) and number of annual deaths (n = 31)]; 31 had estimates on both HBV and HCV; 54 had HIV-HBV co-infection estimates [prevalence (n = 42) and number co-infected (n = 12)]; and 68 had estimates for HIV-HCV co-infection [prevalence (n = 40) and number co-infected (n = 28)]. There was considerable heterogeneity in the estimates cited and also a lack of consistency in the terminology used. Although 40% of 488 articles cited WHO as the source of the estimate, many of these were from outdated or secondary sources. Our findings highlight the importance of clear and consistent communication from WHO and other global health agencies on current consensus estimates of hepatitis B and C burden and prevalence, the need for standardisation in their citation, and for regular updates.