[MPH] Emma Davidson 2007
Abstract
Background
End stage liver disease (ESLD), including chronic liver disease (CLD) and hepatocellular carcinoma (HCC), is a global public health problem causing considerable morbidity, mortality and health care expenditure. Hepatitis B (HBV) and C (HCV) are preventable infections which cause ESLD and thereby are significant contributors to this burden of disease.
Aim
This research aimed to describe the prevalence and population attributable risk percent (PAR%) of HBV and HCV among CLD decedents between 1998 and 2002 in New Zealand. The PAR% represents the proportion of disease that could be prevented if these infections were eliminated. The contribution of this study was to update the existing research (1992-1997), which was used as a baseline, and to allow the examination of any trends over time in the contribution of these infections to CLD deaths.
Methods
The study sample was selected from CLD deaths between 1998 and 2002. Data were extracted from medical records to determine the decedent's HBV and HCV status. Prevalence and PAR% were estimated separately for the four major ethnic groups. There was deliberate over-sampling of the Maori and Pacific Island populations to ensure that the prevalence data were meaningful. The baseline study of CLD deaths was adjusted to allow direct comparison of its results with those of the present study.
Results
Data were extracted for 241 of the 369 decedents selected for inclusion. Hepatitis B and C test results were identified in 75% and 63% respectively of the decedents with data extracted. Among those tested, the prevalence (and estimated PAR%) of HBV surface antigen (HBsAg) were 38% (36%), 33% (31%), 60% (59%) and 3.6% (3.4%) for Maori, Pacific Island, Asian and European decedents respectively. Among those tested, the prevalence (and estimated PAR%) of HCV infection was 17% (16%), 0% (0%), 25% (23%) and 14% (13%) for Maori, Pacific Island, Asian and European decedents respectively.
In the adjusted baseline study, HBV and HCV test results were identified in 65% and 39% respectively of the decedents with data extracted. Among those tested, the prevalence (and estimated PAR%) of HBsAg were 56% (53%), 75% (71%), 100% (99%) and 12% (11%) for Maori, Pacific Island, Asian and European decedents respectively. Among those tested, the prevalence (and estimated PAR%) of HCV infection was 14% (14%), 0% (0%), 0% (0%) and 14% (13%) for Maori, Pacific Island, Asian and European decedents respectively.
Conclusions
HBV and HCV infections remain important contributors to CLD mortality in New Zealand. An apparent increase was shown in HCV testing since the baseline study. The prevalence and PAR% of acute HBV infection in CLD deaths appears to have decreased since the baseline study, but the prevalence and PAR% of HCV infection in CLD deaths has remained relatively static. The difference in HBV prevalence between ethnic groups persists, with decedents of Maori, Asian and Pacific Island ethnicity carrying the greatest burden of disease. Maori decedents did not appear to have experienced the same reduction of acute HBV infection as other ethnic groups.