Hospital stays for hepatitis B or C virus infection or primary liver cancer among immigrants: a census-linked population-based cohort study

Abstract

A lthough primary liver cancer (the majority of which is hepatocellular carcinoma) is uncommon in Canada, representing about 1% of all cancers, its incidence has increased threefold since the early 1980s.1,2 Much of this increase has been attributed to a higher proportion of immigrants from countries endemic for the hepatitis B virus (HBV) and, to a lesser extent, the hepatitis C virus (HCV). [3][4][5][6][7] Globally, chronic infection with HBV or HCV, or both, is the underlying cause in about 80% of cases of hepatocellular carcinoma and, therefore, also primary liver cancer. Although HBV and HCV are both blood-borne, the infections have distinct epidemiologic features and risk factors. The seroprevalance of HBV in Canada was estimated to be as low as less than 0.5% in a population-based household survey sample, 9 whereas about 3% of new immigrants are chronically infected with the virus. 10 In patients with chronic HBV infection, the lifetime risk of dying from liver cirrhosis or liver cancer is about 15% to 25%.11,12 Canada also has a low prevalence of chronic HCV infection (about 0.7%). 13 For both HBV and HCV, there may be underascertainment of prevalence.14,15 Risk factors for HBV infection include sexual contact, intravenous drug use and vertical transmission (e.g., from mother to baby), 16 whereas most newly identified HCV infections occur among injection drug users and infected immigrants from HCV-endemic countries. Background: The recent increase in the incidence of primary liver cancer in Canada has been attributed to a higher proportion of immigrants from countries endemic for hepatitis B virus (HBV) and hepatitis C virus (HCV). We examined hospital discharges for liver disease in Canada, focusing on those for all liver-related diseases, HBV infection, HCV infection and primary liver cancer, by 3 immigration-related variables: immigration status, duration of residence in Canada and risk level of the source country.

Differing profiles of people diagnosed with acute and chronic hepatitis B virus infection in British Columbia, Canada

“…In general, the asymptomatic nature of HBV infection leads to late diagnosis after complications have developed[ 1 ]. Studies have shown that immigrants in Canada are disproportionately affected by HCC and decompensated cirrhosis and have up to 5 times greater risk of death from these causes than their Canadian-born counterparts[ 14 , 30 , 31 ]. Therefore, screening for HBV within the East Asian population is vital for early diagnosis.…”

“…This may have resulted in the misclassification of East Asians from the Philippines as Whites and in the underestimation of the HBV in East Asian population. Previous studies have shown that foreign-born and Indigenous Canadians have a higher prevalence of chronic HBV relative to Canadian-born and non-Indigenous Canadians, respectively[ 5 , 30 , 38 ]. Similar findings have been reported in Australia and the United States[ 10 , 39 ].…”