Cohort Profile: The Canadian HIV-Hepatitis C Co-infection Cohort Study

Hepatitis C virus (HCV) has emerged as one of the most vexing health problems facing HIV-infected persons. Due largely to injection drug use (IDU),430% of HIV-infected patients are co-infected with HCV in developed countries with 10 million co-infected worldwide. In 1999, 11 194 Canadians were estimated to be co-infected and this number has likely increased substantially since. HCV infection has also increasingly been reported in HIV-positive men having sex with men (MSM) who have not used injection drugs. Since the advent of highly active antiretroviral therapy (HAART) there have been dramatic reductions in morbidity and mortality from virtually all causes of illness among HIV-infected persons. One of the glaring exceptions to this trend is death from end-stage liver disease (ESLD) with rates increasing 4to 8-fold in the post-HAART era. This excess mortality may be due, in part, to improved overall survival associated with HAART, allowing competing morbidities and mortalities that were once rarely observed. In addition, HCVassociated hepatic fibrosis has been shown to progress more rapidly in the context of HIV infection, likely due to immune dysfunction. Several other factors may be at play, including chronic hepatotoxicity related to antiretrovirals, incomplete immune recovery, heavy alcohol use and problems with access and/or adherence to HAART and HCV treatment in a population with high rates of substance use. The growing burden of chronic HCV infection is expected to result in dramatic increases in the rates of cirrhosis, liver failure, hepatocellular carcinoma, transplant needs and related annual healthcare costs in Canada and worldwide. Understanding the complex interplay between sociodemographic factors, substance use, biology and treatments that may affect outcomes in co-infection is necessary to meet the challenge of providing effective