MONTREAL — The escalating numbers of new and existing hepatitis C infections in Canada are reinforcing the evidence of a U.S. epidemic, Dr. Robert P. Myers said at Canadian Digestive Diseases Week.
“The burden of hepatitis C has grown dramatically in the past decade,” said Dr. Myers of the University of Calgary (Alta). “It is vital that we continue with preventive measures and maximize treatment.”
By using an administrative hospitalization database from the Calgary Health Region, Dr. Myers identified 4,002 hospitalizations related to hepatitis C virus (HCV) infection between 1994 and 2004, 22% of which (869 cases) were HCV liver-related, he reported. Among this group of patients, 67% were male, with a median age of 50 years.
With a concentration on number of hospitalizations, length of hospital stay, and in-hospital mortality, Dr. Myers documented an approximate fourfold increase over the 11-year period. Hospital charges for this population also increased an average of 41% between 2000 and 2004, which was attributable to more admissions rather than longer hospital stays. The length of stay actually stabilized during this period, at an average of 7 days, he said.
“We project if this rate continues in a linear fashion that by 2020, across Canada, about $240 million [Canadian] will be spent on hepatitis C liver-related hospitalizations,” he said.
Patient subgroups that were identified as particularly high risk included females, who represented 25% of the hospitalizations at the beginning of the study period but increased to 35% by the end, for an average annual increase of 19%.
“Interestingly, if you compare that to the males, somewhat counterintuitively males had a lower annual growth rate in hospitalizations of 13.1%,” he said. “The etiology of that is a bit unclear, but it may perhaps be due to underreporting at the beginning of the study.” He noted that even when adjustments were made to account for underreporting, the findings remained significant.
Other high-risk groups were patients aged 40–59 years, for whom hospitalizations increased more than in any other age group, at 19% annually, and HIV-coinfected patients. The latter accounted for about 1% of hospitalizations at baseline, but made up 6% of hospitalizations by the end of the study, he said.
Dr. Myers noted that recent projections about the burden of HCV in the United States are very similar to his findings. According to a calculation model based on epidemiologic data from the U.S. Centers for Disease Control and Prevention, mortality related to HCV is likely to increase over the next 25 years (J. Viral Hepat. 2007;14:107–15). The study estimated that the number of cases has risen from about 3,700 in 1998, and will peak at about 13,000 in 2030. Similar Canadian projections have been reported.
A separate study reported at the meeting was based on a unique, province-wide data system to estimate the rate of new cases of HCV infection in British Columbia. The British Columbia Centre for Disease Control laboratory data from 1992–2005 enable the researchers to document positive HCV results in people who previously tested negative, said Margot Kuo, Ph.D., from the University of British Columbia, Vancouver. As such, it offers a unique picture of testing practices and seroconversion trends.
Her analysis identified a significantly higher incidence of newly acquired infection than had been previously reported, with the highest incidence in 20- to 29-year-olds and 30- to 39-year-olds at 13.6 and 11.3 cases per 100,000, respectively.
“The effect of gender on the rates was not consistent across all ages,” she noted. “Males had a slightly higher incidence across all age groups except teens. We were picking up HCV seroconversion among teen females four times more frequently than among teen males.” This was reflected in an incidence of 5 cases per 100,000 in teen females, compared with 1.3 cases per 100,000 in teen males.
“While this could mean that teen females are at higher risk, it's likely related to testing patterns,” she commented. “Teen males have a very low rate of testing and display very low repeat test behavior, while females tend to test more, and have more repeat tests.” Nevertheless, the finding has important implications for the development of prevention strategies, she said.