HCV Infection Burden Among People Who Inject Drugs Varies By Country

An international research study designed to estimate the global, regional, and national prevalence of hepatitis C virus (HCV) infection among people who inject drugs (PWID) has determined that nearly 40% (39.2%) of recent injection drug users are living with HCV. According to the study authors, the data on HCV infection burden produced by the study could assist World Health Organization (WHO) efforts to eliminate HCV as a "global public health threat by 2030," allowing for more accurate monitoring and targeting of prevention/treatment strategies.

The estimates were completed using 2015 data from 2 previously published systematic reviews. The first systematic review provided an estimate of global, regional, and national prevalence of injection drug users between the ages of 15 and 64 and the prevalence of HIV, HCV, and hepatitis B virus (HBV) infections among those with recent (within the previous year) injection drug use. The second review estimated global, regional, and national prevalence of viraemic HCV overall.

Statistical analysis of the data collected from the 2 systematic reviews showed that only 98 of 206 countries worldwide (48%) "had available data on HCV antibody prevalence among people with recent injecting drug use (n = 374 studies)" and only 19 countries worldwide (9%) "had available data on HCV RNA prevalence among people with recent injecting drug use (n = 32 studies),” according to the study authors.

According to the study authors, because of the paucity of data on the prevalence of HCV RNA, the investigators were required to estimate the HCV viraemic proportion of those living with HCV infection. The completed this by, “using estimates of the prevalence of HCV antibodies among people with recent injecting drug use within each country and multiplying by an estimate of the proportion developing viraemic HCV infection.”

The investigators were able to collect sufficient data to enable estimates of HCV prevalence among PWID, and the number of individuals living with HCV overall for 98 countries. This enabled the team to estimate the population of individuals with recent injection drug use living with HCV in 76 countries worldwide, and to enable estimates of "the population of people with recent injecting drug use as a proportion of all people living with HCV" in 55 countries worldwide,” the study authors wrote.

Data showed that among the 71.1 million individuals with HCV infection worldwide, 8.5% (6.1 million [95% uncertainty interval (UI) 3.4‐9.2]) of those infections occurred among individuals with recent injection drug use.

Variations in regional and national prevalence of HCV among injection drug users were seen as well, with the highest estimates of HCV viraemic prevalence on a regional basis occurring in Eastern Europe at 48.6% (1,466,500 individuals), and in the Caribbean where prevalence of HCV viraemic infection among individuals with recent injection drug use is estimated at 46.4% (37,500 individuals). Sub-Saharan Africa saw the lowest prevalence of HCV viraemic infection among people with recent injection drug use, at 16.3 % (225,000 individuals).

In North America the prevalence of HCV viraemic infection among individuals with recent drug use topped out at over 40% (40.5%, UI 29.2, 51.7) with prevalence at an estimated 52.9% (UI 44.5, 61.2) in Canada, and 39.8% (UI 28.4, 51.3) in the United States.

Globally, the small island nation of the Republic of Mauritius, had the highest estimated prevalence of HCV viraemic infection among individuals with recent drug use at 72.8% (UI 68.8, 76.7; 5000 individuals).

“These findings highlight countries and regions where a focus on HCV prevention and treatment among people with recent injecting drug use will be required if HCV elimination targets are to be met,” wrote Jason Grebely, PhD, an associate professor with The Kirby Institute at the University of New South Wales in Sydney, lead author of the study, and colleagues. “Half of all people with recent injecting drug use living with HCV are from just 4 countries: the Russian Federation, the United States, China, and Brazil."

Using these new estimates, the WHO and other health service organizations can allocate resources for harm reduction measures, testing, treatment, and prevention according to the epidemiology of specific countries and territories. The accurate estimates produced by this study, according to the authors, “are crucial to guide policy and practice and guide the development of strategies to enhance testing, linkage to care and treatment in this population” and suggest that “strategies to achieve a reduction in HCV burden will need to be tailored to the individual country, based on the HCV epidemiology and the proportion of overall infections occurring in people with recent injecting drug use."

The study, “Global, regional, and country-level estimates of hepatitis C infection among people who have recently injected drugs,” was published in Addiction.