Coinfection

More Than 2 Million People Worldwide Are Coinfected with HIV and Hepatitis C

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Approximately 2.3 million people are living with both HIV and hepatitis C virus (HCV), about half of whom are people who inject drugs, according to a meta-analysis of nearly 800 studies published in the February 24 advance online edition of The Lancet. The analysis found that the overall likelihood of people with HIV being coinfected with HCV is about 6%, but good data are lacking for many countries.

HIV and HCV are both blood-borne viruses that are transmitted in similar ways. HCV is a heartier virus that can live longer on surfaces and in equipment used to inject drugs, while HIV is more easily transmitted through sex.

Worldwide there are approximately 37 million people living with HIV and 115 million people with antibodies to hepatitis C, indicating either past or present infection. It is well known that many people are coinfected with both viruses, but precise estimates have been hard to come by.

Lucy Platt from the London School of Hygiene and Tropical Medicine and colleagues performed a systematic review and meta-analysis to get a better estimate of the number of people with HIV/HCV coinfection.

The study was sponsored by the World Health Organization (WHO), which commissioned it to inform an update of its guidelines on coinfection screening and initiation of antiretroviral therapy (ART), and to inform regional and national strategies for HCV screening and management, according to a press release from the University of Bristol.

The study authors searched medical databases including MEDLINE, Embase, CINAHL+, POPLINE, Africa-wide Information, Global Health, Web of Science, the Cochrane Library, and WHO databases, looking for studies published between January 2002 and January 2015 that measured the prevalence of HIV and HCV. Out of 31,767 citations identified, 783 studies met the inclusion criteria, resulting in 902 estimates of the prevalence of HIV/HCV coinfection.

Included studies had HIV population sample sizes of more than 50 individuals and recruited participants based on HIV infection status or other behavioral characteristics. Editorials or reviews containing no primary data, samples of HCV or HIV/HCV coinfected individuals, samples relying on self-reported infection status, and samples drawn from populations with other comorbidities or interventions that put them at increased risk of coinfection were excluded.

Populations were categorized according to HIV exposure, and the regional burden of HIV/HCV coinfection was derived by applying coinfection prevalence estimates to published numbers of HIV-positive individuals. The researchers then did a meta-analysis to estimate the odds of HCV infection among HIV-positive compared to HIV-negative people.

Results

  • Among HIV-positive individuals the likelihood of HIV/HCV coinfection was:

o   2.4% for general population samples;

o   4.0% for pregnant women or people exposed through heterosexual contact;

o   6.4% for men who have sex with men;

o   82.4% for people who inject drugs.

  • Taking into account the relative sizes of these populations, the overall coinfection prevalence among HIV-positive people was estimated at 6.2%, with an interquartile range (IQR) of 3.4% to 11.9%.
  • The odds of HCV infection were 5.8 times higher for people living with HIV compared to their HIV-negative counterparts.
  • Worldwide, the researchers estimated there are approximately 2,278,400 HIV/HCV coinfected people (IQR 1,271,300 to 4,417,000).
  • Of these, just over half, or 1,362,700 (IQR 847,700 to 1,381,800), are people who inject drugs.
  • Eastern Europe and Central Asia contributed most to this total -- an estimated 607,700 cases (IQR 404,100 to 746,500) or 27% -- due to their high concentration of injection drug users.
  • Sub-Saharan Africa also accounted for a large number of cases -- 429,600 (IQR 199,100 to 2,155,900) or 19% of the total -- due to its high HIV burden. 

"We noted a consistently higher HCV prevalence in HIV-infected individuals than HIV-negative individuals across all risk groups and regions, but especially in [people who inject drugs]," the study authors concluded. "Targeted and outreach approaches are needed for [people who inject drugs] and [men who have sex with men] because stigmatization and other factors might limit their access to services for testing and treatment."

"The study shows that not only are people with HIV at much higher risk of HCV infection, groups such as people who inject drugs have extremely high prevalence of HCV infection -- over 80%," Philippa Easterbrook of WHO’s Global Hepatitis Program said in the University of Bristol press release. "There is a need to scale-up routine testing to diagnose HCV infection in HIV programs worldwide, especially among high-risk groups, as the first step towards accessing the new, highly curative HCV treatments."

"This study shows how important injecting drug use is in driving the epidemic of HCV in people with HIV infection, especially in eastern European and Central Asian countries," added Peter Vickermanfrom the University of Bristol. "It also shows the need to scale up prevention interventions, such as needle and syringe programs and opioid substitution therapy, as well as access to HIV and HCV treatment, to reduce morbidity and new infections."

As for limitations, Graham Cooke and Timothy Hallett from Imperial College London noted in an accompanying commentary that the confidence intervals of the estimates are wide, reflecting "the paucity of high quality data from population studies."

"Despite a systematic search of published and unpublished literature, estimates were identified in only 45% of countries and the study quality was variable," lead author Platt acknowledged in the release. "Improvement in the surveillance of HCV and HIV is imperative to help define the epidemiology of coinfection and inform appropriate policies for testing, prevention, care and treatment to those in need."

In addition, the estimates rely on HCV antibody status, and some people infected with hepatitis C clear the virus, either naturally or with treatment. The most commonly cited figure for the proportion of people who spontaneously clear HCV is around 25%, and somewhat lower for people with HIV, but Cooke and Hallet noted that studies from high burden HIV populations suggest that perhaps only half of people with HCV antibodies currently have detectable HCV viral load and therefore could benefit from treatment.

While the coinfected population is a small proportion of all people with hepatitis C worldwide -- probably less than 5% -- it may account for a greater proportion of individuals with HCV-attributable morbidity and mortality, Cooke and Hallet suggested. Targeting the HIV/HCV coinfected population "could be an initial way to begin the…wider scale-up of HCV treatment."

"As well as being highly effective with cure rates of more than 90%, new interferon-free treatments are almost as effective in patients with HIV and relatively easy to give with ART," Cooke and Hallet concluded. In addition to using the infrastructure of HIV programs to treat HIV/HCV coinfected individuals, "the global community needs to leverage and emulate the wider success of the AIDS response to ensure greater access to HCV treatment for all."

3/23/16

References

L Platt, P Easterbrook, E Gower, et al. Prevalence and burden of HCV co-infection in people living with HIV: a global systematic review and meta-analysis. The Lancet. February 24, 2016 (online ahead of print).

GS Cooke and TB Hallett. HCV and HIV: shared challenges, shared solutions (comment). The Lancet. February 24, 2016 (online ahead of print).

Other Source

University of Bristol. More Than Two Million People Are Co-Infected with HIV and Hepatitis C. Press release. March 8, 2016.