Research in context
Evidence before this study
In this systematic review and meta-analysis we searched eight databases for studies that reported the prevalence of HCV and HIV, published between Jan 01, 2002, and Jan 28, 2015, following PRISMA guidelines. The searches were done with no language restrictions on Jan 28, 2015, in MEDLINE, Embase, CINAHL+, POPLINE, Africa-wide Information, Global Health, Web of Science, and the Cochrane Library, Index Medicus of the Eastern Mediterranean Region, Index Medicus of the South-East Asian Region, LILACS, and Western Pacific Region Index Medicus. Search terms included “HIV OR Human immunodeficiency virus”, ”OR Hepatitis-C OR HCV”, and ”prevalen* OR inciden* OR seroprevalen* OR screening OR surveillance OR population* OR survey* OR epidem* OR data collection OR population sample* OR community survey* OR cohort OR cross-sectional OR longitude* OR follow-up”. Searches were tailored to each database. Reference lists were screened for additional sources.
We included studies with estimates of HCV co-infection in HIV population samples of more than 50 individuals recruited based on HIV infection status or other behavioural characteristic. We excluded editorials or reviews containing no primary data, no samples of HCV or HIV–HCV-infected individuals, or samples relying on self-reported infection status. We excluded samples drawn from populations with other comorbidities or undergoing interventions that put them at increased risk of co-infection. The search focused on published medical literature and did not include an exhaustive review of grey literature.
Previous reviews of HIV–HCV co-infection have focused on specific regions or sub-populations or have not used systematic review methods to extract and synthesise data. Data are needed to establish the global burden of HCV co-infection in HIV-infected individuals and to identify the populations at risk and the key geographical regions most affected. These data are essential to inform normative guidance and service delivery for testing and care and treatment services.
Added value of study
We estimate a midpoint of roughly 2·3 million (IQR 1·3–4·3 million) cases of HIV–HCV co-infection worldwide, of whom more than half (an estimated 1·3 million [0·89–1·4 million]) are PWID. This number equates to a worldwide HCV co-infection prevalence of 6·2% (3·4–11·9) in HIV-infected individuals. The greatest burden of HIV–HCV co-infection is in eastern Europe, where an estimated 607 700 HIV-infected people are co-infected with HCV, followed by 429 600 people in sub-Saharan Africa. Prevalence of HCV co-infection in HIV-infected people is highest in PWID (82·4%, 55·2–88·5), followed by MSM (6·4%, 3·2–10·0) and pregnant or heterosexually exposed populations (4·0%, 1·2–8·4), and lowest in general population samples (2·4%, 0·8–5·8). Odds of HCV infection are six times higher in HIV-infected people than in HIV-negative populations ranging from 1·6 times higher in the general population, 1·4–6·8 times higher in sex workers, and 4–13 times higher in MSM, PWID, and high-risk populations.
Implications of all the available evidence
Our findings clearly show that HIV-infected individuals are at high risk of HCV infection, particularly PWID who constitute 58% of the global burden of HCV co-infections in HIV-infected individuals. Routine testing of HCV in HIV-infected individuals is needed, including good linkage to care and treatment in PWID and MSM especially.
There is also a need to improve surveillance and country-level data on prevalence of HCV in all populations to help countries define their epidemiology and inform policies for hepatitis C testing, prevention, and care and treatment services.