Author information

¹Population Health Sciences, Bristol Medical School, University of Bristol, Bristol, UK; National Institute for Health Research Health Protection Research Unit in Behavioural Science and Evaluation, University of Bristol, Bristol, UK. Electronic address: adelina.artenie@bristol.ac.uk.

²Population Health Sciences, Bristol Medical School, University of Bristol, Bristol, UK; National Institute for Health Research Health Protection Research Unit in Behavioural Science and Evaluation, University of Bristol, Bristol, UK.

³Population Health Sciences, Bristol Medical School, University of Bristol, Bristol, UK; National Public Health Speciality Training Programme, South West, Bristol, UK.

⁴Yale School of Medicine, Yale University, New Haven, CT, USA.

⁵School of Medicine, University of California, San Diego, CA, USA.

⁶Centre de recherche du CHU de Québec-Université Laval, Québec City, QC, Canada; Département de médecine sociale et préventive, Université Laval, Québec City, QC, Canada; Institut national de santé publique du Québec, Québec City, QC, Canada.

⁷Department of Epidemiology, Johns Hopkins Bloomberg School of Public Health, Baltimore, MD, USA.

⁸Département de Médecine Familiale et Médecine d'Urgence, Université de Montréal, Montréal, QC, Canada; Centre Hospitalier de l'Université de Montréal Research Center, Montréal, QC, Canada.

⁹Department of Medicine, Johns Hopkins University School of Medicine, Johns Hopkins University, Baltimore, MD, USA.

¹⁰Cumming School of Medicine, University of Calgary, Calgary, AB, Canada.

¹¹Public Health and Clinical Directorate, UK Health Security Agency, London, UK.

¹²School of Public Policy, Simon Fraser University, Vancouver, BC, Canada; BC Centre on Substance Use, Vancouver, BC, Canada.

¹³Blood Safety, Hepatitis, STI and HIV Division, UK Health Security Agency, London, UK.

¹⁴BC Centre on Substance Use, Vancouver, BC, Canada; Faculty of Health Sciences, Simon Fraser University, Burnaby, BC, Canada.

¹⁵Department of Communicable Diseases, World Health Organization Regional Office for the Eastern Mediterranean, Cairo, Egypt.

¹⁶Global HIV, Hepatitis and Sexually Transmitted Infections Programmes, World Health Organization, Geneva, Switzerland.

¹⁷Cumming School of Medicine, University of Calgary, Calgary, AB, Canada; Infectious Diseases, CUPS Liver Clinic, Calgary, AB, Canada.

¹⁸Kirby Institute for Infection and Immunity, UNSW Sydney, Sydney, NSW, Australia.

¹⁹School of Health and Life Sciences, Glasgow Caledonian University, Glasgow, UK; Public Health Scotland, Glasgow, UK.

²⁰Department of Epidemiology, Johns Hopkins Bloomberg School of Public Health, Johns Hopkins University, Baltimore, MD, USA.

²¹Disease Elimination Program, Burnet Institute, Melbourne, VIC, Australia; School of Public Health and Preventive Medicine, Monash University, Melbourne, VIC, Australia; School of Population and Global Health, University of Melbourne, Melbourne, VIC, Australia.

²²Disease Elimination Program, Burnet Institute, Melbourne, VIC, Australia.

²³Disease Elimination Program, Burnet Institute, Melbourne, VIC, Australia; School of Population and Global Health, University of Melbourne, Melbourne, VIC, Australia; Department of Infectious Diseases, Public Health Service of Amsterdam, Amsterdam, Netherlands.

²⁴Population Health Sciences, Bristol Medical School, University of Bristol, Bristol, UK.

Abstract

Background: Measuring the incidence of HIV and hepatitis C virus (HCV) infection among people who inject drugs (PWID) is key to track progress towards elimination. We aimed to summarise global data on HIV and primary HCV incidence among PWID and associations with age and sex or gender.

Methods: In this systematic review and meta-analysis, we updated an existing database of HIV and HCV incidence studies among PWID by searching MEDLINE, Embase, and PsycINFO, capturing studies published between Jan 1, 2000, and Dec 12, 2022, with no language or study design restrictions. We contacted authors of identified studies for unpublished or updated data. We included studies that estimated incidence by longitudinally re-testing people at risk of infection or by using assays for recent infection. We pooled incidence and relative risk (RR; young [generally defined as ≤25 years] vs older PWID; women vs men) estimates using random-effects meta-analysis and assessed risk of bias with a modified Newcastle-Ottawa scale. This study is registered with PROSPERO, CRD42020220884.

Findings: Our updated search identified 9493 publications, of which 211 were eligible for full-text review. An additional 377 full-text records from our existing database and five records identified through cross-referencing were assessed. Including 28 unpublished records, 125 records met the inclusion criteria. We identified 64 estimates of HIV incidence (30 from high-income countries [HICs] and 34 from low-income or middle-income countries [LMICs]) and 66 estimates of HCV incidence (52 from HICs and 14 from LMICs). 41 (64%) of 64 HIV and 42 (64%) of 66 HCV estimates were from single cities rather than being multi-city or nationwide. Estimates were measured over 1987-2021 for HIV and 1992-2021 for HCV. Pooled HIV incidence was 1·7 per 100 person-years (95% CI 1·3-2·3; I²=98·4%) and pooled HCV incidence was 12·1 per 100 person-years (10·0-14·6; I²=97·2%). Young PWID had a greater risk of HIV (RR 1·5, 95% CI 1·2-1·8; I²=66·9%) and HCV (1·5, 1·3-1·8; I²=70·6%) acquisition than older PWID. Women had a greater risk of HIV (RR 1·4, 95% CI 1·1-1·6; I²=55·3%) and HCV (1·2, 1·1-1·3; I²=43·3%) acquisition than men. For both HIV and HCV, the median risk-of-bias score was 6 (IQR 6-7), indicating moderate risk.

Interpretation: Although sparse, available HIV and HCV incidence estimates offer insights into global levels of HIV and HCV transmission among PWID. Intensified efforts are needed to keep track of the HIV and HCV epidemics among PWID and to expand access to age-appropriate and gender-appropriate prevention services that serve young PWID and women who inject drugs.

Funding: Canadian Institutes of Health Research, Fonds de recherche du Québec-Santé, Canadian Network on Hepatitis C, UK National Institute for Health and Care Research, and WHO.