.

Incarceration is likely to increase HIV and HCV transmission among people who inject drugs, new study finds

29 October 2018

Injecting drug use, through the sharing of needles, syringes and other injecting equipment, is a primary route of transmission for both HIV and hepatitis C virus (HCV), blood-borne infections that cause considerable morbidity and mortality worldwide. New research led by the University of Bristol has found among people who inject drugs, that recent incarceration was associated with an 81 per cent and 62 per cent increase in HIV and HCV acquisition risk, respectively.

Prison bars

The study, published in The Lancet Infectious Diseases, is the first systematic review and meta-analysis to assess whether incarceration history, either recent incarceration or past incarceration, raises the risk of HIV or HCV infection among people who inject drugs. 

Through a systematic search of MEDLINE, Embase and PsycINFO databases and contacting authors of incidence studies not presenting on outcomes of interest, the research team identified 41 studies (21 of which were unpublished) with available data on these outcomes to be included in meta-analyses. 

The researchers found strong evidence that recent incarceration is associated with an 81 per cent and 62 per cent increase in the risk of HIV and HCV acquisition, respectively. These findings were robust to sensitivity analyses, including the exclusion of studies at high risk of bias. 

Jack Stone, Senior Research Associate in Health Infectious Disease Mathematical Modelling in the Bristol Medical School: Population Health Sciences and NIHR Health Protection Research Unit in Evaluation of Interventions, said: “This is the first global systematic review of quantitative studies on the effect of incarceration history on HIV and HCV transmission among people who inject drugs. Our findings provide strong evidence that recent incarceration increases HIV and HCV transmission risk. 

“We found evidence of this effect in settings where HCV transmission is known to be very low during periods of incarceration, suggesting increases in transmission risk occur following release from prison. This work is essential for understanding how incarceration, and consequently, international drug policy, can contribute to increasing the burden of HIV and HCV among people who inject drugs. Hopefully this work will help guide future evidence-based drug policies and interventions to reduce this risk.”

It is well known that people who inject drugs experience high rates of incarceration (an estimated 58 per cent have ever been incarcerated globally), with a history of incarceration frequently being associated with higher HIV and HCV infection. The period immediately following release from prison represents a high risk for relapse to illicit drug use and poses an increased risk for multiple adverse outcomes, including drug-related deaths but also increased injecting risk behaviours, homelessness and reduced access to interventions. 

Incarceration is likely to be a significant driver of HIV and HCV transmission among people who inject drugs in many settings because of the high rates of incarceration that they experience, as supported by previous mathematical modelling studies performed by this research team. 

The study has important implications for policy and public health, including:

  • international drug policy whose overwhelming focus on the criminalization of people who use drugs has led to high rates of incarceration among people who inject drugs;
  • the need for improved prison-based harm reduction which is absent in most countries and often inadequate in those in which it is provided; and 
  • the need for improved linkage upon release to harm reduction as well as other services to address many of the multiple social vulnerabilities experienced by people who inject drugs that are amplified following incarceration (including for example homelessness). 

The research team’s findings also add to the growing body of evidence for the harms associated with international drug policy and support calls for the decriminalisation of illicit drug use.

The team suggest further research is needed to better explain the factors associated with incarceration that increase HIV and HCV acquisition risk, to help the development of interventions to reduce these risks. It also unknown, whether the effects of incarceration differ by type of detention (jail or prison etc.) or length of incarceration. 

The research was funded by the Engineering and Physical Sciences Research Council (EPSRC), National Institute for Health Research (NIHR) and National Institutes of Health.

Paper: ‘Incarceration history and risk of HIV and hepatitis C virus acquisition among people who inject drugs: A systematic review and meta-analysis’ by Jack Stone et al in The Lancet Infectious Diseases. 29 October 2018.


Further information

About the National Institute for Health Research (NIHR) 

This orthopaedic study was funded by the National Institute for Health Research (NIHR) which was established by the Department of Health and Social Care to: 

  • fund high quality research to improve health
  • train and support health researchers
  • provide world-class research facilities 
  • work with the life sciences industry and charities to benefit all
  • involves patients and the public at every step

For further information, visit the NIHR website www.nihr.ac.uk

About the Engineering and Physical Sciences Research Council (EPSRC)

As the main funding agency for engineering and physical sciences research, our vision is for the UK to be the best place in the world to Research, Discover and Innovate.

By investing £800 million a year in research and postgraduate training, we are building the knowledge and skills base needed to address the scientific and technological challenges facing the nation. Our portfolio covers a vast range of fields from healthcare technologies to structural engineering, manufacturing to mathematics, advanced materials to chemistry. The research we fund has impact across all sectors. It provides a platform for future economic development in the UK and improvements for everyone's health, lifestyle and culture.

We work collectively with our partners and other Research Councils on issues of common concern via Research Councils UK. www.epsrc.ac.uk

About the National Institutes of Health (NIH) 

NIH, the nation's medical research agency, includes 27 Institutes and Centers and is a component of the US Department of Health and Human Services. NIH is the primary federal agency conducting and supporting basic, clinical, and translational medical research, and is investigating the causes, treatments, and cures for both common and rare diseases. For more information about NIH and its programs, visit www.nih.gov.