Recent incarceration increases HIV and hepatitis C risk for people who inject drugs

Michael Carter
Published: 12 November 2018

People who inject drugs (PWID) recently released from prison or jail have a substantially increased risk of acquiring infection with HIV or hepatitis C virus (HCV), according to the results of a systematic review and meta-analysis published in The Lancet Infectious Diseases. Recent incarceration was associated with an 81% increase in the risk of HIV and 62% increase in the risk of hepatitis C.

“Our findings suggest that incarceration is an important enhancer of HIV and HCV acquisition risk among PWID globally,” comment the authors. They believe their findings have important policy implications, especially the decriminalisation of illicit drug use. They also believe new interventions are needed to minimise HIV and HCV risk among PWID, including better linkage of people recently released from prison to harm reduction and opioid substitution services.

It has been estimated that 58% of PWID will experience incarceration. The period immediately following release from incarceration is believed to be a time of high risk for HIV and HCV transmission as well as opioid-related overdose, due to relapse to drug use after release. Several studies have suggested that incarceration of PWID could be an important contributor to the ongoing epidemics of HIV and HCV among this population, but the extent of the association between incarceration and HIV and HCV acquisition among PWID is poorly understood. This prompted an international team of investigators to conduct a systematic review and meta-analysis of research addressing this question.

The researchers identified 41 studies (21 unpublished) addressing this question. All were conducted between 2000 and 2017. Study locations were Australia, Canada, Czech Republic, France, Greece, India, Ireland, Mexico, Spain, Thailand, UK and USA.

Recent incarceration was defined as release from prison or jail in the past three, six, or 12 months or since last follow-up. Data were also examined on the impact on past incarceration and risk of HIV and HCV acquisition.

A total of 14 studies reported on the effect of recent incarceration on HIV acquisition risk. The pooled results showed that recent incarceration was associated with an 81% increase in HIV acquisition risks (RR = 1.81; 95% CI, 1.40-2.34, p < 0.001). Recent incarceration continued to be associated with increased HIV risk after controlling for potential confounders (RR = 1.48; 95% CI, 1.16-1.90, p = 0.002) and also in studies assessed to have a low-to-moderate risk of bias (RR = 1.65; 95% CI, 1.26-2.16, p = 0.006).

A further 12 studies reported in the impact of past incarceration and HIV acquisition, showing a non-significant 25% increase in risk (RR = 1.25; 95% CI, 0.94-1.65).

The effect of recent or past incarceration on HIV acquisition risk did not differ by geographical region or country income level. The effect of incarceration was greater among younger than older participants.

The effect of recent incarceration on HCV acquisition risk was assessed in 18 studies. These showed that recent incarceration was associated with a 62% increase in the risk of acquiring HCV infection (RR = 1.62; 95% CI, 1.28-2.05, p < 0.001). The finding was essentially unchanged after controlling for confounders (RR = 1.60; 95% CI, 1.21-2.11, p < 0.009).

The impact of past incarceration on HCV acquisition was examined in 22 studies, showing a significant 21% increase in risk (RR = 1.21; 95% CI, 1.02-1.43, p = 0.027). However, this finding was not significant after controlling for confounders; nor was there a significant association in studies rated as having low-to-moderate risk of bias.

As with HIV, the association between incarceration and increased HCV acquisition risk did not differ between geographical region or country income level. However, there was a greater effect in countries with higher rates of incarceration.

“To our knowledge, this study is the first to have quantitatively synthesised available evidence on the effect of incarceration on HIV and HCV acquisition risk among PWID,” write the authors.

“Our findings are consistent with studies that find that incarceration is associated with relapse to injecting drug use and that recently incarcerated PWID exhibit increased injecting risk behaviour and reduced access to harm reduction interventions compared with PWID who do not report recent incarceration.”

The authors believe their findings have several important implications for public health and international drug policies:

  • Current international policy has a punitive approach to PWID, leading to high rates of incarceration.
  • A need for improved prison-based harm reduction, which is absent in most countries and often inadequate even when available.
  • A requirement for improved linkage on release from incarceration to harm reduction and other services to address the numerous social vulnerabilities, especially homelessness, that are increased for PWID on release from incarceration.

“Our findings add to the growing body of evidence for the harms associated with international drug policy, which result in many people who use drugs being incarcerated, and support calls for decriminalisation of illicit drug use and greater access to prison-based harm reduction, with linkage following release," comment the authors. "However, it is likely that addressing many of the multiple social vulnerabilities experienced by PWID will also be required to fully reduce the risks associated with incarceration.”


Stone J et al. Incarceration history risk of HIV and hepatitis C virus acquisition among people who inject drugs: a systematic review and meta-analysis. Lancet Infect Dis, online edition,

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