PRO: Needle Exchange Programs Should Be Instituted to Reduce Hepatitis C Virus Transmission

Abbreviations

AOR

adjusted odds ratio

HCV

hepatitis C virus

HIV

human immunodeficiency virus

NEP

needle exchange program

OST

opiate substitution therapy

PWID

person who injects drugs

Key Points

• Needle exchange programs (NEPs) reduce risk behavior, transmission of hepatitis C virus (HCV), and health care costs.

• NEPs help identify people with hepatitis C and provide important linkage to opiate substitution therapy (OST) and direct‐acting antiviral therapies.

• NEPs are vital to any hepatitis C elimination strategy.

Heroin use has increased dramatically over the past decade, with more than 500,000 heroin users estimated in the United States today. Injection drug use is the primary route of HCV transmission, with a 75% HCV antibody prevalence rate observed in people who inject drugs (PWID). Injection risk behaviors, such as the sharing of contaminated needles and equipment, contribute significantly to viral transmission.1 NEPs providing free access to sterile needles and safe disposal of used units have existed since the early 1990s. Most NEPs also offer sterile injection equipment as well as a linkage to other health care services. Based on available data, NEPs are an effective means to reduce injection risk behavior, HCV transmission, and health care cost and are a vital component for all HCV elimination strategies (Table 1).

Table 1.

Summary of Evidence Proving That NEPs Should Be Introduced to Reduce HCV Transmission in PWID

Statement	Evidence
NEPs reduce injection risk behavior	NEP participants: Share fewer needles: AOR 0.77 (0.67‐0.88),1 AOR 2.0 (versus 3.2),12 AOR 0.3 (0.2‐0.5)3 Share fewer cookers: AOR 2.0 (versus 2.6),12 AOR 0.39 (0.3‐0.6)3 Share fewer filters: AOR 1.1 (versus 1.6)12
NEPs reduce HCV transmission	High‐coverage NEPs reduced: HCV transmission by 52% in a meta‐analysis of more than 900 patients4 HCV transmission by 76% in a meta‐analysis of 2497 patients5 HCV prevalence by 29% in New York City7
NEPs reduce costs	Using full harm reduction (high‐coverage NEP + OST) to decrease HCV prevalence by 90% by 2030: Averts 70 treatments per 1000 PWID8

Reduction in Risk Behavior

One analysis from four US cities revealed that participants in NEPs were less likely to share needles, with an adjusted odds ratio (AOR) of 0.77 (range 0.67‐0.88) compared with nonparticipants.1 A subsequent US study reaffirmed these findings, showing NEP participants share fewer needles (AOR 0.3 [0.2‐0.5]) and cookers (AOR 0.39 [0.3‐0.6]).2

Reduction of HCV Transmission

There is conclusive evidence that NEPs reduce transmission of human immunodeficiency virus (HIV), with a meta‐analysis of more than 6000 patients showing a 58% risk reduction in NEP participants.3 In the highly publicized example of Scott County, Indiana, state‐supported high‐coverage (100% of injections covered by a sterile needle) NEPs initiated in response to an HIV epidemic among PWID led to a dramatic reduction in incident HIV cases after just 3 months.4 Because HIV is transmitted through similar mechanisms as HCV, it is not surprising to see similar reductions when HCV was studied specifically. A meta‐analysis from the United Kingdom consisting of more than 900 patients showed a 52% reduction in HCV transmission after institution of high‐coverage NEPs.5 Moreover, a recently published Cochrane review showed a 76% reduction in HCV transmission with high‐coverage NEPs in 2497 patients in the United Kingdom, with the larger of these studies estimating that 1400 HCV cases were averted as a result of NEPs.6 Population‐level data have also shown the effectiveness of NEPs in reducing HCV transmission, with a study showing a 29% reduction in HCV prevalence among PWID in New York City after NEP introduction.7

Reduction of Health Care Costs

NEPs are also important for reducing the cost to society of HCV eradication. A recently published model of the required HCV treatment rate to decrease prevalence by 90% revealed that full harm reduction averts 70 treatments per 1000 PWID.8 Based on current costs of direct‐acting antiviral therapy in the United States, this translates to approximately $2 million to $6.7 million in savings annually per 1000 PWID. This projected model also takes into account the important concept of HCV reinfection after successful treatment, with the 5‐year reinfection rate of 10% to 15%. It is clear that there are important cost‐saving opportunities while reducing HCV transmission through the use of NEPs.

Additional Benefits of NEPs

Not only do NEPs reduce HCV transmission, they also provide important linkage to screening, support (e.g., case workers), and treatment. As such, they identify patients with HCV who otherwise would go undiagnosed and untreated. As an example, PWID who were assigned case workers within a week of NEP participation were 87% more likely to pursue treatment in a randomized trial from Baltimore, Maryland.9 Full harm reduction combining high‐coverage NEPs in tandem with OST has been shown to strengthen the effect of reducing HCV transmission by 79%, compared with 52% with high‐coverage NEP alone.5

Limitations of Available Data

The preceding paragraphs have outlined firm evidence that NEPs reduce HCV transmission. However, the impact of NEPs on HCV transmission is difficult to measure due to a challenging patient population and the plethora of factors that influence risk behavior that are not easily controlled in observational studies; thus, some studies have failed to demonstrate a positive effect. It is important to remember that individual studies on this topic are retrospective in design because it would be an unethical violation of beneficence to randomize people away from the potentially beneficial intervention of NEPs. For this reason, they are frequently combined into meta‐analyses that show conflicting evidence on the impact of NEPs in reducing HCV transmission, particularly in North America.10, 11 Many of the inconsistencies in the data can be explained by confounding, misclassification of the intervention exposure, and bias.

Confounding exists because of inadequate control for important covariables influencing HCV transmission, such as frequency of injection, duration and type of injection drug use, baseline injection risk behavior, homelessness, and high‐risk sexual practices. In one meta‐analysis, only half of the studies controlled for any confounders in their data.10 Misclassification of the intervention exposure has also been widespread, with many studies failing to standardize for the intervention of interest: high‐coverage NEPs. For example, one meta‐analysis showed that NEPs have no effect or may even increase HCV transmission.10 Unfortunately, none of the included studies required high‐coverage NEPs (≥100% of injections covered by a clean syringe), and only one mandated weekly attendance. Bias has been another concern in these studies, including volunteer/selection bias, dilution bias (non‐NEP users obtaining clean syringes from elsewhere in the community), and information bias (self‐reporting). These issues are what have produced the significant heterogeneity and large inconsistency reported, and they stem from important between‐study differences in enrollment, definition of the intervention, and outcome assessed. The results should be interpreted with caution, and it highlights the need for further well‐designed research. For example, studies from the United Kingdom that applied careful inclusion criteria and made efforts to mitigate confounders clearly show that high‐coverage NEPs reduce HCV transmission.

Conclusion

NEPs are the first and arguably the most important pillar of any HCV elimination strategy. NEPs reduce injection risk behavior and HCV transmission and provide vital linkage to OST and direct‐acting antiviral therapies. For maximum effectiveness, NEPs should be combined with opioid addiction treatment. In addition, NEPs reduce the overall costs involved in HCV elimination. Therefore, high‐coverage NEPs should be introduced to reduce HCV transmission.

Potential conflict of interest

Nothing to report.