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IHRC 2015: Opioid Substitution Therapy, Especially with Needle Exchange, Reduces Hepatitis C Transmission


A pooled analysis of 25 studies has for the first time shown good evidence that methadone and other forms of opioid substitution therapy substantially reduce new hepatitis C virus (HCV) infections, according to a report presented today at the 24th International Harm Reduction Conference in Kuala Lumpur, Malaysia. Previously, this had been clearly demonstrated for HIV, but not hepatitis C.

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While an independent effect of needle and syringe exchange on hepatitis C was not demonstrated, programs which combined opioid substitution therapy with needle and syringe exchange were more effective, reported Lucy Platt of the London School of Hygiene and Tropical Medicine.

In most settings, the proportion of people who inject drugs who have hepatitis C is far higher than the proportion who have HIV. Furthermore, HCV is readily transmissible in miniscule quantities and for several weeks outside the body. The combination of these factors makes hepatitis C harder to keep under control than HIV.

Two previous systematic reviews on the topic did not demonstrate that needle and syringe program and opioid substitution therapy (OST) were effective in preventing the spread of hepatitis C. However, the new systematic review and meta-analysis is able to take account of several studies published in the past few years and also deal with some methodological problems of previous reviews.

The data from all relevant studies which met pre-determined quality criteria were included. Of note, these were all observational studies -- mostly prospective cohorts, but also some cross-sectional and case-control studies. In total, 25 studies were included, mostly from the US, Canada, the UK, and Australia, plus a few from other European countries.

Opioid substitution therapy supplies users of an illegal drug such as heroin with a replacement drug -- such as methadone or buprenorphine -- under medical supervision. This helps the person reduce the frequency of injection and reduces their dependence on illegal drugs.

This analysis compared rates of new HCV infections among people who currently, or had recently, received opioid substitution therapy with rates among people who did not get OST.

There were 1089 new HCV infections in the studies, with over 4262 person-years of follow up. Individuals receiving OST had a 39% lower risk of acquiring hepatitis C (rate ratio 0.61).

The results did not vary according to characteristics of the study participants, such as experience of prison, homelessness, or frequency of injecting. On the other hand, studies with a lot of female participants showed OST to be somewhat less effective.

In sensitivity analyses which excluded studies with a weaker methodology or a greater risk of bias, the results showed OST to be even more effective. Further, there was no evidence of publication bias (a tendency of researchers only to publish encouraging findings).

Next, the researchers looked at new HCV infections among people who did or did not have high coverage in needle and syringe programs -- in other words, having enough sterile equipment for every injection or regularly using a needle exchange program. In studies assessing this, there were 641 new HCV infections over 1015 person-years of follow-up.

Here, the evidence was weaker and was not statistically significant (rate ratio 0.83). There was considerable variation between studies, with European studies more likely to show effectiveness.

But analysis of people who received both opioid substitution therapy and high coverage in needle and syringe programs showed that HCV infections were reduced by 71%, and this was statistically significant (rate ratio 0.29). Results were consistent in sensitivity analyses.

"In summary, there is strong evidence that opiate substitution therapy reduces HCV transmission," concluded Platt.



L Platt et al. Effectiveness of needle/syringe programmes and opiate substitution therapy in preventing HCV transmission among people who inject drugs. 24th International Harm Reduction Conference. Kuala Lumpur, Malaysia, October 18-21, 2015.