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drinkanddrugsnews
| June 2013
Harm reduction |
Syringes
www.drinkanddrugsnews.com
DeaD or
Can reducing the ‘dead space’
in injecting equipment save
lives, asks
Jamie Bridge
F
or the more than 100,000 people who inject drugs in the UK, needle
and syringe programmes have proven invaluable since their official
adoption by the mid-1980s Conservative government. These services
have helped to avert an HIV epidemic among this population – with HIV
rates now consistently below 2 per cent among current and former
injectors nationwide – and a huge international body of evidence has been
developed to demonstrate how these services can reduce not only risk behaviours
and HIV transmission, but injecting frequency and returns of used equipment. They
also enable referrals to drug treatment and save public money, hence their adoption
in 86 countries around the world and their inclusion in the UK
Drug strategy 2010
.
The impact on viral hepatitis, however, has been much more modest – around half
of all people who inject drugs in the UK may be infected with hepatitis C, with little
change since 2001. This reflects the fact that the hepatitis C virus is more easily
transmissible than HIV, and so requires even higher coverage levels for prevention
services. According to the Health Protection Agency (HPA), 57 per cent of people who
inject drugs in England receive enough needles to cover every injection, yet a quarter
of current injectors aged under 25 still reported needle and syringe sharing.
Emerging evidence, however, suggests that the design of the needles and
syringes themselves could help to further reduce HIV and hepatitis C transmission
– depending on how much ‘dead space’ they contain.
Every syringe inevitably retains some fluid when its plunger is fully depressed,
in what is known as the dead space. As the diagram shows, some types of syringe
will contain more of this dead space than others. ‘High dead space’ syringes with
detachable needles will retain fluid in the tip of the syringe, the hub of the needle
and the needle shaft itself. In ‘low dead space’ designs with permanently attached
needles – such as the 1ml insulin needles used by many people who inject drugs
– fluid is only retained in the needle shaft.
The difference can be up to 40 times more fluid being retained in high dead
space syringes compared to low dead space ones. In laboratory experiments that
simulated common injection practices, low dead space syringes retained up to
1,000 times less blood than high dead space syringes, so if a person shares a low
dead space syringe with someone living with HIV there will be less blood retained in
the syringe and therefore less viral load and a lower risk of transmission.
Modelling work by Dr William Zule and colleagues in the USA has helped to
quantify what this could mean in the real world. Their results suggest that injection-
related HIV epidemics could be stabilised, reversed or avoided altogether when the
majority of people who inject drugs use low dead space syringes. Laboratory studies
have also shown that the hepatitis C virus can survive for up to 60 days in high dead
space syringes, compared to just one day in low dead space alternatives – hence
the inclusion of low dead space syringes in the latest World Health Organization
guidance on viral hepatitis prevention among people who inject drugs.
More research is needed, particularly to assess how effective low dead space
syringes can be in the real world, rather than in models and laboratories. But it is an
area of great promise. Provided it is managed carefully, the transition from high dead
space to low dead space syringes is also a risk-free intervention for services to
provide as part of a comprehensive harm reduction package. It must never be a
substitute for the highest possible coverage of harm reduction services, but rather a
complementary string to the bow to make these programmes even more effective.
Crucially, a shift from high dead space to low dead space syringes should never
be forced upon someone. People who inject drugs may prefer a wide range of
different syringes and needles and this needs to be respected. In particular, 1ml
insulin syringes with fixed needles – which often have the lowest dead space –