Does needle exchange work?

This article seeks to answer the question often asked by those interested in, sceptical about, and hostile to harm reduction. We also explore in some detail the wider question of the impact needle and syringe programmes can have on injecting risk.

The answer isn't, of course, completely black and white: Needle and Syringe Programmes operate in a complex social context with a community often at the margins of society, and with lots of things happening that can affect the health of drug users happening at the same time. This makes it hard to be absolutely certain that one thing has caused (or prevented) another. It also means the case that what works in one place may not be needed, or work, in another.

However, that said, the clear message from the international reviews of studies into the effectiveness of needle and syringe programmes is that they have significantly reduced behaviours which spread blood-borne disease and reduced HIV spread, without increasing the number of injectors or the frequency with which they inject (Paone 1995, Cross 1998, Heimer 1998, Monterroso 2000).

Since those judgements were made, the evidence has continued to build: in 2002 the Australian health department replicated and extended an earlier study comparing trends in HIV prevalence in cities with and without NSP.

Its conclusion was that on average HIV prevalence decreased 18% each year in cities with needle exchange programmes and increased 8% without them. An advantage so great that we can say with scientific certainty that it was, at least in part, caused by the existance of needle exchange programmes.

The same study was unable to be so definite about the impact on hepatitis C. On average NSP was associated with a fall in the prevalence of the virus in injectors of around about 2% year, significant and worthwhile but not as great as for HIV. The rate of new infections also was lower in cities with NSP, but it was still high (16% versus 25% per year) and the difference was neither large, nor statistically significant enough to confer certainty that it was caused by the presence of needle and syringe exchange schemes.

The issue of why it is so much harder to have an impact on the hepatitis C epidemic amongst injectors is discussed in our article 'injecting and risk' - to read it, click here, and also in our DVD HIV, hepatitis C and injecting drug use.

How does needle exchange reduce risk?
Needle and syringe programmes achieve their results in several ways - including through encouragement to enter opiate substitution therapy - but the main impact is to significantly reduce the need to use injecting equipment previously used by another injector.

In 2003 a US analyst combined the results of recent studies to estimate the relationship between attending NSP and infection risk behaviour. Data from 47 studies collected between 1986 and 1997 indicated that needle sharing and needle lending / borrowing consistently declined among attenders, suggesting the needle exchanges are effective in reducing risk behaviour (Sobiech 2003). The result held not only for studies which tracked attenders over time, but also for those comparing attenders with non-attenders.

Even without behaviour change, improved supply of equipment can reduce infection spread by increasing the ‘turnover’ of needles and syringes and decreasing the time used ones remain in circulation. An injector can continue to share on every injecting occasion, but if the needle they borrow has been in circulation long enough to have been used by just one or two people they are less likely to become infected than if it has been around long enough to have been used by more potentially infected individuals (Kaplan 1994, Heimer 1996, 1998).

In addition needle and syringe programmes play a key role in disseminating information and education about risk and risk avoidance to injecting drug users.

Prevalence of HIV and restricted availability of injecting equipment
In a review of studies conducted in five cities that all had a low baseline of HIV positive injecting drug users, and implemented largescale availability of sterile injecting equipment, Des Jarlais (1998) observed that the high rates of HIV seroconversion do not occur. Under these circumstances, prevalence can be stabilised or decrease.

The following are examples of cities that have experienced HIV epidemics during periods with little or no syringe distribution to injecting drug users cited by Des Jarlais.

Edinburgh:

• Early % of IDU’s tested HIV positive: 0%

• Time span to T2: 1 year

• % of IDU’s tested positive at T2: 40%

New York City:

• Early % of IDU’s tested HIV positive: 10%

• Time span to time 2 (T2): 5 years

• % of IDU’s tested HIV positive at T2: 50%

Bangkok:

• Early % of IDU’s tested HIV positive: 2%

• Time span to T2: 1 year

• % of IDU’s tested positive at T2: 40%

Manipur (India):

• Early % of IDU’s tested HIV positive: 0%

• Time span to T2: 1 year

• % of IDU’s tested positive at T2: 50%

Prevalence of HIV and wide availability of sterile injecting equipment
In contrast, HIV prevelence was contained in the following cities that implemented needle and syringe programmes, along with other harm reduction measures.

Glasgow:

• Early % of IDU’s tested HIV positive: 4%

• Time span: 6 years

• % of IDU’s tested positive: 1 %

Lund (Sweden)

• Early % of IDU’s tested HIV positive: less than 2%

• Time span: 6 years

• % of IDU’s tested positive: less than 2%

Sydney

• Early % of IDU’s tested HIV positive: 4%

• Time span: 7 years

• % of IDU’s tested positive: 4 %

Tacoma (USA)

• Early % of IDU’s tested HIV positive: 0.4%

• Time span: 5 years

• % of IDU’s tested positive: 3%

Toronto

• Early % of IDU’s tested HIV positive: 0%

• Time span: 5 years

• % of IDU’s tested positive: 2%

The effect of needle exchange in the UK
In Britain, an early harm reduction-oriented public health response to HIV, in which needle exchange was important both as a symbol (Klee 1995) is credited with helping to avert the large-scale epidemic seen in places which deny sterile injecting equipment to injectors.

In terms of the three preconditions for an HIV epidemic identified by Gerry Stimson (1996), in 1984 the UK had:

• An estimated 100,000 injecting drug users;

• A mobile injecting population in which sharing of equipment amongst single or multiple sharing partners was widespread; and

• People infected with HIV in all health regions.

This being the case, the continuing low prevalence of HIV among injectors during the 1990s represents a significant success for harm reduction interventions.

Though needle exchange is one of these, it is not the only contributor. Epidemiologists have shown that the peak and subsequent decline of incidence of HIV infection amongst injecting drug users in London occurred between 1983 and 1986 (Hickman 1995).

Interventions such as needle exchange came into being slightly after the peak, which suggests that whilst it, and associated interventions, are very likely to have assisted in the decline in incidence of HIV amongst injectors, other factors may have been involved. These other factors are likely to have included behaviour changes triggered by HIV public information campaigns reinforced by the introduction of formal needle exchange facilities staffed by individuals committed to disseminating harm reduction messages to injectors.

As the preconditions for an epidemic still exist we cannot be complacent. Stimson warned that: “the HIV epidemic has been averted, not prevented.” Given recent trends in HIV and hepatitis C prevalence, his warnings seem justified. In its examination of the British record, Drug and Alcohol Findings concluded that lack of investment in and prioritisation of harm reduction in the UK, and outmoded working methods, have left the door open to a resurgence in HIV and to rapid spread of hepatitis C (Ashton 2004).

In a seminal report on the pilot needle exchanges that were set up by the government of Margaret Thatcher, published in 1992 Gerry Stimson’s team concluded that where (as in England) there is in any event good access to injecting equipment, sharing levels are already low, and HIV infection rare, “syringe exchanges have only a limited overall effect on further reductions in syringe sharing” (Donoghoe 1992).

Later studies broadly confirmed this conclusion, the main exception being Glasgow. This may be partly because the city hosted a long term, consistent research programme (Hutchinson 2000). This was able to show that injectors who did not source needles and syringes from needle exchanges re-used after another person three times more often than exchange attenders (Frischer 1996). Had such work been done elsewhere, it might have found similar results. Importantly, despite legal restrictions Glasgow’s NSPs achieved near saturation levels of needle/syringe distribution across the entire city. Yet even here hepatitis C continued to sweep rapidly through the city’s injectors.

Elsewhere, even if there had been a protective effect, the research has not been done which could find it and/or NSP provision has been so limited that effects large enough to be detected would be unlikely. The limitations were most obvious in Scotland in legal caps on the number of needles and syringes which can be handed out at any one time but were also seen in restricted opening hours, inadequate staffing and facilities, and in cost constraints which ignore the long-term costs of unaverted infection.

Room for improvement
There was also evidence that exchanges had not sufficiently engaged with their customers to safeguard health, improve functioning, and reduce their risks of contracting or transmitting infection. For example, in 1995 visitors to seven of Glasgow’s NSPs were invited to undergo a medical examination (Gruer 1997) All the needle exchanges were based in clinics or health centres and were staffed by nurses and drug workers. All but a few of the NSP users said they had a current medical problem related to injecting and these were broadly confirmed by the examination. Yet over the previous six months three-quarters did not recall having been given health care at an exchange. Almost as many had not been referred to other services and of those who had, a third did not go.

Similarly in London researchers compared the performance of pharmacy NSP against specialist NSP based in drug agencies or operating as a standalone service. Despite greater resources, on some measures, sharing of injecting equipment was more prevalent among attenders at the specialist services. In both groups medical problems were common and often severe. As expected, the response from the specialist services was greater than that from pharmacies but it was still far from adequate. On a typical visit over a quarter and perhaps as many as 40% of callers left the service without having had a conversation with the staff. Despite their health problems, over the past year most could not recall being referred elsewhere for help, about 60% did not remember being advised to see their GP, over three-quarters had not seen a doctor or nurse at the agency, 4 in 10 had not discussed injecting with staff, and nearly half had not had their injecting sites inspected.


Are any harms caused by needle exchange?
The major concerns about NSPs are that they might encourage drug users to inject. In practice this could happen in several ways:

• the frequency of injecting might increase amongst long-term injectors as a result of an increased supply of equipment;

• injecting ‘careers’ may be extended because a legal and free supply of fresh equipment reduces the risks and the ‘hassle’ of sustaining such a career;

• for the same reasons, more people will be attracted into injecting.

None of these fears has been substantiated by the available research, a fact acknowledged by major international and national authorities (UN 2001, Canadian HIV/AIDS Legal Network 1997).

Amsterdam provides a clear answer to the fear that needle exchange will promote the spread of injecting. The city’s easy-access, ‘low threshold’ NSPs rapidly expanded from handing out 100,000 needles and syringes in 1985 to a million in 1990 Van Ameijden 2001). Between 1985 and 1988 the proportions of injectors (sampled mainly from methadone programmes) who exclusively sourced equipment from NSPs increased from 1 in 10 to two-thirds (Van den Hoek 1989).

Large amounts of equipment could be supplied at each visit. The supply from NSPs alone (pharmacies can also sell equipment to injectors) would have been enough to eliminate the need to borrow used equipment (Van Ameijden 1999). Yet between 1986 and 1998 a continuing study of drug users in the city recorded a drop in the proportion injecting from 66% to 36% due partly to a steep decline in the number of drug users starting to inject and an increase in the number of injectors abandoning the practice. In the early ’90s the city hosted perhaps 2500 injectors (Van Ameijden 1999) by 1997 just 1250.

Another study done in Anchorage in Alaska where US researchers conducted the first randomised trial of the impact of introducing NSP services (Fisher 2003), found no harms arising from the introduction of needle exchange.

600 injectors were randomly assigned to training in how to buy needles and syringes from pharmacies or to receive a card entitling them to use two new local NSPs. The exchange group could also use pharmacies but the pharmacy group could not use the NSPs. Interviews six and the 12 months later showed that both groups had made roughly equal reductions in past-month injection frequency and in the proportions of urine tests showing recent cocaine or heroin use. Though statistically insignificant, such differences as there were favoured the NSP group, who reduced injection frequency more quickly and made greater reductions in cocaine use.

Even in prisons, where there are concentrations of injectors who cannot otherwise easily obtain equipment, there is limited evidence that prisons which have introduced needle provision have reduced infection risk is not accompanied by any increase (and sometimes a decrease) in the extent of drug use (Dolan 2003).

City case studies of apparently ineffective needle exchange programmes
It is important for advocates of needle exchange to be aware of the circumstances that lie behind the case studies that are cited by opponents of needle exchange as 'proof that it doesn't work'.

Against this background of substantiated overall effectiveness, a series of city-based case studies published in the excellent British journal Drug and Alcohol Findings has explored the conditions which make NSP less effective, or at least seem so (Ashton 2003).

It explained that often NSP seems (wrongly) to be ineffective or worse due to the ‘magnet effect’. If a needle exchange succeeds in attracting people at high risk of contracting and spreading disease, this desirable feature can make it look as if it is not creating the intended changes in their behaviour. Attending the NSP may have substantially reduced their risk behaviour and chances of infection, but still these may remain higher than among injectors who do not attend. For the same reason, where a study finds that those attending NSP is associated with longer injecting careers, this is likely to be because 'committed injectors' choose to use NSPs rather than because the provision of needle exchange in itself prolongs injecting careers.

Taking this into account, still there remained examples where relatively widespread exchange provision had not been shown to adequately curb the spread of HIV and hepatitis C. Most notable was Vancouver - a case study often cited by opponents of needle exchange.

Alarm bells had rung when the city’s low HIV rate among injectors more than tripled over 18 months to reach 7% in 1995. It was a shock - because the city hosted the largest-volume NSP on the North American continent. A long-term study instigated the following year found that 23 of the 24 injectors who became HIV positive during the first six months of the study had been using NSP as their main source of injecting equipment.

These devastating findings were seized on by NSP opponents, and are still sometimes repeated today. However, a later report confirmed that NSP looked like a risk factor simply because infection-prone injectors regularly sourced their equipment from the exchange (Shecther 1999) But neither report found that NSP exerted a protective effect.

It was worse with respect to hepatitis C. Disturbingly, over half the injectors who had attended an NSP at least once a week had become newly infected with the virus but only a quarter of the less frequent customers. Even after taking other factors into account, frequent attenders remained two to three times more likely to become infected.

Behind these failures was an unusual conjunction of circumstances. Despite high volumes, the main exchange operated a tightly restricted service, partly because local opposition had forced it to adopt a defensive posture. Few syringes were handed out at one time, and there were restricted hours and a strict one-for-one policy (i.e. to get a syringe, you had to return one).

The area it worked in was and remains a drug-injecting ghetto, severely deprived, socially unstable with very poor housing consisting mainly of tiny hotel rooms whose young single, poor residents typically had histories of crime, abuse, and psychological problems. Into this vulnerable situation came an epidemic of cocaine injecting. The concentration of need and the frequency, irregularity, and compulsive nature of cocaine injecting overwhelmed local NSPs that had few support (especially addiction treatment) services to draw on.

At the other extreme was the example of Tacoma whose NSP was the first in the USA to gain public funding and legal approval. Tacoma shows that the right kind of exchange with sufficient support can be shown to be effective against not just HIV but also hepatitis C. From a one-man activist operation the NSP became an HIV prevention centre offering a comprehensive service from well-staffed premises. At the main sites there was no limit on supplies at any one time and exchange on behalf of others was encouraged.

There was, however, a strict one-for-one exchange policy. Staff spent considerable time educating and counselling callers and delivering on-site health and welfare services. Though risk was far from eliminated, studies strongly suggest that the NSP reversed an epidemic of hepatitis B among injectors and helped hold HIV down by roughly halving risky sharing. The chance to test whether these behaviour changes also curbed hepatitis C arose because the surrounding county was one of four designated nationally to monitor new cases. This data showed that after adjusting for other influences, an injector was seven times more likely to become infected with hepatitis C if they had not used the NSP, for hepatitis B, nearly six times (Hagan 1995).

Other studies reviewed by the journal indicated that ‘trickle feed’ NSP without sufficient volume and coverage cannot be expected to succeed, and that NSPs would need to become more proactive in their interventions and to forge partnerships with injecting networks if they were to combat hepatitis C and improve their anti-HIV record. Rather than showing that NSP is ineffective, the case studies are best taken as a reminder that NSP alone is not necessarily enough and that it cannot cope with extreme situations if its hands are tied and resources unduly limited.

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