Sustained increase in the sharing of needles and syringes among drug users in England and Wales

Monitoring injecting drug users risk behaviours is important because changes in these can rapidly increase blood-borne virus transmission rates. In England and Wales needle and syringe sharing in the previous month has been monitored through annual cross-sectional surveys since 1991. After declining in the early 1990s, the proportion sharing increased significantly between 1997 and 2000. This, and an apparent increase in hepatitis B transmission, indicates that injectors are at an increasing risk of infection with blood-borne viruses. Needle and syringe (direct) sharing by injecting drug users (IDU) has been recognized since the early 1980s as a route for the transmission of HIV. In response many countries introduced harm-reduction interventions, such as methadone prescribing and needle and syringe exchange. Countries such as the UK, which promptly introduced a comprehensive intervention programme, have low or declining HIV prevalences among IDU [1,2]. The monitoring of IDU is important because changes in drug use and injecting risk behaviour can rapidly increase HIV transmission rates, as occurred in Canada [3,4]. In England and Wales, data on direct sharing has been collected from IDU in contact with a sample of drug services since 1991 [5], and on other (indirect) sharing practices, such as sharing spoons and filters, since 1996 [6]. Clients of collaborating services, who have ever injected drugs, are asked to participate. Those who consent provide an oral fluid sample, for anti-HIV, anti-hepatitis B core (HBc) and anti-hepatitis C virus (HCV) testing, [7] and complete a brief questionnaire [5]. Statistical analyses were undertaken in SPSS. Between 1991 and 2000 there were 21 161 participations by current injectors (IDU who had injected in the preceding month) out of a total of 30 806 participations. Of the participations by current injectors, 22% (4646/20 786) were women, 34% (6977/20 484) were aged under 25 years, and 20% (4181/21 161) were recruited in London. In 2000 the prevalences of anti-HIV, anti-HBc and anti-HCV among current injectors were 0.8% (20/2488), 20% (490/2487) and 31% (775/2488), respectively. Direct sharing in the previous month changed over time; after an initial decline in the early 1990s there was a significant increase between 1997 and 2000, from 21% (71/337) to 41% (123/298) in London, and from 17% (237/1431) to 29% (549/1886) elsewhere (Fig. 1). These changes remained after adjustment for covariates (age, sex and recruitment location) using multivariable logistic regression (Fig. 1).Fig. 1.: Needle and syringe sharing by current injectors and the number of reports of acute hepatitis B infection associated with injecting drug use: England and Wales, 1991–2000. (a) Needle and syringe sharing (passing on, or receiving, used needles or syringes) in the 4 weeks prior to participating in the Unlinked Anonymous Survey of Injecting Drug Users, London (n = 3615). ▒ Proportion; ―◆― adjusted odds ratio (with 95% confidence intervals) adjusted for recruitment location, age at participation and gender. (b) Needle and syringe sharing (passing on, or receiving, used needles or syringes) in the 4 weeks prior to participating in the Unlinked Anonymous Survey of Injecting Drug Users, England and Wales outside London (n = 15 171). ▒ Proportion; ―◆― adjusted odds ratio (with 95% confidence intervals) adjusted for recruitment location, age at participation and gender. (c) Laboratory reports of acute hepatitis B associated with injecting drug use, England and Wales. Source: http://www.phls.co.uk/facts/Hepatitis/Hep%20B/hepb-t07.htm, accessed 19 November 2001, 2000 data provisional.The increase in sharing between 1997 and 2000 was seen in both men, from 16% (218/1367) to 28% (478/1683), and women, from 23% (90/393) to 39% (191/485), and across all age groups, from 25% (121/485) to 31% (187/606) in under 25 year olds, from 17% (148/885) to 31% (326/1067) in 25–34 year olds, and from 9% (30/349) to 31% (149/479) in those over 34 years of age. The proportion of current IDU reporting indirect sharing was found not to have changed since measurement started in 1996, and in 2000 was 62% (193/310) in London and 53% (1055/1976) elsewhere. To explore the impact of the increase in direct sharing on blood-borne virus transmission the prevalences of anti-HBc and anti-HCV among recent initiates (those current injectors who had started injecting in the past 2 years) were examined. An increase in the prevalence in this group over time would be suggestive of an increase in incidence. The anti-HBc prevalence among this group increased significantly between 1997 and 2000, from 2.9% (13/449) to 6.7% (41/614) χ2df = 1(forlinearassociation) = 7.100, P = 0.008, whereas that for anti-HCV did not change between 1998 (8.1%, 48/595) when testing started and 2000 (8.5%, 52/614). The anti-HIV prevalence was very low among this group and so could not be examined (overall prevalence during the period 1997–2000 was 0.18%, 4/2278). This increase in direct sharing among IDU and the increase in the prevalence of hepatitis B among recent initiates suggests that those who inject drugs may be at increasing risk of infection with blood-borne viruses. The significance of these increases depends upon the representativeness of our survey. The marginalization and illegality of drug injecting, however, impede the construction of a sampling frame. As this survey was recruited from a wide range of locations and service types using a consistent methodology over time it is likely to be representative of IDU in contact with services. The existence of the increase in the risk of infection is supported by a rise in the annual number of acute hepatitis B reports associated with injecting drug use (Fig. 1) [6]. This increase in sharing may lead to increased HIV transmission; however, the prevalence of HIV among current IDU in England and Wales is very low and appears not to have changed in recent years [6,8]. This low prevalence and the selective nature of sharing, with injectors tending to share only with their sexual partners or close friends [9], suggest that although opportunities for HIV transmission through injecting are likely to have increased, actual transmission probably remains rare. Indirect sharing is thought to play a much greater role in the transmission of hepatitis C than HIV and hepatitis B [10]. The stable prevalence of hepatitis C may therefore be related to the fact that the proportion of injectors reporting indirect sharing has not changed over time. This study did not investigate reasons as to why direct sharing has increased; this increase has, however, occurred at a time of increased sexual risk behaviours [11,12], which have been attributed to changed perceptions of the severity of HIV infection following advances in treatment. Other possible explanations include IDU no longer perceiving themselves to be at high risk of infection, and increased constraints on the availability of sufficient clean needles and syringes. IDU risk-reduction strategies are, however, complex and fluid, and can include the cleaning of works before re-use and being selective about sharing/injecting partners [13]. Changes in these behaviours are not currently monitored, as methods for measuring these need further development [13]. The importance of the coverage of needle and syringe provision has been shown by the increase in HIV prevalence among IDU in Vancouver, a city with a large established needle exchange programme [3]. This rise has been associated, at least partly, with an increase in injection frequency (as a result of a growth in cocaine use) that was not matched by an increased supply of needles and syringes [14]. In the United Kingdom the coverage of needle and syringe distribution is not known, although it has been estimated that 25 million syringes were distributed in 1997 after a decade of service expansion [15]. Service development has continued with the implementation of a national strategy for reducing problem drug use [16], although with a focus on improving access to treatment. The findings presented here suggest that the ongoing provision of needle exchange, and other harm-reduction measures, may not be sufficient to maintain reductions in risk behaviour. If low HIV prevalences among IDU are to be sustained then interventions to maintain the reduction in direct sharing, as well as measures to ensure adequate service coverage, may need development. Contributions V.D. Hope, L. Jordan and T. Paine were responsible for the day-to-day co-ordination of the survey. O.N. Gill manages the survey and, with J.V. Parry, was involved with its design. Laboratory work was undertaken by S. Barnett. Analysis was undertaken by P. Rogers assisted by V.D. Hope. All authors contributed to the writing of the paper, with V.D. Hope leading. Acknowledgements The authors would like to thank all the drug services who collaborated with the survey and all the injectors who took part. They would also like to thank Shona Livingstone for her assistance with the preliminary statistical analyses. This survey of IDU is part of the Unlinked Anonymous Prevalence Monitoring Programme, which is funded by the Department of Health.

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