Matthew Hickman

Incidence of hepatitis C virus and HIV among new injecting drug users in London: prospective cohort study

In England, the low prevalence of HIV among injecting drug users during the 1990s was attributed in part to the introduction of harm reduction interventions in the late 1980s. Also, the prevalence of hepatitis C virus in the late 1990s was thought to be relatively low compared with other countries, at around 40% overall and 15% among those who had been injecting drugs for less than six years.1 We carried out a prospective cohort study of new injecting drug users in London to estimate the incidence of hepatitis C virus and HIV. In 2001, we recruited from community settings mainly in London, but also in Brighton, 428 injecting drug users who were aged below 30 years or had been injecting for six years or fewer. All had injected in the previous four weeks and could provide addresses for follow up. They completed interviewer administered questionnaires and provided oral fluid specimens and optionally dried capillary blood spots for testing for antibodies to hepatitis C virus and HIV using published methods.2 3 They were followed up 12 months later. …

Methods to recruit hard-to-reach groups: comparing two chain referral sampling methods of recruiting injecting drug users across nine studies in Russia and Estonia.

Evidence suggests rapid diffusion of injecting drug use and associated outbreaks of HIV among injecting drug users (IDUs) in the Russian Federation and Eastern Europe. There remains a need for research among non-treatment and community-recruited samples of IDUs to better estimate the dynamics of HIV transmission and to improve treatment and health services access. We compare two sampling methodologies “respondent-driven sampling” (RDS) and chain referral sampling using “indigenous field workers” (IFS) to investigate the relative effectiveness of RDS to reach more marginal and hard-to-reach groups and perhaps to include those with the riskiest behaviour around HIV transmission. We evaluate the relative efficiency of RDS to recruit a lower cost sample in comparison to IFS. We also provide a theoretical comparison of the two approaches. We draw upon nine community-recruited surveys of IDUs undertaken in the Russian Federation and Estonia between 2001 and 2005 that used either IFS or RDS. Sampling effects on the demographic composition and injecting risk behaviours of the samples generated are compared using multivariate analysis. Our findings suggest that RDS does not appear to recruit more marginalised sections of the IDU community nor those engaging in riskier injecting behaviours in comparison with IFS. RDS appears to have practical advantages over IFS in the implementation of fieldwork in terms of greater recruitment efficiency and safety of field workers, but at a greater cost. Further research is needed to assess how the practicalities of implementing RDS in the field compromises the requirements mandated by the theoretical guidelines of RDS for adjusting the sample estimates to obtain estimates of the wider IDU population.

Drug-related mortality and fatal overdose risk: Pilot cohort study of heroin users recruited from specialist drug treatment sites in London

Fatal overdose and drug-related mortality are key harms associated with heroin use, especially injecting drug use (IDU), and are a significant contribution to premature mortality among young adults. Routine mortality statistics tend to underreport the number of overdose deaths and do not reflect the wider causes of death associated with heroin use. Cohort studies could provide evidence for interpreting trends in routine mortality statistics and monitoring the effectiveness of strategies that aim to reduce drug-related deaths. We aimed to conduct a retrospective mortality cohort study of heroin users recruited from an anonymous reporting system from specialist drug clinics. Our focus was to test whether (1) specialist agencies would agree to participate with a mortality cohort study, (2) a sample could be recruited to achieve credible estimates of the mortality rate, and (3) ethical considerations could be met. In total, 881 heroin users were recruited from 15 specialist drug agencies. The overall mortality rate of the cohort of heroin users was 1.6 (95% confidence interval [CI], 1.1 to 2.2.) per 100 person-years. Mortality was higher among males, heroin users older than 30 years, and injectors, but not significantly higher after adjustment in a Cox proportional hazard model. Among the 33 deaths, 17 (52%) were certified from a heroin/methadone or opiate overdose, 4 (12%) from drug misuse, 4 (12%) unascertained, and 8 (24%) unrelated to acute toxic effects of drug use. Overall, the overdose mortality rate was estimated to be at least 1.0 per 100 person-years. The standardized mortality ratio (SMR) was 17 times higher for female and male heroin users in the cohort compared to mortality in the non-heroin-using London population aged 15–59 years. The pilot study showed that these studies are feasible and ethical, and that specialist drug agencies could have a vital role to play in the monitoring of drug-related mortality.

Modelling the force of infection for hepatitis B and hepatitis C in injecting drug users in England and Wales

BackgroundInjecting drug use is a key risk factor, for several infections of public health importance, especially hepatitis B (HBV) and hepatitis C (HCV). In England and Wales, where less than 1% of the population are likely to be injecting drug users (IDUs), approximately 38% of laboratory reports of HBV, and 95% of HCV reports are attributed to injecting drug use.MethodsVoluntary unlinked anonymous surveys have been performed on IDUs in contact with specialist agencies throughout England and Wales. Since 1990 more than 20,000 saliva samples from current IDUs have been tested for markers of infection for HBV, HCV testing has been included since 1998. The analysis here considers those IDUs tested for HBV and HCV (n = 5,682) from 1998–2003. This study derives maximum likelihood estimates of the force of infection (the rate at which susceptible IDUs acquire infection) for HBV and HCV in the IDU population and their trends over time and injecting career length. The presence of individual heterogeneity of risk behaviour and background HBV prevalence due to routes of transmission other than injecting are also considered.ResultsFor both HBV and HCV, IDUs are at greatest risk from infection in their first year of injecting (Forces of infection in new initiates 1999–2003: HBV = 0.1076 95% C.I: 0.0840–0.1327 HCV = 0.1608 95% C.I: 0.1314–0.1942) compared to experienced IDUs (Force of infection in experienced IDUs 1999–2003: HBV = 0.0353 95% C.I: 0.0198–0.0596, HCV = 0.0526 95% C.I: 0.0310–0.0863) although independently of this there is evidence of heterogeneity of risk behaviour with a small number of IDUs at increased risk of infection. No trends in the FOI over time were detected. There was only limited evidence of background HBV infection due to factors other than injecting.ConclusionThe models highlight the need to increase interventions that target new initiates to injecting to reduce the transmission of blood-borne viruses. Although from the evidence here, identification of those individuals that engage in heightened at-risk behaviour may also help in planning effective interventions. The data and methods described here may provide a baseline for monitoring the success of public health interventions.

Prevalence of, and risk factors for, hepatitis C virus infection among recent initiates to injecting in London and Glasgow: cross sectional analysis.

Summary.  Our aim was to compare the prevalence of antibody to hepatitis C virus (anti‐HCV) among recently initiated injecting drug users (IDUs) in London and Glasgow, and to identify risk factors which could explain differences in prevalence between the cities. Complementary studies of community recruited IDUs who had initiated injection drug use since 1996 were conducted during 2001–2002. Data on HCV risk behaviours were gathered using structured questionnaires with identical core questions and respondents were asked to provide an oral fluid specimen which was tested anonymously for anti‐HCV but was linked to the questionnaire. Sensitivities of the anti‐HCV assays for oral fluid were 92–96%. Prevalence of anti‐HCV was 35% (122/354) in London and 57% (207/366) in Glasgow (P < 0.001). Multifactorially, factors significantly associated with raised odds of anti‐HCV positivity were increasing length of injecting career, daily injection, polydrug use, having had a needlestick injury, and having served a prison sentence. In addition lower odds of anti‐HCV positivity were associated with non‐injection use of crack cocaine and recruitment from drug agencies. After adjustment for these factors, the increased odds of anti‐HCV associated with being a Glasgow IDU were diminished but remained significant. HCV continues to be transmitted among the IDU population of both cities at high rates despite the availability of syringe exchange and methadone maintenance. Effectiveness of harm reduction interventions may be compromised by inadequate coverage and failure to reduce sufficiently the frequency of sharing different types of injecting equipment, as well as the high background prevalence of HCV, and its high infectivity. Comprehensive action is urgently required to reduce the incidence of HCV among injectors.

Outcomes of universal antenatal screening for haemoglobinopathies

Objective To evaluate universal antenatal screening for haemoglobinopathies. Setting District general hospital serving a London borough with 45% ethnic minorities. Methods Retrospective cohort study of 1444 women referred in 1688 pregnancies and 95 tertiary referrals during 101 pregnancies. Results Unselected women at risk for sickle cell disease booked 2.7 weeks (95% confidence interval (CI) 0.14 to 5.1) later in gestation than those at risk for β thalassaemia were less likely to attend counselling (83% v93%, relative risk (RR) 0.89; 95% CI 0.85 to 0.94), their partners were less likely to be tested (77% v 95%, RR 0.81; 0.77 to 0.83), and they were less likely to accept prenatal diagnosis (22% v 90%, RR 0.37; 0.24 to 0.57). Over 99% of tertiary referrals attended counselling and had their partners tested. There were no significant differences in acceptance of prenatal diagnosis between those at risk of sickle cell disease and β thalassaemia (55% v 67%). Unselected women at risk of sickle cell disease were significantly less likely to have their partner tested or to accept prenatal diagnosis than tertiary referrals, but not those at risk of β thalassaemia. 80% of β thalassaemia and 16% of SS births were prevented. Conclusions Uptake of prenatal diagnosis among unselected women at risk of β thalassaemia is similar to that reported by tertiary centres. It is considerably lower for sickle cell disease but could increase considerably if screening occurred earlier in gestation. Acceptance of counselling is universally high, suggesting that informed choices are made, and indicating a need to measure these outcomes for cost effectiveness studies.

Hepatitis C virus infection, HIV co-infection, and associated risk among injecting drug users in Togliatti, Russia:

The objective of this study was to estimate the prevalence of hepatitis C virus (HCV) infection and co-infection with HIV among injecting drug users (IDUs) in Togliatti City, Russia. Unlinked anonymous cross-sectional survey of IDUs recruited from community settings, with oral fluid sample collection for HCV and HIV antibody (anti-HCV, anti-HIV) testing, was carried out. The anti-HCV prevalence was 87% (357/411), anti-HIV prevalence 56% (234/418), and 93% (214/230) of HIV-positive IDUs were co-infected with HCV. Only 23% (94/411) of those HCV positive self-reported as such. In an adjusted model, increased odds of HCV positivity were associated with needle and syringe, as well as injecting paraphernalia sharing in the last four weeks. IDUs injecting more than once with the same needle also had raised odds. There were no marked associations between HCV positivity and the duration of injecting or age group. Almost all IDUs were HCV positive, and almost all HIV-positive IDUs were HCV co-infected. There is an urgent need to maximize syringe distribution coverage, develop health promotion targeting HCV prevention for IDUs, and improve access among IDUs to treatments for HIV and HCV infection.

Estimating the size and dynamics of an injecting drug user population and implications for health service coverage: comparison of indirect prevalence estimation methods

AIMS (i) To compare indirect estimation methods to obtain mean injecting drug use (IDU) prevalence for a confined geographic location; and (ii) to use these estimates to calculate IDU and injection coverage of a medically supervised injecting facility. DESIGN Multiple indirect prevalence estimation methods. SETTING Kings Cross, Sydney, Australia. PARTICIPANTS IDUs residing in Kings Cross area postcodes recorded in surveillance data of the Sydney Medically Supervised Injecting Centre (MSIC) between November 2001 and October 2002. MEASUREMENTS Two closed and one open capture-recapture (CRC) models (Poisson regression, truncated Poisson and Jolly-Seber, respectively) were fitted to the observed data. Multiplier estimates were derived from opioid overdose mortality data and a cross-sectional survey of needle and syringe programme attendees. MSIC client injection frequency and the number of needles and syringes distributed in the study area were used to estimate injection prevalence and injection coverage. FINDINGS From three convergent estimates, the mean estimated size of the IDU population aged 15-54 years was 1103 (range 877-1288), yielding a population prevalence of 3.6% (2.9-4.3%). Mean IDU coverage was 70.7% (range 59.1-86.7%) and the mean adjusted injection coverage was 8.8% (range 7.3-10.8%). Approximately 11.3% of the total IDU population were estimated to be new entrants to the population per month. CONCLUSIONS Credible local area IDU prevalence estimates using MSIC surveillance data were obtained. MSIC appears to achieve high coverage of the local IDU population, although only an estimated one in 10 injections occurs at MSIC. Future prevalence estimation efforts should incorporate open models to capture the dynamic nature of IDU populations.

Arrest Referral in London Police Stations: characteristics of the first year. A key point of intervention for drug users?

The paper examines the demographic, drug use and offending profile of arrestees in contact with arrest referral (AR) schemes in London, compares these contacts with the arrestee population as a whole, and with drug users presenting to treatment services in the community, and assesses the proportion and characteristics of AR contacts that go on to attend drug-treatment services. Routine monitoring data from AR schemes (April 2000 to March 2001) were analysed and compared with data ( for equivalent time period) on arrestees from the Crime Reporting Information System (CRIS) and data from the National Drug Treatment Monitoring System (NDTMS). AR schemes see about 10% of arrestees in London. Approximately half of those assessed by an AR worker report using heroin (55%) and crack cocaine (49%) with a similar proportion (51%) having no previous contact with drug-treatment services. The large majority (80%) report previous convictions. Of those referred by AR workers (50% of assessments) between 25 and 37% attend a first appointment at a drug-treatment service. Drug users seen by AR workers are younger, more likely to come from ethnic minorities and more likely to be using crack cocaine than those presenting to treatment services in the community. AR is a key point of contact with problem drug users, including those considered under-represented at drug-treatment services. However, to fully assess the effectiveness of AR, further information is required about retention in treatment and its effect on drug use and offending behaviour.

Twenty years of selective hepatitis B vaccination: is hepatitis B declining among injecting drug users in England and Wales?

Summary.  Injection drug use is a common route of infection for the hepatitis B virus (HBV) in the UK. The aim of this study was to establish the prevalence and force of infection for HBV among injecting drug users (IDUs) recruited from multiple community and drug agency settings in England and Wales between 1990 and 2004. Cross‐sectional studies of IDUs in and out of contact with drug agencies were conducted throughout the 15‐year period. Oral fluid samples were tested for antibodies to the hepatitis B core antigen (anti‐HBc). Logistic regression was used to investigate associations between risk factors and anti‐HBc positivity and force of infection models were explored. In total, 2527 injectors were recruited from community settings, and 29 386 from drug agencies. Anti‐HBc prevalence was 31% (95% CI 30.7–31.8%). It declined in the early 1990s from around 50% in 1992 to 25% in 1999, after which it increased slightly. It was also higher in those who had injected for longer, older IDUs, those recruited in London and North West England, and those reporting having a previous voluntary confidential HIV test. The force of infection models suggested that the incidence of infection increased in 1999–2004 compared with 1993–1998, and was higher in new injectors compared with those injecting for ≥1 year. In conclusion, findings suggest ongoing HBV transmission in recent years despite an overall decline in prevalence in the early and mid‐1990s, and highlight the importance of targeting vaccination programmes at new IDUs who have high incidence rates of infection.