Estimates of HIV infection among injecting drug users in Glasgow, 1985-1990

Empirical Bayes approach to estimating the number of HIV-infected individuals in hidden and elusive populations

In this paper we estimate the numbers of intravenous drug users (IVDUs) and commercial sex workers (CSWs) in Thailand infected with human immunodeficiency virus (HIV) who have not developed acquired immunodeficiency syndrome (AIDS) directly from the semi-annual HIV serosurveillance data of Thailand from June 1993 to June 1995. We propose a 'generalized removal model for open populations' for estimating HIV-infected population size within a hidden, elusive, and perhaps high-risk population group, for all sampling time when capture probabilities vary with time. We apply empirical Bayes methodology to the generalized removal model for open populations by using the Gibbs sampler, a Markov chain Monte Carlo method. No assumption on the size of the hidden population in question is needed to implement this procedure. The statistical method proposed here requires very little computing and only a minimum of two sets of serosurvey data to obtain an estimate, thereby providing a simple and viable option in epidemiological studies when either powerful computing facilities or abundant sampling data are lacking.

Epidemiology of HIV in Intravenous Drug Users and Public Health Policy in Germany

The paper assesses AIDS and drug policy development in Germany between 1982 and 1996 and relates it to the development of epidemiological research in HIV among injecting drug users (IDUs). In a historical review, this paper outlines how results of epidemiological HIV surveillance studies among IDUs and public health responses were mutually dependent. The authors argue that a specific development in HIV policy encouraged a confounding of basic methodological concepts (validity and precision) in epidemiological research, which in turn led to misinterpretation of available data on seroprevalence trends in Germany. In order to overcome methodological shortcomings under given legal and practical restrictions, pragmatic approaches to increase validity of seroprevalence and risk factor estimations are discussed.

Prevalence of markers for hepatitis B virus and HIV-1 among drug injectors in London: injecting careers, positivity and risk behaviour

Concerns about the risks of HIV infection among drug injectors have eclipsed concerns about the prevalence and transmission of hepatitis, and in particular hepatitis B virus infection. Findings are reported from surveys undertaken with two separate community-recruited samples of drug injectors in London collected in 1992 (n = 505) and in 1993 (n = 507). Anonymized confirmed testing of saliva shows 51.5% of drug injectors in 1992 and 47.9% in 1993 to be antibody positive to the core antigen of hepatitis B virus (anti-HBc). Approximately half of the drug injectors confirmed as anti-HBc positive were unaware that they had been infected with hepatitis. Anti-HIV-1 prevalence was considerably lower at 7.0% in 1992 and 6.9% in 1993. Multivariate analyses showed anti-HBc positivity to be most likely among older injectors with longer injecting careers who had a history of having shared used needles and syringes. HIV-1 positivity was also associated with a history of having shared injecting equipment as well as with recent sharing (i.e. in the last 6 months). Unlike anti-HBc positivity, there were no associations between HIV-1 positivity and age or length of injecting career. Younger injectors with shorter injecting careers were more likely to report recent sharing of used injecting equipment than older injectors with longer injecting careers. We note the potential for continued transmission of HBV and HIV-1, particularly among younger injectors. We recommend an integrated strategy to maximize the health of drug injectors, of which HIV and HBV prevention is a part. There is a need to widen the availability of HBV vaccinations for HBV negative drug injectors and their sexual partners and for clear guidelines to drug injectors about the relative efficacy of bleach to disinfect injecting equipment of HBV and HIV.

Methadone maintenance in general practice: patients, workload, and outcomes

OBJECTIVE

To assess recruitment to and work-load associated with methadone maintenance clinics in general practice; to investigate the characteristics of patients and outcomes associated with treatment.

DESIGN

Study of case notes.

SETTING

Methadone maintenance clinics run jointly by general practitioners and drug counsellors in two practices in Glasgow.

PARTICIPANTS

46 injecting drug users receiving methadone maintenance during an 18 month period, 31 of whom were recruited to clinic based methadone maintenance treatment and 15 of whom were already receiving methadone maintenance treatment from the general practitioners. Mean (SD) age of patients entering treatment was 29.6 (5.5) years; 29 were male. They had been injecting opiates for a mean 9.9 (5.1) years, and most had a concurrent history of benzodiazepine misuse. Average reported daily intake of heroin was approximately 0.75 g. Participants in treatment had high levels of preexisting morbidity, and most stated that they committed crime daily.

RESULTS

2232 patient weeks of treatment were studied. Mean duration of treatment during the study period was 50.7 (21.1) weeks and retention in treatment at 26 weeks was 83%. No evidence of illicit opiate use was obtained at an average of 78% of patients' consultations where methadone had been prescribed in the previous week; for opiate injection the corresponding figure was 86%.

CONCLUSIONS

Providing methadone maintenance in general practice is feasible. Although costs are considerable, the reduction in drug use, especially of intravenous opiates, is encouraging. Attending clinics also allows this population, in which morbidity is considerable, to receive other health care.

Prevalence of HIV and associated risk behaviour in attendees at a Dublin needle exchange

The aim of this study was to measure the prevalence of HIV infection and assess the level of equipment-sharing and unsafe sexual activity among attendees at a Dublin needle exchange. Using an anonymous unlinked approach, attendees were asked to complete a brief questionnaire and provide a sample of saliva for HIV testing. Of the 144 attendees eligible for inclusion during the study period, 106 agreed to participate and complete a questionnaire, a response rate of 74%. Of the 81 respondents who submitted a usable saliva sample, 14.8% were HIV positive. Half of the respondents claimed that they had not shared equipment during the preceding 28 days, but a third had shared with multiple partners. Half of the respondents claimed that they had multiple sexual partners during the preceding year, but only a quarter said that they always used condoms. The prevalence of HIV infection is similar to that found in routine linked testing of drug users in Ireland. The high level of unsafe injecting and sexual activity makes clear the need for more effective health promotion among drug users in Dublin.

Low and stable prevalence of HIV among drug injectors in Glasgow

The first HIV-positive diagnosis among injecting drug users (IDU) in Glasgow was made in 1985. By the end of 1987 prevalence among IDU receiving voluntary attributable tests was 4.8%. Since 1990, an annual cross-sectional survey of HIV prevalence and risk behaviours among 500 current Glasgow IDU has provided a more representative sample. Anonymously-tested saliva samples obtained from respondents revealed prevalence rates of 1.8%, 1.2% and 1.0% in 1990, 1991 and 1992 respectively. Since 1987 a wide range of measures aimed at reducing HIV-related risk behaviour among IDU has been introduced and maintained in Glasgow. Against this background, there is evidence that IDU in the city have reduced their risk behaviours. The findings reported here suggest that implementing harm-reduction measures when prevalence is low may inhibit the rapid dissemination of HIV.