A comparison of different methods for estimating the prevalence of problematic drug misuse in Great Britain

AIMS

The European Monitoring Centre for Drugs and Drug Addiction (EMCDDA) has produced methodological guidelines for national drug prevalence estimation. This paper pilots the methods to estimate prevalence for Great Britain and provides a commentary on the methods and resulting estimates.

DESIGN

Three types of methodology were used to estimate prevalence: (a) the multiple indicator (MI) method, (b) multipliers applied to (i) drug-treatment records (ii) HIV estimates and (iii) mortality statistics and (c) the British/Scottish Crime Surveys.

SETTING

England, Scotland and Wales.

PARTICIPANTS

Aggregated data on people recorded on databases and respondents in household surveys.

MEASUREMENTS

Prevalence estimates of different forms of problematic drug use.

FINDINGS

The estimates are 161,133 (range: 120,850-241,700) for people at risk of mortality due to drug overdose; 161,000-169,000 for people who have ever injected drugs; 202,000 (range: 162,000-244,000) problem opiate users and 268,000 problem drug users (all types).

CONCLUSIONS

The multiple indicator method offers a comprehensive approach to estimating the prevalence of problematic drug use in the United Kingdom. Simple multiplier methods and household surveys also provide a range of estimates corresponding to different types of drug use in the United Kingdom. The current study suggests that previous national estimates of 100,000-200,000 were conservative. The new estimate of 161,000-266,000 should enable a more focused response. For further development of this method, reliable and timely estimates of anchor points are required for specific geographical areas such as cities or Drug Action Teams (DAT), as well as routine aggregation of drug indicators for these areas.

Siblings, multiple births, and the incidence of allergic disease: a birth cohort study using the West Midlands general practice research database

BACKGROUND

The presence of older siblings reduces the risk of developing hay fever, eczema and atopy, but findings for asthma have been inconsistent. Whether twins have a reduced risk of allergic disease is also unclear. We have investigated these questions in a birth cohort analysis of the West Midlands General Practice Research Database (GPRD).

METHODS

Our birth cohort included 29,238 children. The incidence of allergic disease was examined according to the number of siblings, multiple births, and parental allergic disease and smoking habit using Cox regression.

RESULTS

There was a dose related decrease in the incidence of eczema and hay fever with increasing number of older siblings (hazard ratio for children with three or more older siblings compared with none 0.70 (95% CI 0.64 to 0.76) for eczema and 0.67 (95% CI 0.52 to 0.86) for hay fever). In contrast, the presence of older siblings increased the incidence of asthma (HR 1.17, 95% CI 1.06 to 1.29), although this effect was strongly dependent on age of diagnosis. For children diagnosed over the age of 2 years the presence of older siblings was protective (HR 0.66, 95% CI 0.52 to 0.82), while below this age the reverse was true (HR 1.38, 95% CI 1.24 to 1.54). Members of a multiple birth had a reduced incidence of all three allergic diseases. Birth order and multiple birth effects were independent of sex, maternal age, consulting behaviour, and parental allergy and smoking habit.

CONCLUSIONS

The presence of older siblings and being a member of a multiple birth appears to protect against the development of eczema, hay fever, and asthma diagnosed after the age of 2. In contrast, the presence of older siblings increases the incidence of early asthma.

Trends in antibiotic prescribing and associated indications in primary care from 1993 to 1997

BACKGROUND

Recent concerns that evidence on the appropriate use of antibiotics is not having an impact on prescribing trends are based on UK prescribing data relating to 1980-1991. The aim of this paper is to determine trends in antibiotic prescribing from 1993 to 1997 and link antibiotic prescriptions to diagnostic categories.

METHODS

A retrospective analysis of antibiotic prescriptions linked to diagnostic codes was carried out using the West Midlands General Practice Research Database.

RESULTS

The prescribing rate for antibiotics fell from 963 prescriptions/1,000 patients in 1993 to 807 prescriptions/1,000 patients in 1997 (p < 0.001). The proportion of antibiotic prescribing for respiratory conditions fell from 65 per cent in 1993 to 59 per cent in 1997 (p < 0.001). The main decreases in antibiotic prescribing are accounted for by non-specific lower respiratory tract infections (-22 prescriptions/1,000 patients), non-specific upper respiratory tract infections (-21/1,000 patients) and throat infections (-20/1,000 patients). There was increased prescribing for non-respiratory miscellaneous conditions (+6 prescriptions/1,000 patients).

CONCLUSIONS

Overall antibiotic prescribing declined by 16 per cent between 1993 and 1997, primarily for respiratory conditions. These results of the current study are in marked contrast to an earlier review, which found an increase of 46 per cent between 1980 and 1991 in England. The level of antibiotic prescribing for conditions which may not be bacterial in origin is still high and there is scope for further reductions in antibiotic prescribing. This study highlights the need for regular epidemiological data to inform the debate on antibiotic prescribing.

Computerized projection of future heroin epidemics: a necessity for the 21st century?

Although U.K. has seen significant advances in knowledge since the onset of its last major heroin epidemic in the early 1980s, it is still the case that most assessments of the extent of drug misuse are based on old data. Recognition of this problem is evidenced by the many attempts elsewhere to reduce the lag between data collection and data use in such programs as DAWN, ADAM, and PULSE CHECK. Such programs are an improvement, but they are nevertheless still estimates of unknown reliability, and still about the past rather than about the future. Building on the pioneering work of Hunt and Chambers in the 1970s, the authors present the output of a computerized model that attempts to forecast the heroin epidemics of the future.

Are triptans with enhanced lipophilicity used for the acute treatment of migraine associated with an increased consulting rate for depressive illness?

1997, sumatriptan-treated migraineurs had significantly higher depression PCRs (22.3%) compared with non-triptan users (19.3%), a difference of 6.4% (95% confidence interval (CI) 4.6-8.4%, P < 0.001). In the year (April 1997 to March 1998) following the launch of the TELs, depression PCRs were significantly higher among patients using these compounds compared with sumatriptan-treated patients (5.1%, CI 1.8-12.0%, P < 0.05). However, after taking account of prior depression (odds ratio (OR) 6.45, 95% CI 3.63-11.43), TELs were not significantly associated with depression (OR 0.27, 95% CI 0.03-2.13). Furthermore, rates of newly diagnosed depression after treatment were similar in the two triptan groups (sumatriptan 4.2%; TELs 3.9%). Although, the TELs are being prescribed to patients with higher pre-existing rates of depression, they are not associated with subsequently increased consulting for depressive illness compared with patients taking sumatriptan. This study highlights the potential to use GPRD to test targeted hypotheses exploring pharmacovigilance issues for patients using new medicines.

A comparison of trends in problematic drug misuse from two reporting systems

BACKGROUND

Regional Drug Misuse Databases (RDMDs) are considered the main source of intelligence on problem drug takers in England. Originally intended to provide trend data on visible drug use, a recent strategic review concluded that their purpose should be to monitor treatment targets for the Government's latest 10 year strategy to tackle drug misuse. The aim of this analysis was to explore whether the General Practice Research Database (GPRD) could supplement RDMDs.

METHODS

A retrospective analysis was carried out using the GPRD and the RDMD in the West Midlands from 1993 to 1997.

RESULTS

Extrapolation of GPRD data indicates 6,574 drug misusing or dependent diagnosed patients in primary care in 1997 compared with 3,643 clients reported by all agencies including general practitioners (GPs) to the RDMD. From 1993 to 1997, the RDMD notification rate fluctuated whereas the GPRD rate has increased steadily since 1995. Half of all drug misusing or dependent patients recorded on the GPRD had psychiatric co-morbidity and 10 per cent had been referred to hospital for a drug overdose.

CONCLUSIONS

As the GPRD has been unaffected by the demise of statutory notification of drug dependence in 1997, interpretation of trends may be more reliable than on the RDMD. There is also considerable potential for analysis of prescribing patterns, co-morbidity and drug-related hospitalization. As the Department of Health's Strategic Review of RDMDs recommends GPs as 'core reporters' for providing data to the national system, there is a need for a strategy to ensure valid and comprehensive reporting from GPs.

Extent and contributing factors of drug expenditure of injectors in Glasgow. Multi-site city-wide cross-sectional study

BACKGROUND

Recent concern about drug use has focused attention on the illegal income generated by users.

AIMS

To investigate factors associated with drugs expenditure and to estimate the cost of illegal acquisitions used to pay for drugs.

METHOD

We collected self-report data from 954 current injectors, interviewed at multiple street, needle/syringe exchange and drug treatment sites throughout Glasgow.

RESULTS

Injectors' mean weekly drug spending was 324 Pounds. The mean annual illegal drugs spend was estimated to be 11,000 Pounds per injector. We provide a central estimate--194 million Pounds per annum--of the retail value of goods acquired illegally by injectors in Glasgow in order to pay for drugs. Higher drug spends were associated with having been imprisoned more often and with those reporting acquisitive crime, drug dealing and prostitution. Treatment with methadone, among individuals who injected in the previous two months, was associated with a 20% reduction in a typical spend on drugs.

CONCLUSIONS

Treatment effectiveness needs to be measured both in terms of health benefit and in terms of reduction in drugs expenditure and recidivism.

Ratio of inhaled corticosteroid to bronchodilator treatment and asthma hospitalisation

BACKGROUND

Previous research based on aggregated data has led to conflicting interpretations of the relationship between the corticosteroid:bronchodilator (C:B) ratio and outcome measures.

OBJECTIVES

To assess whether the C:B ratio is associated with hospital contact for asthma at individual patient level.

METHODS

The study was a retrospective multivariate analysis, using data from the U.K. General Practice Research Database from 1993 to 1996. The subjects were 3465 asthma-diagnosed patients receiving bronchodilator and corticosteroid medication. The main outcome measures were asthma-related hospital contacts.

RESULTS

There was an inverse association between the C:B ratio and hospital contact after controlling for age. The odds ratio for the C:B ratio was 0.87 (95 % CI 0.73-0.98) and 1.04 (95% CI 1.01-1.07) for five-year agebands among patients aged five years and over. There was no systematic relationship between the C:B ratio and hospital contacts for patients aged under five years.

CONCLUSION

The results of this study show that higher C:B ratios are associated with lower levels of hospital contacts at patient level, although there are exceptions possibly linked to disease severity. For patients under five years, the ratio may not be a good outcome measure, perhaps owing to the difficulty in diagnosing asthma or poor compliance.

Estimating the prevalence of problem drug use in inner London: a discussion of three capture-recapture studies

AIMS

To provide an evidence base of estimates of the prevalence of problem drug use in inner London.

DESIGN

Re-analysis of three capture-recapture studies using subjects aged 15-49 years, that aim to estimate the hidden population from analysing the overlaps between three data sources.

SETTING

Newham (1995) Camden and Islington (C&I) (1993/4) and Lambeth, Southwark and Lewisham (LSL) (1992).

PARTICIPANTS

Each study collected data from three sources of problem drug users including: the Regional Drug Misuse Database, specialist drug agencies, HIV tests, social services, police arrests and court records. In LSL opiate users were analysed separately. The studies identified 1832 individuals in LSL, 543 in Newham, and 1321 in C&I.

MEASUREMENTS

Poisson models were fitted to the data testing different interactions between the data sources representing potential dependencies. The simplest model was selected on the basis of its AIC score and log-likelihood ratio tests.

FINDINGS

The number of hidden problem drug users were estimated to be 12,500 (95% CI 9600-16,100) in LSL with 4400 (3200-6100) opiate users; 7000 (5000-10,000) in C&I and 3800 (2000-7200) in Newham. The prevalence of problem drug use in those aged 15-49 was estimated to be 3.1% (2.5-3.9%) in LSL with 1.3% (1.0-1.6%) opiate users; and 3.6% (2.7-4.9%) and 3.3% (1.9-5.7%) in C&I and Newham, respectively.

CONCLUSIONS

Despite the inherent problems with capture-recapture methods, our three studies establish an evidence base for estimates of problem drug use in London. It is important that a larger study is carried out in London.

Should the corticosteroid to bronchodilator ratio be promoted as a quality prescribing marker?

In recent years the ratio of inhaled corticosteroid:bronchodilator (C:B) prescribing has been promoted as a quality marker for asthma treatment and cross-sectional data indicate an association with hospital admissions. If prescribing advice has been followed then it can be hypothesised that the C:B ratio will have increased and hospitalisation decreased. The West Midlands General Practice Research Database was used to monitor changes in the C:B ratio and hospital referrals for asthma between 1993 and 1996. The C:B ratio increased from 0.5 to 0.6 (P<0.001) and hospital referrals decreased from 7% to 4% per annum (P<0.001). Overall, 38% of the variation in hospital referrals was explained by the C:B ratio. This is higher than previous studies, perhaps because the study was longitudinal and the ratio assessed accurately in terms of volume rather than prescription items. When measured in defined daily doses, the C:B ratio does appear to have validity as an indicator of good prescribing in primary care. The General Practice Research Database offers an opportunity for assessing the validity of prescribing indicators before they are considered for wider use by Primary Care Groups and Health Authorities.

Mortality and survival among a cohort of drug injectors in Glasgow, 1982-1994

There has been much speculation about the nature and extent of mortality among drug injectors in Glasgow. In order to determine injectors' mortality rate and compare this rate to the general population, identifier information from 459 drug injectors who received treatment for drug misuse in Glasgow between 1982 and 1994 was linked to the Scottish Mortality Register. The average duration of follow-up from cohort entry was 5.5 years and 10.2 years from commencement of drug injection. By the end of 1994, 53 cohort members had died. The average annual mortality rate of 1.8% was the same as that observed in a London cohort followed-up from 1969 to 1991. However, the excess mortality ratio (EMR) of 22.0 was almost double the London rate (11.9) because of the much lower average age of mortality (26.3 vs. 38.2 years). There was no significant time trend in EMR. Kaplan-Meier hazard analyzes show that younger patients and those who were HIV positive had significantly elevated mortality rates. The main cause of death was overdose, although it is unclear how many were accidental and how many intentional. Three of the six fatalities among HIV positive injectors were AIDS related. This study enables the first realistic assessment of the hypothesis that drug-related deaths in Glasgow are especially high. In relation to other populations of drug injectors, the annual mortality rate is comparable, although the average age of mortality is much lower in Glasgow. Consequently, in comparison to the general population, the mortality rate of drug injectors is higher in Glasgow compared to other cities.

Maintaining low HIV seroprevalence in populations of injecting drug users

OBJECTIVES

To describe prevention activities and risk behavior in cities where human immunodeficiency virus (HIV) was introduced into the local population of injecting drug users (IDUs), but where seroprevalence has nevertheless remained low (< 5%) during at least 5 years.

DESIGN AND SETTING

A literature search identified five such cities: Glasgow, Scotland; Lund, Sweden; Sydney, New South Wales, Australia; Tacoma, Wash; and Toronto, Ontario. Case histories were prepared for each city, including data on prevention activities and current levels of risk behavior among IDUs.

PARTICIPANTS

Injecting drug users recruited from both drug treatment and non-treatment settings in each city.

INTERVENTIONS

A variety of HIV prevention activities for IDUs had been implemented in each of the five cities.

RESULTS

There were three common prevention components present in all five cities: (1) implementation of prevention activities when HIV seroprevalence was still low, (2) provision of sterile injection equipment, and (3) community outreach to IDUs. Moderate levels of risk behavior continued with one third or more of the IDUs reporting recent unsafe injections.

CONCLUSIONS

In low-seroprevalence areas, it appears possible to severely limit transmission of HIV among populations of IDUs, despite continuing risk behavior among a substantial proportion of the population. Pending further studies, the common prevention components (beginning early, community outreach, and access to sterile injection equipment) should be implemented wherever populations of IDUs are at risk for rapid spread of HIV.

The preparedness to share injecting equipment: an analysis using vignettes

This paper reports on the use of vignettes to study drug injectors' preparedness to share injecting equipment. Separate vignettes referring to borrowing and passing on injecting equipment have been submitted to 505 injecting drug users in Glasgow. Injectors were asked to identify their own likely response in each of the situations described within the vignettes. It was shown that even among those injectors not reporting any actual sharing in the last 6 months a significant proportion would still be prepared to share injecting equipment within certain situations. The preparedness to share injecting equipment was seen to be influenced by such factors as social distance, sex and length of time injecting. It is suggested that even in situations where drug injectors may have modified their behaviour in the direction of lower levels of reported sharing, a propensity to share may remain. This suggests the continuing need to provide injectors with easy access to sterile injecting equipment; in addition, services working with injecting drug users may need to focus not only upon actual sharing behaviour but also upon what we have described here as the preparedness to share. Indeed, the latter dimension should stand as a warning to services of the potential for sharing injecting equipment to increase in the future.

HIV/AIDS-related behavior change among injecting drug users in different national settings

OBJECTIVES

To identify factors associated with effective AIDS behavior change among injecting drug users (IDU) in different national settings.

DESIGN

Cross-sectional surveys of IDU, with determination of HIV status. Trends in city HIV seroprevalence among IDU also used to validate effectiveness of behavior change.

SETTING AND PARTICIPANTS

Subjects recruited from drug-use treatment programs and outreach efforts in Bangkok, Thailand (n = 601), Glasgow, Scotland (n = 919), New York City, USA (n = 2539), and Rio de Janeiro, Brazil (n = 466).

RESULTS

Evidence for the effectiveness of self-reported risk reduction was available for all cities. Univariate followed by multiple logistic regression analyses were used to identify factors associated with self-reported AIDS behavior change. Separate analyses were conducted for each city. Talking about AIDS with drug-using friends was significantly associated with behavior change in all four cities. Talking with sex partners about AIDS, educational level, knowing that someone can be HIV-infected and still look healthy, and having been tested previously for HIV were each significantly associated with behavior change in three of the four cities.

CONCLUSIONS

Despite the substantial differences in these national settings, there were common factors associated with effective risk reduction. In particular, risk reduction appears to occur through social processes rather than through individual attitude change. HIV prevention programs need to explicitly incorporate social processes into their work.

Mobility of Scottish injecting drug users and risk of HIV infection

Nine hundred and nineteen injecting drug users (IDUs) were interviewed in Glasgow, Scotland during 1990 and 1991, as part of a wider study of HIV risk behaviour, about their injecting and sexual behaviour outside the city in the previous two years. Forty-five percent of respondents injected outside Glasgow, 6% shared needles and syringes (n/s) and 20% had sexual intercourse. Much activity occurred outside Scotland but mainly within the UK, particularly London. Predictors of n/s sharing outside Glasgow during the previous two years included current injecting with and passing on of used n/s and sexual intercourse with casual partners. Predictors of sexual behaviour outside Glasgow included passing on used n/s, having sexual intercourse with casual partners and, for females, engaging in prostitution. Glasgow IDUs are a highly mobile group and although HIV prevalence remains low within this population, considerable potential for importation/exportation of HIV and other bloodborne and sexually transmitted infections exists. Further work is required to establish why IDUs travel to, and engage in high-risk activities in locations outside their home environment, and detailed data about activities such as frequency of condom usage and n/s cleaning practices need to obtained. While there is a widespread network of services for IDUs in the UK, information provided usually relates to local services and may not fully address the needs of this mobile population. Therefore, we recommend that IDUs be provided with details of facilities such as n/s exchange schemes and drug-treatment establishments in centres to where they most commonly travel.

Comparison of four survey methods designed to estimate the prevalence of HIV among female prostitutes who inject drugs

In Glasgow, during the period January 1990 to December 1992, 4 different methods were used to determine HIV prevalence among female prostitutes who inject drugs: the surveillance of prostitutes undergoing voluntary named tests, an unlinked anonymous survey of prostitutes attending a health care drop-in centre, a community-wide voluntary anonymous survey of injecting drug users including female prostitutes, and a voluntary anonymous survey of female prostitutes recruited in Glasgow's red-light area. HIV prevalence varied from 1.2 to 4.7% though overlapping confidence intervals indicated no significant differences. A comparison of each approach leads the authors to suggest that the former 2 methods which are relatively inexpensive should be conducted, if possible, on high risk groups such as prostitutes and injecting drug users on a continuous basis. If these indicate HIV rates which are stable and less than 5%, implementation of more sophisticated voluntary anonymous approaches need only be done every 3 to 4 years. However, if rates are unstable and/or greater than 5% then such surveys should be initiated more frequently, perhaps biannually.

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.

HIV risk behaviours among female prostitute drug injectors in Glasgow

This paper focuses upon HIV-related risk behaviours of 51 female drug injecting prostitutes, interviewed as part of a serial cross-sectional study of injecting drug users in Glasgow. Forty-five per cent injected with used needles and syringes in the 6 months prior to interview. Condom use in private sexual relations was low with only 9% of those with primary partners and 22% of those with casual partners reporting consistent use of condoms with these partners. In contrast, use of condoms for all commercial sexual encounters was almost universal. Prevalence of HIV was 2.2%. Despite this low prevalence, we conclude that the level of injecting-related and private sexual risk behaviours reported here requires the continuing monitoring of drug injecting prostitutes in Glasgow.

HIV prevalence and HIV risk behaviour among injecting drug users in London and Glasgow

This paper reports on the British findings from a cross-national study of HIV prevalence and HIV risk behaviour among 1,037 injecting drug users (IDUs) recruited from a variety of treatment- and community-based settings during 1990. Confirmed HIV saliva test results show 12.8% (63) of London respondents and 1.8% (8) of Glasgow respondents to be HIV antibody positive. Among London respondents, a higher rate of prevalence was found in those with no experience of drug treatment. A greater proportion of Glasgow respondents (68%) than London respondents (47%) reported sharing used injecting equipment in the 6 months prior to interview. The majority (88% in both cities) attempted cleaning borrowed equipment, although less than a third (31% in London and 30% in Glasgow) usually used bleach. The majority of respondents (71% in London and 82% in Glasgow) were sexually active with partners of the opposite sex in the last 6 months, and respondents had a mean number of 2.4 non-commercial sexual partners in London and 2.1 in Glasgow. Levels of reported condom use were comparable with reports in the heterosexual population as a whole, with 70% of London respondents and 75% of Glasgow respondents never using condoms with primary partners, and 34% of London and 52% of Glasgow respondents never using condoms with casual partners. Half (48%) of London respondents and 42% of Glasgow respondents reported sexual intercourse with non-injecting private sexual partners, while 14% of female respondents in London and 22% in Glasgow had engaged in prostitution. Levels of risk-taking in each of the two cities indicate the potential for further transmission of HIV among drug injectors, and their sexual and sharing partners.

Estimating the population prevalence of injection drug use and infection with human immunodeficiency virus among injection drug users in Glasgow, Scotland

Although data on the prevalence of injection drug use are an essential prerequisite for estimating the number of individuals infected with the human immunodeficiency virus (HIV), there have been few attempts to utilize statistical methods of population estimation based on multiple data sources. Data on 3,670 cases (2,866 individuals) were obtained from the HIV test register, drug treatment agencies, police records, and needle and syringe exchanges in Glasgow, Scotland, in 1990. Log-linear analysis was used to model the number of individuals in each of the sources. The model incorporating dependency among the three health care agencies (HIV test, drug treatment, and needle exchange) and independence of the police sample fitted the data well, with a residual chi 2 value of 2.9 (6 df). The expected value of the missing cell corresponding to absence from all four samples was 5,628, yielding an overall estimate of 8,494 injectors (95% confidence interval (CI) 7,491-9,721), for a prevalence rate of 1.35% for people aged 15-55 years in Glasgow during 1990. The high ratio of known to unknown injectors (1:2) resulted from the extensive coverage of known injectors and the relatively high level of overlap between the combined health care agency sample and the police sample. While further analysis demonstrated that the probability of appearing in the four samples varied by age and sex, heterogeneity in the population did not affect the choice of model or substantially alter the estimates for the total number of unknown injectors. A concurrent study of a community-wide sample of 503 injectors resulted in an HIV prevalence rate of 1.1% (95% CI 0.4-2.5%). The results of these studies were combined to produce a further estimate of 93 HIV-infected current injectors in Glasgow (95% CI 33-214).

Female streetworker--prostitutes in Glasgow: a descriptive study of their lifestyle

The objective of this study is to describe the lifestyle of a group of female prostitutes. The collection of information was achieved by: (i) using a self administered questionnaire; and (ii) conducting conversational type interviews. Of 85 women attending a health care drop-in centre for female street prostitutes in Glasgow, 63 completed the questionnaire and 72 participated in conversational interviews. For 63 women the mean age of commencement of prostitution was 21 years. Fifty-one (81%) were injecting drug users, their most commonly used drugs being heroin and temazepam. They worked a mean of 5.5 evenings per week and provided sexual services to a mean of 6.4 clients per working day. Less than half of these services were estimated to be vaginal intercourse. While 59/60 women indicated that they always used condoms during vaginal intercourse, this only applied to commercial sex; only 8/47 (17%) always used condoms with their regular sexual partners. Unconventional sexual services, e.g. voyeurism and physical abuse, were commonly provided and clients were often violent. A typical female streetworking-prostitute in Glasgow was aged 25, unemployed, an injecting drug user and had commenced prostitution 4 years before. Her knowledge of HIV/AIDS was good and for vaginal intercourse she almost always used condoms with clients, though probably not with her regular partner. Her main concern was likely to be violence from clients.

Discriminating needle exchange attenders from non-attenders

In 1990, approximately 1500 of Glasgow's estimated 9400 injecting drug users attended the city's four needle and syringe exchanges. In the same year, a multisite and citywide strategy was used to interview an estimated 5% sample of the city's injectors using an internationally agreed WHO structured schedule. Of the 503 injectors who participated in the study 54% (n = 272) had made use of exchanges in the last 6 months (including 165 injectors recruited from exchanges), while the remaining 46% (n = 231) had not. Twenty-seven variables were entered into a stepwise discriminant analysis to predict group membership (attenders vs. non-attenders). Fourteen variables emerged in the final discriminant function, which explained 17.3% of the variance between the two groups. Comparison of the model to random classification of cases resulted in a third fewer cases being wrongly assigned. Needle exchange attenders report injecting fewer drugs, less injecting with and passing on of used equipment and greater use of condoms with casual partners, compared to non-attenders. They also had greater knowledge of AIDS and had made and maintained more harm reduction changes, although they were less likely to have received treatment than non-attenders. The finding that attenders were less likely to inject with or pass on used needles and syringes is discussed in the context of availability of clean equipment and perception of risk. Variables reflecting lifestyle such as housing, employment and prison experience were not found to have any discriminatory power.

Prison experience of injecting drug users in Glasgow

Five hundred three injecting drug users in Glasgow recruited by a multisite and citywide sampling strategy were questioned regarding their drug-taking behaviour during episodes of custody over the six months prior to interview. Fifty-two percent had been in custody during the past 6 months, 16% of these had injected while in custody. Of these 73% borrowed injecting equipment and 78% handed on used equipment to others. All those who shared, cleaned their injecting sets before use. Over half of those who injected had a source of new sets. While the potential exists for spread of HIV among drug users while in custody there is clear understanding among them of the route by which the virus is spread and also the will to prevent it.

Mortality among injecting drug users: a critical reappraisal

STUDY OBJECTIVE

The aim was to quantify all cause mortality among injecting drug users.

DESIGN

This was a retrospective analysis of 1989 data on injecting drug users and mortality obtained from three independent agencies: the Procurator Fiscal's Office, the General Register Office, and the Scottish HIV-test register.

SETTING

Greater Glasgow, Scotland.

SUBJECTS

Drug injectors, estimated population 9424.

MAIN RESULTS

81 names were found using the three sources to identify deaths. After removing duplicates, 51 deaths were found. This represented a mortality rate of 0.54% in the estimated population. Among female injectors the mortality rate was 0.85%, significantly higher than the rate of 0.42% among male injectors (95% CI for the true difference in mortality rates between female and male injectors was 0.31%-0.55%). Over 90% of deaths were attributed to overdose or suicide. Although AIDS caused only one death, 19% of cases (5/27) whose HIV antibody status could be ascertained were positive. The mortality rate among HIV positive injectors (3.8%) was significantly higher than among HIV negative injectors (0.49%).

CONCLUSIONS

Comprehensive coverage using three data sources revealed a far greater annual number of all cause deaths among injectors than would have been expected from previous research. The observed mortality rate was lower than in previous studies where the denominators used to calculate rates had an element of underenumeration. For the foreseeable future it is unlikely that AIDS will have much impact on mortality among injectors in Glasgow, because of the low prevalence of HIV infection among injectors in the city, and because HIV positive injectors are dying for reasons other than AIDS; rather, overdose and suicide will continue to be the main causes of death.

Modeling the behavior and attributes of injecting drug users: a new approach to identifying HIV risk practices

The behaviors and attributes of 503 Scottish injecting drug users were modeled using the linear structural equations program LISREL. Drug use was directly related to prison experience, sexual activity, sharing of injecting equipment, and prostitution. Although the prevalence of HIV among the sample was low (2.0%), the pattern of risk behaviors observed in the data affords potential for future spread of the virus. Harm reduction measures taken by injectors in response to the threat posed by AIDS were inversely related to drug use but, more encouragingly, directly related to awareness of the disease, treatment for drug use, and prostitution.

HIV testing among injecting drug users in Glasgow

The use of saliva rather than blood for epidemiological studies of HIV prevalence, especially among injecting drug users, has several practical advantages. In a cross-sectional, behavioural and prevalence study among drug users in Glasgow during 1990, salivary samples were therefore obtained by the use of salivettes. Such samples were requested for anonymous anti-HIV testing from 498 persons in locations varying from residential rehabilitation centres to the open streets. Of this number, 35 refused to give a sample, resulting in a compliance rate of 93%. Of the 463 salivettes received by the laboratory, eight were found to be dry. Of the remaining 455 specimens, eight were found to be positive for HIV-1 antibody by means of an IgG antibody capture ELISA, so giving a prevalence rate of 1.8%. The results of testing saliva and blood spot samples collected at the same time on filter paper from 98 persons for HIV-1 antibody were 100% concordant. The study confirms the experience of others that specimens of saliva are easy to collect under variable conditions by non-medical staff and demonstrates that the salivette can provide an HIV antibody test result the same as that obtained from a blood spot. The prevalence of HIV antibody determined in this study is similar to that of other studies taking place in the city during the same period of time.

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

OBJECTIVE

To use research and surveillance studies in Glasgow (Scotland, UK) to estimate the number of current injectors infected with HIV, the total number of injectors infected up to the end of 1990 and the recent incidence of infection.

DESIGN

(A) Prevalence of injecting drug use was estimated using log-linear modelling. (B) Prevalence of HIV infection was determined from voluntary testing of a community-wide sample of injectors. (C) The number of infected current injectors was predicted by combining the distributions generated by (A) and (B). (D) Data on known HIV-positive injectors were used in conjunction with (C) to forecast the cumulative number of infected injectors.

RESULTS

The number of current injectors was estimated to be 9400; the prevalence of HIV infection among 447 injectors recruited to the HIV prevalence study during 1990 was 1.1%. From these data, the number of HIV-positive current injectors in 1990 was estimated to be between 52 and 138. Between 1985 and 1990, 110 known HIV-positive injectors were registered or received treatment in Glasgow for HIV-related diseases; the total number of cases estimated to have occurred during this period was between 110 and 300. The incidence of infection in Glasgow during 1990 was likely to have been low in light of the finding that only one case in the prevalence study had not previously been diagnosed HIV-positive.

CONCLUSIONS

Linkage of datasets from a variety of sources and studies has enabled the substantial refinement of estimates of the number of injectors and the proportion infected with HIV in Glasgow up to 1990.

Reduction in needle sharing among community wide samples of injecting drug users

Evidence of reduced levels of needle sharing among injecting drug users (IDUs) has largely been confined to IDUs attending needle exchanges or receiving treatment. In this paper we present the results of a serial cross-sectional study of needle sharing conducted in Glasgow using a multisite sampling strategy. Of the estimated 9400 IDUs in the city, 503 were interviewed in 1990 and 535 in 1991. The proportion of IDUs reporting injecting with, or passing on used needles and syringes in the last 6 months fell significantly as did the number of individuals from whom equipment was received or passed on to. The impact of this level of sharing has been limited in terms of HIV transmission; the prevalence of HIV among the 1990 sample was 2.0% and 1.1% for the 1991 sample. However, the fact that third of IDUs in Glasgow continue to inject, even occasionally, with used equipment gives cause for concern in view of the other pathologies known to be associated with poor injecting hygiene.