Search

Background: Epidemiological studies among drug users are often based on retrospective self-reports. However, among others, memory failure, being under the influence of drugs, psychopathology, misunderstanding of questions and socially desirable answering may generate inaccurate reporting.Methods: This study validated self-reported current (methadone dosage) and medium-term (main location of methadone dispensing and frequency of methadone programme attendance over the previous 4-6 months) aspects of methadone treatment in the Amsterdam AIDS cohort study among drug users, using data of the Central Methadone Register. In addition to descriptive measures, logistic regression analysis was used (adjusted for intra-individual correlation) to identify subgroups with incorrect reporting. Data collected at 4406 visits of 505 cohort participants were analysed.Results: Current methadone dosage was accurately reported (unweighted kappa [kappa]: 0.94, weighted kappa [kappa W]: 0.97). A low methadone dosage, short duration of school education and depressive or euphoric mood during the interview were significant and independent predictors of incorrect reporting of methadone dosage. For main location of dispensing kappa was 0.82, for frequency of programme attendance kappa was 0.53 and kappa W 0.87. There was a tendency to reporting the extreme answering categories. Infrequent programme attendance was the only significant predictor of incorrectly reporting frequency of programme attendance.Conclusions: Drug users are able to give valid self-reports in a setting where social desirability does not play an important role. The main reasons of incorrect reporting were impaired cognitive functioning, memory failure and misunderstanding of questions. [ABSTRACT FROM AUTHOR]

Objective: This study compares the quality of class I restorations made with the atraumatic restorative treatment (ART) technique and conventional class I amalgam restorations., Methods: The study was carried out among secondary school students in Mzuzu, Malawi. First-year students in 1987 who needed at least two class I restorations were selected. Based on a split-mouth design, each participant received both ART and conventional restorations. The 89 pairs of class I cavities were divided randomly into two groups, since two different cermet ionomer cement (CIC) filling materials were used. Impressions of the restorations and subsequent models were made shortly after restoration, after six months, one year, two years, and three years. The quality of the restorations was determined on the models following the US Public Health Service criteria. Bulk fracture, contour, marginal integrity, and surface texture of the restorations were recorded and evaluated separately. Survival rates were determined by the resultant score of all criteria., Results: Though conventional amalgam restorations performed better on all criteria, this difference was significant only for the contour criterion. The survival rates of ART restorations after three years (81.0%) were lower than those of amalgam restorations (90.4%) (P=.067)., Conclusions: The quality of ART class I restorations is competitive with that of conventional amalgam restorations.

Background: In order to demonstrate the feasibility of human immunodeficiency virus (HIV) infection and related risk behaviour surveillance in European prisons, a multicentre pilot study was undertaken., Methods: A cross-sectional survey was carried out in six European prisons (France, Germany, Italy, The Netherlands, Scotland and Sweden). Inmates were invited to complete a self-administered and anonymous questionnaire and to give a saliva sample in order to test for HIV antibodies., Results: Eight hundred and forty-seven out of 1,124 inmates participated in the survey (response rate 75%). Saliva from 817 inmates (73%) was collected and processed for HIV antibodies. Twenty-seven per cent reported that they had ever injected drugs and 49% of these reported they had injected whilst in prison. Eighteen per cent of inmates reported that they had been tattooed whilst in prison, which was found to be higher among injecting drug users (IDUs). One and sixteen per cent reported that they had ever had homosexual and heterosexual intercourse in prison respectively. The HIV prevalence among IDUs was 4% (versus 1% among non-IDUs) (p = 0.02). The proportions of inmates previously tested for hepatitis C and vaccinated against hepatitis B were 24 and 16% respectively., Conclusion: This survey demonstrates the feasibility of cross-sectional surveys in European prison inmates and highlights the importance of surveillance of HIV prevalence and related risk behaviour among inmates. The continuing high HIV prevalence and potential for HIV spread in prisons should encourage decision makers in implementing or enhancing harm reduction and education programmes and substance abuse treatment services in prison.

Mortality and morbidity between injecting drug users in Amsterdam (n = 624) and Baltimore (n = 2,185) are compared to generate a hypothesis about the role of different health care systems and drug user policies (universal care and harm reduction versus episodic care and criminalization, respectively). Overdose/suicide mortality was twofold higher in Amsterdam; no sufficient explanation was found. Other independent "risk factors" for overdose/suicide mortality were recent injecting, polydrug use, and HIV-seropositivity (especially with CD4 count < 200/mm3). High dose methadone maintenance was associated with lower mortality. Incidence of hospitalizations and emergency room visits was substantially lower in Amsterdam, suggesting that higher accessibility to primary care in Amsterdam lowers (inpatient) hospital visits and presumably societal costs.

Aims: To determine levels of injecting drug use and sexual risk behaviours in injecting drug users during and immediately following imprisonment in The Netherlands., Design, Setting and Participants: Cross-sectional survey of drug injectors attending methadone clinics, a sexually transmitted disease clinic and a central research site in Amsterdam. The mean age of the 188 participants was 35 years, 78% were male and 34% had HIV antibodies., Measurements: Self-reported drug use and sexual behaviours during the last period of imprisonment in Dutch prisons within the previous 3 years and injecting drug use in the week following release from prison., Findings: A period of imprisonment in the preceding 3 years was reported by 188 (41%) of 463 interviewed drug injectors. The mean duration of last imprisonment was 3.6 months. Any use of cannabis, heroin or cocaine during imprisonment was reported by 55%, 37% and 20%, respectively. Five injectors (3%) admitted to having injected in prison, but no sharing of needles and syringes was reported. Vaginal or anal sex was reported by two (1%) of the men and none of the women. Relapse to drug injecting during the week following release from prison was reported by 78/186 (42%) participants, in most cases (34%) at the very first day of release. Drug use behaviours during imprisonment were similar for those who were designated current injectors at the time of imprisonment and those who were not, but injecting in the first week following release from prison was far higher among 'current' injectors (63%) than among those who were not (11%)., Conclusions: Contrary to findings from other countries, low levels of HIV risk behaviours occur among imprisoned drug injectors in The Netherlands. Intra-prison HIV preventive measures should be considered taking into account the nationally, regionally or locally varying conditions within the existing prisons.

Aims: To evaluate the Methadone Dispensing Circuit in Amsterdam by identifying determinants of methadone dosage and client characteristics in the different types of methadone programmes., Design and Participants: Four hundred and forty-four participants of a cohort study of drug users in Amsterdam who had consented to link data of the Central Methadone Register to the cohort data., Findings: From 1985 to 1994, methadone dosage increased from 41 to 59 mg/day. The mean methadone dosage was higher for ethnic West Europeans, Germans, older drug users, HIV-positive drug users, those with a longer duration of prostitution, current injectors, those with a longer duration of injecting, longer duration of methadone use, higher frequency of being dispensed methadone and clients of the prostitutes' and foreigners' outpatient clinic. For clients of the general practitioner, at the police station and in prison the methadone dosage was lower. We found different sets of client characteristics in those receiving methadone at the methadone outpost, the methadone bus, the prostitutes' and foreigners' outpatient clinic, the general practitioner and the outdoor addiction clinic., Conclusions: These results indicate that the Amsterdam system is highly differentiated in a way that is largely concordant with the intended general policy on methadone treatment.

Aim of this study was to assess the cumulative incidence of HIV-infection, AIDS and pre-AIDS death in the population of injecting drug users (IDU) in Amsterdam. By assuming equivalence, between a cohort of IDU and the IDU population, of the ratios of incidences of AIDS and pre-AIDS death to the number of HIV positive persons giving rise to these incidences, the numbers of HIV positive persons and pre-AIDS deaths in the population could be calculated, given that other parameters were known. Cohort study data on HIV prevalence and incidences of HIV infection, AIDS, and pre-AIDS death, were combined with national AIDS surveillance data. As of 1 October 1994, the estimated cumulative number of HIV positive IDU in Amsterdam was approximately 1280, far higher than a recent back-calculation estimate. Of the 1280, 204 HIV positive IDU had been diagnosed with AIDS, while about 270 had died pre-AIDS. The HIV prevalence of IDU residing in Amsterdam that were still alive and free of AIDS was hence estimated at around 800. Since the incidence of pre-AIDS death and AIDS exceeded the number of seroconversions during the past four years, the HIV epidemic among IDU in Amsterdam appears to be dwindling. A lower bound of the number of HIV positive IDU being alive, AIDS-free and living elsewhere in the Netherlands was roughly estimated at 600. Because of untimely deaths, only a limited number of HIV positive IDU can be expected to be diagnosed with AIDS in the future. Since these estimates are based upon some rather bold assumptions, they should be interpreted with caution and require further validation by independent sources.

Background: As a consequence of the human immunodeficiency virus (HIV) epidemic, which continues among illicit drug users, high rates of HIV-associated morbidity are believed to exist. This study focuses on hospitalizations of drug users and on the relative contribution of drug users to the total burden of inpatient hospital care in Amsterdam., Methods: During the years 1990-1992, data were collected on hospital admissions of injecting and non-injecting drug users to all 10 general and university hospitals in the city of Amsterdam (population 700 000; estimated number of drug users 5800). Total number of admissions, total days of hospitalization and primary discharge diagnoses according to HIV serostatus and sex were determined for drug users., Results: A total of 1293 admissions were recorded among 842 hospitalized drug users. Between 53% and 77% of days of hospitalization attributable to drug users related to HIV-infected patients, and at least 23% to patients with AIDS. In the 20-44 age group of the Amsterdam population, 5.1% of days of hospitalization for men and 1.8% for women could be attributed to drug users, or about twice as much as could be expected from their numbers alone. For all ages, the contribution of drug users to hospitalizations was 1.2% for males, 0.4% for females, and 0.8% for all. Drug users occupied an average of 19 hospital beds, corresponding to an annual cost of US$ 3.1 million. Due to underreporting of admissions, these figures should be considered lower bound estimates., Conclusions: On the total scale of inpatient hospital expenditure in Amsterdam, the contribution of illicit drug users appears to be small.

The impact of human immunodeficiency virus (HIV) infection and other risk factors on mortality was studied in a cohort of Dutch injection drug users and drug users who did not inject. Participants were recruited between 1985 and 1992 and followed up through 1993. Vital status was ascertained through repeat visit information, supplemented by population register data. A total of 77 deaths were recorded among 632 drug users, for a mortality rate per 1,000 person-years of 7 for HIV-negative noninjection drug users, 18 for HIV-negative injection drug users, and 64 for HIV-positive injection drug users. In multivariate analyses, limited to injection drug users, a positive HIV serostatus, age above 40 years, and using benzodiazepines several times daily were significantly associated with an elevated risk of death, both for death from all causes and for death preceding acquired immunodeficiency syndrome (AIDS) diagnosis (pre-AIDS). For pre-AIDS death, the adjusted relative risk associated with HIV infection was 2.2 (95% confidence interval 1.3-3.7). Only 38% of HIV-infected injection drug users who died were diagnosed with AIDS. However, 76% of HIV-infected injection drug users who died without AIDS diagnosis had evidence of immunosuppression (CD4 count < 500/microliters). Daily use of methadone and participation in needle and syringe exchange schemes were not associated with lower mortality rates. This study illustrates in a group of injection drug users with a 30% HIV seroprevalence and a high background mortality the profound influence on mortality that HIV infection has gained.

Objective: To investigate whether notifying injecting drug users (IDU) of their positive HIV serostatus contributes to suicide and overdose mortality risk., Design: Members of a cohort of IDU, recruited since December 1985, who first learned their HIV serostatus after study entry but before December 1992, were studied for incidence of deaths due to suicide and overdose., Methods: Incidence of mortality due to suicide/overdose was calculated from date of first HIV test result disclosure until the end of follow-up or diagnosis of AIDS., Results: Eighty-six HIV-positive and 252 HIV-negative IDU were included with median follow-up times of 4.3 and 4.0 years, respectively. Seven suicides and 10 deaths from overdose were recorded. High suicide/overdose risk shortly after test result notification was not found among HIV-positive IDU. Only one out of eight HIV-positive IDU who died of suicide/overdose died within 6 months of first disclosure. The overall suicide/overdose mortality rate was higher for HIV-positive than HIV-negative IDU; the rate ratio being 2.46 [95% confidence interval (CI), 0.95-6.39] or 2.04 (95% CI, 0.77-5.39) after control for confounders., Conclusions: Notifying IDU of their positive HIV serostatus does not appear to lead to a sudden and substantial rise in suicide/overdose deaths. Although death from suicide/overdose is more common among HIV-positive than HIV-negative IDU, this difference is likely to result from factors other than test result disclosure. Therefore, provided that appropriate counselling is offered, we see no reason to discourage voluntary HIV test result notification for fear of inducing suicide in HIV-infected IDU.

The aim of the study was to assess prevalence and incidence of hepatitis B virus (HBV) infection among heterosexual men and women with multiple partners attending a sexually transmitted disease (STD) clinic and to establish risk factors of HBV infection in order to consider immunisation for those subjects. A prospective study of heterosexual men and women selected on having multiple partners and presenting to an STD clinic as new patients was carried out from October 1987 through December 1989. Follow-up continued until December 1990 at the STD clinic of the Municipal Health Service of Amsterdam. Five hundred ninety-eight men and women entered the study. More than 70% of both women and men had had commercial sexual partners in the last 5 years. Three hundred eighty-one participants were born in HBV low endemic countries, 205 came from HBV intermediate endemicity regions. The prevalence of HBV markers in both men and women from low endemic regions was 10%, and for men and women from middle endemic regions 42% and 19%, respectively. Logistic regression analysis showed that number of years involved in commercial sex was an independent risk factor in male participants from HBV low endemic regions (odds ratio [OR] 1.10 per year) and for women sexual contact with men at high risk of HBV infection (OR 2.59).(ABSTRACT TRUNCATED AT 250 WORDS)

Objective: To quantify mortality without AIDS diagnosis (pre-AIDS death) among HIV-infected injecting drug users (IDU) and to compare it with that among homosexual men., Setting: Municipal Health Service in Amsterdam, The Netherlands., Design: HIV-infected participants of a cohort of homosexual men (recruited since 1984) and a cohort of IDU (recruited since 1985) were followed up to investigate the occurrence of AIDS and pre-AIDS death up to 1 October 1992. Both seroprevalent and seroconverted participants were included., Methods: Product-limit estimates of cumulative AIDS incidence and cumulative pre-AIDS mortality were calculated for a competing risks model., Results: Of 455 HIV-infected homosexual men, 127 developed AIDS and two died without a diagnosis of AIDS during follow-up; 31 out of 279 HIV-infected IDU were diagnosed with AIDS and 33 died without an AIDS diagnosis. After 6.5 years of follow-up an estimated 43.7% of the homosexual men had been diagnosed with AIDS and 0.7% had died without an AIDS diagnosis, while 32.7% of the IDU had been diagnosed with AIDS and 19.8% had died without an AIDS diagnosis., Conclusions: After 6.5 years of follow-up one-fifth of a group of HIV-infected IDU had died without being diagnosed with AIDS. This phenomenon seriously limits the number of HIV-infected IDU that may ever be diagnosed with AIDS and should be considered by HIV infection epidemic modellers. The new case definitions for AIDS will limit the number of recorded cases of pre-AIDS death.

Objective: To determine trends in commercial sexual risk behaviour among drug-using prostitutes in Amsterdam after local and national prevention campaigns began in 1987., Design: A subgroup of 281 drug-using prostitutes was selected from a comprehensive, open cohort study of drug users in Amsterdam., Methods: Cross-sectional (at intake) and within-person trends in sexual behaviour were evaluated. Person-time analysis was used to determine trends in incidence of sexually transmitted disease (STD)., Results: From 1986 to 1992, 'always' use of condoms in the 6 months preceding intake increased from 21 to 58% (P < 0.001) and the number of commercial contacts declined from 84 to 64 per month (P = 0.06). Consequently, the mean number of unprotected commercial contacts declined from 26 to nine per month (P < 0.001). Temporal trends within individual prostitutes from visits 1 to 8 (mean interval between visits, 4 months) showed a somewhat larger risk reduction than the cross-sectional trends. From 1989 to 1992, the STD incidence declined from 61 to 40 episodes per 100 person-years (P = 0.06). Prostitutes residing in Amsterdam for shorter time periods reported more STD and a relatively small core group reported the majority of STD episodes. At intake, when < 10% of all participants knew their HIV serostatus, HIV-positive prostitutes reported significantly lower levels of condom use and more STD than HIV-negatives, while, after learning their serostatus, levels of condom use and the STD-incidence were comparable. Prevalent and incident HIV infections were not observed among non-injecting prostitutes., Conclusions: Drug-using prostitutes have reduced sexual risk behaviour. There is evidence for the effectiveness of HIV testing and counseling. At present, new infections among clients of drug-using prostitutes are expected to occur, although not on a large scale. Since the incidence of STD continues to be high, it is important to monitor the spread of HIV among heterosexuals, including prostitutes and their clients, closely.

An investigation into the prevalence of human papilloma virus (HPV) infection, abnormal cervical cytology and the relationship between HIV- and HPV infection was done in a group of intravenously (IV) and non-IV drug-using prostitutes. From July 1991 through May 1992, hard drug-addicted prostitutes attending a sexually-transmitted-disease (STD) clinic in Amsterdam were recruited. A questionnaire was administered to obtain demographic characteristics, and medical and STD history. Apart from routine STD examination, cervical scrapes for cytology and samples for HPV DNA detection by polymerase chain reaction (PCR) were collected. Some of the women included in this study also participated in HIV studies among drug users. Their data on HIV- and immunologic status could be combined. A total of 121 women entered the study; 25 women were HIV-seropositive, 44 women were HIV-negative, and the HIV status of 52 women was unknown. All 25 HIV-positive women had normal Pap smears, two of the 44 HIV-negative women had a Pap smear III A, and in the HIV-unknown group, two women with Pap III A and one with Pap III B were found. Eight of the 25 (32%) HIV-positive women were HPV DNA-positive, three of the 44 (7%) HIV-negative women and 10/52 (19%) of the HIV-unknown group. Logistic regression analysis showed that in the total group, presence or cervical HPV DNA was associated with HIV infection (order ratio [OR] for HIV-positives 7.8, 95% confidence interval [CI] 1.8 to 34.6) and with diagnosis of condylomata acuminata at entry to the study (OR 7.5, 95% CI 1.5 to 36.5).(ABSTRACT TRUNCATED AT 250 WORDS)

Objectives: To study groups of prostitutes and clients of prostitutes in order (i) to determine HIV prevalence and sexual risk behaviour, (ii) to determine differences between samples recruited within and outside a clinic for sexually transmitted diseases (STD) and (iii) to determine correlates of inconsistent condom use (ICU) among both groups., Design: Participants were interviewed and anonymously tested for HIV-antibody; approximately half were recruited at a clinic for sexually transmitted diseases (STD) and half at prostitute working places., Setting: An STD clinic and prostitute working places in Amsterdam in 1991., Subjects: 201 female prostitutes without a history of injecting drugs and 213 male clients of female prostitutes., Main Outcome Measures: antibodies to HIV, consistency of condom use in commercial vaginal contacts in the preceding 6 months., Results: HIV prevalence was low: three prostitutes (1.5%; 95% CI 0.5-4.6%) and one client (0.5%; 95% CI 0.1-3.3%) were infected. All three HIV positive prostitutes originated from AIDS-endemic countries, came to the Netherlands only recently and were recruited outside the STD clinic. Large differences between subgroups resulted from the two recruitment methods: while clients of prostitutes with relatively high risk behaviour were strongly represented among the STD clinic sample, high risk prostitutes were underrepresented in this sample. Consistent condom use (with 100% of contacts) was reported by 66% of prostitutes and 56% of clients of prostitutes. Inconsistent condom use was found to be high among prostitutes who had migrated from Latin America and among migrant clients of prostitutes., Conclusions: When monitoring HIV infection one must take into account imported cases. HIV prevention efforts should be particularly focused at prostitutes from Latin America and at clients of prostitutes who migrated to the Netherlands.

To assess risk factors for seroconversion to human immunodeficiency virus, the authors studied a cohort of human immunodeficiency virus-seronegative injecting drug users in Amsterdam, the Netherlands, between December 1985 and November 1991. The behaviors of 31 seroconverters were compared with those of 202 seronegative injecting drug users (controls). Three independent risk factors for seroconversion were found in logistic regression: 1) living greater than 10 years in Amsterdam (odds ratio (OR) = 2.45, 95% confidence interval (CI) 1.09-5.53); 2) first injection less than or equal to 2 years ago (OR = 3.43, 95% CI 1.20-9.81); and 3) injecting mainly at home (OR = 0.39, 95% CI 0.18-0.88). No evidence was found that receiving daily methadone treatments at methadone posts and obtaining new needles/syringes via the exchange program were protective. However, the data suggest that exchanging needles may have been protective at the start of this program. Influencing injecting drug users to modify behavior to prevent new infections appears to be very difficult, and it may, therefore, be important to increase preventive efforts targeted at the sexual partners of injecting drug users.

To assess heterosexual behavior of injecting drug users (IDUs) over time, we studied 174 IDUs with regard to their steady, casual, and commercial partners over a 1-year period. Within this year a large national AIDS prevention campaign had been implemented in the Netherlands. In addition, condom use was discussed with participants during various follow-up visits. We found a large turnover in IDUs who reported having steady, casual, or commercial partners. Limited change in sexual behavior occurred: the frequent use of condoms increased only with casual partners (from 30 to 49%), and the proportion of female IDUs working as prostitutes decreased (from 56 to 41%). At both measurements IDUs who knew that they were HIV infected used condoms more frequently with their steady partners and tended to report fewer casual partners than those who knew they were not infected. In addition, HIV-infected women tended to be less active in prostitution than noninfected women. We conclude that large-scale voluntary testing of IDUs, together with repeatedly discussing the risks of sexual transmission of HIV and the use of condoms as a preventive measure (counseling) may, at least among HIV-infected IDUs, result in some risk reduction. Health education to increase the use of condoms should also be directed at IDUs who at present do not have steady, casual, or commercial partners.

Objective: to assess whether male prostitution is an independent risk factor for HIV infection among male (intravenous and nonintravenous) drug users., Design: a cross-sectional study., Setting: various low-threshold methadone clinics and the sexually transmitted diseases clinic of the Municipal Health Service in Amsterdam and a drug-treatment centre in The Hague., Participants: 343 male intravenous drug users and 106 male non-intravenous drug users., Main Outcome Measures: characteristics concerning drug use behaviour, sexual behaviour, and sociodemography, related to prostitution and HIV-antibodies., Results: of the 449 study participants, 88 (20%) reported a history of prostitution; no differences were found between intravenous and non-intravenous drug users. Younger age, West German nationality, and having had private homosexual sex contacts, were independent predictors of a history of prostitution. Independent predictors of HIV infection were (1) longer residency in Amsterdam; (2) having had predominantly homosexual private sex contacts; (3) longer duration of intravenous drug use; and (4) frequent needle sharing., Conclusion: no evidence was found to suggest that male prostitution in itself contributed to the risk of HIV infection.

In determining the effectiveness of AIDS preventive measures among heterosexuals, trends in visits to two clinics for sexually transmitted diseases (STD) in Amsterdam between 1982 and 1989 are described. Also, data on sexual behaviour are presented that were collected in a sample of 635 heterosexual women and 947 heterosexual men at one of the clinics between September 1986 and December 1988. In 1987, when in The Netherlands for the first time extensive publicity was given to the risk of heterosexual transmission of the human immunodeficiency virus, the numbers of male and female heterosexual attenders started to decline. Exceptions to this general decline were men of Turkish nationality and foreign prostitutes, each group showing a continuing increase. At the same time, the numbers of customers reported by prostitutes in the sample declined markedly between 1986 and 1988, from a median of 35 to 15 per month (p = 0.001). Condom use with casual contacts generally increased in the sample period. We conclude that the publicity given to "heterosexual AIDS"--contributed to by the national AIDS prevention campaign--apparently led to a considerable decrease in the number of risky contacts of heterosexuals in Amsterdam in 1987 and 1988. This does not seem to apply to men with Turkish nationality. In 1989 a change appeared in several subgroups when the number of visitors started to rise. Also, the probability of an STD diagnosis increased in male attenders. This may indicate a change in the tendency towards safer sexual behaviour.

To determine if behavioral changes in intravenous drug users in Amsterdam have retarded the HIV (human immunodeficiency virus) epidemic in this group in recent years, we report that: HIV-antibody seroprevalence in annual samples of injectors has been constant over the years 1986-89; HIV-antibody incidence in a cohort of injectors appears to have decreased from 1986 to 1987 and stabilized after that until 1989; acute hepatitis B incidence in all drug users in Amsterdam declined rapidly between 1985-89. It is concluded that changes in drug use behavior so far appear to have resulted in a stabilization of the epidemic among injectors, at a level with a still disturbingly high incidence rate of 5-6 per 100 person-years.

The prevalence, risk factors, and incidence of hepatitis C virus (HCV) infection were studied in a cohort of drug users in Amsterdam. In intravenous drug users, the seroprevalence was 74% (224/304) versus 10% (4/42) in nonintravenous drug users. Risk factors independently associated with HCV antibody seropositivity were history and duration of intravenous drug use and frequency of injections. Daily smoking of heroin in the previous 6 months was independently associated with the absence of HCV antibodies. Periods of fever, tiredness, and diarrhea in the preceding 6 months were associated with HCV antibodies even after correction for human immunodeficiency virus infection. The incidence rate of HCV infection appeared high and stable over the years 1986 to 1989. Thus, HCV infections are common among intravenous drug users and are mainly due to the intravenous use of drugs.

In order to assess the potential role of intravenous drug users (IVDUs) in Amsterdam in the heterosexual transmission of HIV, we studied the sexual behaviour of 243 male and female IVDUs with regard to their private ('steady' and 'casual') and commercial partners. The majority of the study group appear heterosexually active, especially female IVDUs, who often have commercial as well as one or more private partners. Vaginal contact is the most frequent method of sexual contact; condoms are used infrequently with private partners but much more frequently with commercial partners. A history of sexually transmitted disease is common, not only among IVDU prostitutes but also among IVDUs without a history of prostitution. IVDUs who know that they are HIV-infected reported fewer commercial partners and more frequent condom use with private partners than IVDUs who are negative or do not know their test result. We conclude that IVDUs may form an important source for heterosexual transmission of HIV. Voluntary testing of IVDUs on a large scale, together with intensive counselling, may slow down the further spread of HIV from infected IVDUs to their private and commercial partners, but is unlikely to stop heterosexual transmission completely.

In December 1985 we started a study to determine the prevalence and risk factors of HIV infection among drug users and drug-using prostitutes in Amsterdam. Recruitment took place at methadone posts (not drug-free; i.e. a low-threshold programme on which some drug users continue to use hard drugs, but at a lower level) and the weekly evening sexually transmitted diseases (STD) clinic for drug-addicted prostitutes. Three hundred and ten drug users have so far been tested and interviewed. Eighty-one per cent reported intravenous drug use; 83% of the 166 females and 15% of the 144 men reported prostitution. Female prostitutes practised mainly vaginal and orogenital intercourse and reported frequent use of condoms (89% of vaginal and 64% of orogenital contact). Male prostitutes practised mainly orogenital and manual contact. At entry 88 of the 310 (28%) were HIV-antibody-seropositive; 85 of these 88 were intravenous drug users and three were male homosexuals. HIV-antigen was detected in two seropositive and one seronegative intravenous drug-user. Antibodies to HTLV-I were found in four out of 308. Risk factors independently associated with HIV-antibody seropositivity among intravenous drug users were: frequency of borrowing used needle or syringe, date of first intravenous drug use, recent intravenous drug use, time living in Amsterdam and German nationality. Of medical history data, an attack of herpes zoster in the previous 5 years had the greatest value in the prediction of the presence of HIV antibodies (relative risk 20.90; 95% confidence interval 2.41-167.27).(ABSTRACT TRUNCATED AT 250 WORDS)

To assess the potential role of drug using prostitutes in the heterosexual transmission of human immunodeficiency virus (HIV), 117 prostitutes, recruited from December 1985 to November 1987 at a weekly evening sexually transmitted diseases (STD) clinic for drug using prostitutes only, were studied for the prevalence of HIV and STD. Intravenous drug use was reported by 96 (82%) of the women. Antibody to HIV was found in 35/117 (30%) women, all but one of whom had been using drugs intravenously. Most (73, 62%) of the prostitutes reported having had more than 2000 clients each in the preceding five years. In the six months preceding enrollment to the study they had practised mainly vaginal (106/117) and orogenital (82/117) intercourse; 90% (105/117) reported frequent use of condoms in vaginal intercourse and 65% (68/105) in orogenital intercourse. Despite frequent condom use, 81% (84/104) contracted one or more STD in this period. Considering the high incidence of HIV and STD and the finding by others that the presence of STD may facilitate transmission of HIV, we conclude that the potential for HIV transmission from these prostitutes to their clients (and vice versa) was clearly present.

We evaluated the impact of a needle/syringe exchange program among 263 drug users in the period December 1985 to April 1988. Participants in this study were asked about their risk-behavior at three different visits. We found no increase in the proportion injecting drugs or in the frequency of intravenous drug use. A strong decrease in borrowing and lending of used needle/syringes was found and this behavioral change was not dependent on learning human immunodeficiency virus (HIV) serostatus. Although use of the exchange program increased over time, reduction in needle sharing was mainly an effect of the study with only a limited impact of the exchange program. We conclude that ample provision of needles and syringes is an important starting point but in itself not enough to produce the necessary drastic change in risk behavior. Intensive counseling of the drug user is also needed.