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National Research Council (US) and Institute of Medicine (US) Panel on Needle Exchange and Bleach Distribution Programs. Proceedings Workshop on Needle Exchange and Bleach Distribution Programs. Washington (DC): National Academies Press (US); 1994.

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Proceedings Workshop on Needle Exchange and Bleach Distribution Programs.

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Evaluation of the Needle/Syringe Exchange in Amsterdam, the Netherlands

Anneke Van Den Hoek and Roel Coutinho

Municipal Health Service, Department of Public Health and Environment, The Netherlands

AIDS and HIV in the Netherlands and Amsterdam

Through June 1993 a cumulative total of 2678 cases of AIDS have been reported in the Netherlands (circa 15 million inhabitants). Homosexual men are the most important risk group (78%), followed by injecting drug users (9%); 93% of the cumulative AIDS cases are men. In 1992 481 new cases were diagnosed and in 1991 437. Most of the AIDS cases in the Netherlands were reported from Amsterdam (700,000 inhabitants).

The total number of HIV infected persons in the Netherlands is estimated at 6,000-10,000. In Amsterdam the total number of homosexual men between 18 and 55 is estimated at 20,000 of whom 2,000-4,000 are infected with HIV. The number of drug users in the city is estimated at 7,000 of whom approximately 800 are HIV infected.

Background Information on Amsterdam Drug Policy

The estimate of the number of hard drug users in Amsterdam is based on a capture-recapture method and is a year prevalence. The estimated number of drug users staying on a regular day in Amsterdam is lower, approximately 5,500. This smaller number is due to the large number of foreign drug users who only stay briefly in Amsterdam.

Based on data of participants of the low threshold methadone programs, it is estimated that about 40% of the drug users in Amsterdam inject their drugs. The prevalence of the current injection of drugs among drug users differs according to country of origin: circa 40% of the Dutch drug users inject their drugs, compared to circa 70% of drug users of foreign origin (mainly German and South-European) and circa 5% of the ethnic drug users (from Surinam, the Netherlands Antilles, Morocco, and Turkey).

The assistance system for drug users in Amsterdam can be described in three phases: getting in contact, harm reduction and treatment.

Contact with drug users is made by 1) street corner workers, 2) physicians visiting drug users arrested in police-cells and 3) social nurses visiting all hospitalized drugs patients.

Through regular contact appropriate medical and social care can be given, which is considered "to be beneficial for drug users themselves and the society at large". This policy is called the harm reduction approach.

The main instrument for harm reduction (as long as the drug user is not able or willing to stop his/her drug use) is the large methadone program with a low level of threshold.

Another activity of the harm reduction approach is the needle and syringe exchange program, aimed at the reduction of the harm by injecting. This program was initially started in 1984-through an initiative of the drug users organization, the "Junkiebond"-to prevent hepatitis B, but was soon overshadowed by the more important goal of AIDS prevention. In 1985, 100,000 needles and syringes were handed out and this number has gradually risen to circa 700,000 in 1988 and to approximately one million in 1991 and 1992. In 1992, 92% of the distributed needles/syringes had been exchanged for a used needle/syringe. Presently Amsterdam has 14 needle exchange locations. It is possible to exchange needles and syringes from 10 a.m. till 4 a.m. the next day. During the night, two slot machines are in operation for purchasing syringes. Participation in the exchange program does not require identification or registration. For this reason, no information is available on the number of participants or on their demographic characteristics.

As the needle/syringe exchange program is a low threshold project, there is no registration or monitoring of clients. Evaluation of the impact of the exchange program on injecting behavior and the spread of HIV, has therefore mainly taken place in our cohort study on HIV infection and AIDS.

The Amsterdam Cohort Study on HIV Infection and AIDS Among Drug Users

The open cohort study started at the end of 1985. At that time only one drug user with AIDS had been reported in the Netherlands.

The aims of the study are

(a)

to study the prevalence and incidence of HIV infection and AIDS in relation to (changes in) drug use and sexual behavior;

(b)

to evaluate the impact of various HIV-prevention programs for drug users;

(c)

to study determinants of risky injecting and sexual behavior; and

(d)

to study the natural history of HIV infection.

Participants are recruited at methadone outposts, the special STD clinic for drug using prostitutes and by word of mouth. Eligible for the study are men and women who use or have used drugs, either by injection or otherwise. Blood samples for serology, virology and immunology are taken and participants are interviewed using a standard questionnaire which includes questions concerning clinical symptoms, medical history, lifestyle, use of oral and intravenous drugs (methadone included), and prostitution. Participants are asked to return for a follow-up visit every four months. Twenty five Dutch guilders are paid per follow-up visit to encourage continued participation.

Prevalence and Incidence of HIV Infection

Through July 1993 a total of 1,012 drug users had entered the study, 258 HIV positives and 754 HIV negatives. The HIV prevalence among drug users with a history of injecting drug use was approximately 30% (1 ) and remained more or less stable among new intakes in this group in following years (2 ). The annual HIV incidence per 100 person-years was 9.2 in 1986, varied between 2 and 5% in the years 1987-1991 (3 ) and was 2.5 in 1992. To date a total number of 52 seroconversions have occurred.

Risk Reduction and the Exchange Program

The first study on risk reduction among the participants (December 1985-April 1988) showed that during follow-up, a strong reduction in borrowing and lending occurred, and that this behavioral was not dependent on being informed of HIV serostatus (4 ). Over time, the use of the needle and syringe exchange program increased. However, reduction in needle sharing was not seen among new entrants to the study. Therefore, we concluded that the risk reduction observed during follow-up was mainly an effect of the study (with counselling), with the exchange program only having a limited effect.

The next study (5 ) looked into factors related to regular participation in the exchange program and the borrowing of syringes in 131 HIV seronegative current injecting drug users (1989-1990). A total of 29% of the users reported borrowing syringes in the past 4-6 months. Users at increased risk of borrowing are previous borrowers, long term moderate-to-heavy alcohol users, current cocaine injectors, and drug users without permanent housing. Regular clients of the syringe exchange, when compared with other injecting drug users, were found more often to be frequent, long term injectors. They borrowed slightly less often than other users, but this was not statistically significant, even after controlling for frequency of injecting or other potential confounders. These results suggest that 5 years after the start of the exchange program, drug use characteristics govern an individual injecting drug user's choice of exchanging or not exchanging. We concluded that it seems more important to direct additional preventive measures at injecting drug users with an increased risk of borrowing rather than at users who do not participate in the syringe exchange or who do so irregularly.

Another study (3 ) assessed risk factors for seroconversion to HIV, 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 > 10 years in Amsterdam (OR=2.45, 95%CI 1.09-5.53); 2) first injection < 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 obtaining new needles/syringes via the exchange program was protective. However, the data suggest that exchanging needles/syringes may have been protective at the start of this program. In the discussion of this finding we mentioned that this may be explained by an overall increased availability of needles/syringes, which enabled non-exchangers to more easily obtain new needles/syringes. Another explanation we mentioned was that, at the beginning of the program, a desire for risk reduction was the motive for exchanging, while later on exchanging became just a way to obtain injection equipment.

The methodological problems encountered in evaluating prevention programs are many. In general, little is known about the representativeness of the study sample of drug users. Furthermore, participants are self selected, and self-selection occurs again with respect to participation in the follow-up study. Self-reports on injecting and sexual behavior may be unreliable and are difficult to validate.

To evaluate the impact of prevention-programs, random allocation of drug users to the various programs would be the best study design. However, this allocation would be in conflict with the harm reduction policy which includes large accessibility of the programs for all drug users. Another problem in evaluating the impact of the programs on risk reduction is that drug users may attend programs for other reasons than risk reduction and the longer low threshold programs exist, the more this may be the case. On the other hand, health education messages have also reached drug users who do not want to use the needle and syringe exchange program to obtain clean needles and syringes and prefer to buy their needles and syringes at pharmacies and certain shops. These considerations may imply that the impact of a prevention-program cannot be assessed by studying differences in risk behavior between attenders and non-attenders.

Indeed, a last study (6 ) that studied serial, cross-sectional trends in injecting behavior from 1986 to 1992 showed that the proportion of drug users who reported borrowing and lending used injection equipment and re-using needles/syringes (in the 6 months preceding intake) continuously declined from 51% to 20%, from 46% to 10% and from 63 to 39%, respectively and that non-attenders of exchange programs reduced their risk behavior to the same extent as attenders. This finding explains why, in comparing attenders with non-attenders we were not able to demonstrate any impact of the exchange (and other prevention) programs on risk reduction*.

Conclusions

We conclude, therefore, that the evaluation of specific measures is difficult. Although we have not been able to demonstrate any impact of specific prevention measures, we think that all prevention activities taken together in Amsterdam (exchange programs, over-the-counter sales of needles/syringes by pharmacies, low threshold methadone programs, counselling projects, and information campaigns) have been responsible for the decline in high-risk injecting behavior.

However, it must be realised that a considerable number of drug users from time to time borrow an used needle/syringe and that transmission of HIV among drug users still occurs.

Literature

1.
van den Hoek JAR, Coutinho RA, van Haastrecht, van Zadelhoff AW, Goudsmit J. Prevalence and risk factors of HIV infections among drug users and drug using prostitutes in Amsterdam. AIDS 1988; 2(1):55-60. [PubMed: 3128998]
2.
Van Haastrecht HJA, van den Hoek JAR, Bardoux C, Leentvaar-Kuijpers, Coutinho RA. The course of the HIV epidemic among intravenous drug users in Amsterdam, The Netherlands. Am J Public Health 1991; 81:59-62. [PMC free article: PMC1404932] [PubMed: 1983918]
3.
Van Ameijden EJC, van den Hoek JAR, van Haastrecht HJA, Coutinho RA. The harm reduction approach and risk factors for HIV seroconversion in injecting drug users, Amsterdam. Am J Epidemiol 1992; 136:236-43. [PubMed: 1415145]
4.
Van den Hoek JAR, Van Haastrecht HJA, Coutinho RA. Risk reduction among intravenous drug users in Amsterdam under the influence of AIDS. Am J Public Health 1989; 79:1355-1357. [PMC free article: PMC1350173] [PubMed: 2782501]
5.
Hartgers C, van Ameijden EJC, van den Hoek JAR, Coutinho RA. Public Health Reports 1992; 107:675-682. [PMC free article: PMC1403720] [PubMed: 1454980]
6.
van Ameijden EJC, van den Hoek JAR, Coutinho RA. A substantial decline in injecting risk behavior among drug users in Amsterdam from 1986 to 1992, and its relationship to AIDS-prevention programs. Am J Public Health 1994; 84:275-281. [PMC free article: PMC1614996] [PubMed: 8296953]

Footnotes

*

For a part of the Amsterdam drug users the exchange program may have started too late, shown by the fact that in 1986 already 30% of the drug users in Amsterdam appeared to be infected with HIV. But for the rest of the Netherlands the exchange programs may have been in time. Recent HIV prevalence studies among drug users in four other cities (only 1 to 2 hours' drive from Amsterdam), showed that the prevalence of HIV among drug users outside Amsterdam is still low (less than 4%).

Copyright 1994 by the National Academy of Sciences. All rights reserved.
Bookshelf ID: NBK236662

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