Appendix D
Tables Summarizing the Evidence on Multi-Component HIV Prevention Programs That Include Needle and Syringe Exchange (NSE)



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Appendix D Tables Summarizing the Evidence on Multi-Component HIV Prevention Programs That Include Needle and Syringe Exchange (NSE)

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TABLE D-1 Case-Control Studies Study Description Sample Size (n) *Hagan et al., 1995 Examines the association between use of syringe exchange and hepatitis B and C in IDUs. Cases: 28 IDUs with acute hepatitis B; 20 IDUs with acute hepatitis C. Controls: IDUs with no markers of exposure to hepatitis B or C (n=38 and 26, respectively). *Patrick et al., 1997 Identifies determinants of HIV seroconversion among IDUs during a period of rising prevalence in Vancouver despite the prevalence of NSE and outreach. Cases: IDUs with a new positive HIV test after January 1, 1994, and a negative test within the prior 18 months (n=89). Controls: required 2 negative tests during the same period (n=192).

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Outcome Measures Results Limitations Syringe exchange use; hepatitis B and C infection. 75% of case patients with hepatitis B and 26% of control subjects had never used the exchange; similar proportions were found for the hepatitis C case and control groups. After adjustment for demographic characteristics and duration of drug use, nonuse of the exchange was associated with a six-fold greater risk of hepatitis B (OR=5.5; 95% CI: 1.5–20.4) and a sevenfold greater risk of hepatitis C (OR=7.3; 95%CI: 1.6–32.8). Source population were IDUs in Pierce County (Washington) and were at risk for developing hepatitis B or C. May have been differences between the injection practices of cases and controls which may have resulted in uncontrolled confounding. Cases and controls may have differed in their use of other strategies (bleach, syringe purchase in pharmacies, etc.) to prevent infection. The Tacoma syringe exchange’s role as the primary source of HIV prevention for local IDUs may have contributed to the magnitude of the association between syringe exchange and risk of viral hepatitis. Determinants of HIV seroconversion. Multivariate analysis showed borrowing syringes, unstable housing, and injecting ≥ 4 times daily to be independently associated with seroconversion. Protective associations were found between sex with opposite gender and tetrahydrocannabinol use. Cases may have had differential recall of events than controls. Self-reported data. Study focused on incident cases of HIV and systematically excluded populations in which HIV is already highly prevalent. Statistical power was limited with respect to ability to do subgroup analyses.

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Study Description Sample Size (n) van Ameijden et al., 1992 Assesses risk factors for HIV seroconversion among IDU and investigates if HIV prevention services in Amsterdam have a protective effect on HIV seroconversion. Cases: 31 IDU seroconverters Controls: 202 seronegative IDUs *Indicates an article selected by the Committee for relevance or sound study design.

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Outcome Measures Results Limitations HIV seroconversion No evidence was found that receiving daily methadone treatments at methadone posts and obtaining new needles/ syringes via the NSE were protective. Three independent risk factors for seroconversion were found in logistic regression: living >10 years in Amsterdam (OR=2.45; 95% CI: 1.09–5.53); first injection less than/equal to 2 years ago (OR=3.43; 95% CI: 1.20–9.81); and injecting mainly at home (OR=0.39; 95% CI: 0.18–0.88). Self-reported data. Small statistical power and the need to dichotomize most variables because of the small number of seroconverters. Only persons who visited two times or more were included, and these persons may be different from those who visited only once or those who never visited.

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TABLE D-2 Prospective Cohort Studies Study Description Sample Size (n) *Bluthenthal et al., 2000 Determines whether use of syringe exchange is associated with cessation of syringe sharing among high-risk injecting drug users. 340 high-risk injection drug users. *Bruneau et al., 1997 Assesses the association between risk behavior and HIV seroprevalence and seroincidence among IDUs in Montreal. The association was examined in three risk assessment scenarios using intensive covariate adjustment for confounders: a cross-sectional analysis of NSE use at entry as a determinant of seroprevalence; a cohort analysis of NSE use at entry as a predictor of subsequent seroconversion; and a nested case-control analysis of NSE participation during follow-up as a predictor of seroconversion. 974 HIV-negative IDUs.

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Outcome Measures Results Limitations Syringe sharing; use of syringe exchange. At follow-up interview, 60% reported quitting syringe sharing. IDUs who began using the syringe exchange were more likely to quit sharing syringes (AOR=2.68; 95% CI: 1.35–5.33), as were those who continued using the syringe exchange program (AOR=1.98; 95% CI: 1.05–3.75). Participants not randomly selected. Biases associated with self-reported data regarding sensitive and stigmatized behavior. Comparison group was made up of IDUs at high risk who reside in a community with syringe access limited to NSE. HIV seroprevalence and seroincidence. In the cohort study, there were 89 incident cases of HIV infection, with a cumulative probability of HIV seroconversion of 33% for NSE users and 13% for nonusers (p<0.0001). In the nested case-control study, consistent NSE use was associated with HIV seroconversion during follow-up (OR=10.5; 95% CI: 2.7-41.0). Study is observational and was not specifically designed to evaluate the efficacy of NSE in preventing HIV infection. Findings not generalizable because of the type of recruitment and the differences between participants and those lost to follow-up. Possible misclassification bias.

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Study Description Sample Size (n) *Bruneau et al., 2004 Identifies factors associated with sustained cessation of injection, and examines the relationship between sustained cessation and prior injection frequency between 1995 and 1999 in Montreal. 1,004 IDUs. Cox et al., 2000 Presents findings of an Irish follow-up study to establish the effectiveness of syringe exchanges as a strategy to prevent HIV in IDUs. 370 IDUs who attended the Merchants Quay Projects Health Promotion Unit, between May 1997 and October 1998.

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Outcome Measures Results Limitations Sustained injection cessation. 18.5% of IDUs reported a period of sustained injection cessation during the study period. Attending NSEs or pharmacies appeared to be a modifier of the relation between cessation and prior injection frequency. (OR=0.68; 95% CI: 0.42–1.12) for IDUs who injected 30–100 times in the month prior to interview and attended NSEs or pharmacies. (OR=0.07; 95% CI: 0.01–0.30) for IDUs who did not use these services. Majority of study participants were cocaine addicts. Self-reported data. Possible misclassification bias of outcome and exposure. Source population was dependent upon self-selection. Frequency of injection; needle sharing; condom use. Significant reduction in the frequency of injection; evidence of positive behavior change in relation to improved injection practices. No substantial change in respondents’ self-reported sharing of injecting paraphernalia or condom use. Self-reported data. Possible selection bias.

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Study Description Sample Size (n) Des Jarlais et al., 1996 Uses meta-analytic techniques to combine HIV incidence data from three studies: the Syringe Exchange Evaluation, the Vaccine Preparedness Initiative, and the National AIDS Demonstration Research program (NADR). Syringe Exchange Evaluation study, n=280; Vaccine Preparedness Initiative cohort, n=133 continuing exchangers and n=188 non-exchangers; and the NADR, n=1029. Donoghoe et al., 1989 Uses a questionnaire to measure changes in sexual behavior among syringe exchange clients over 2–4 months. 142 NSE clients.

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Outcome Measures Results Limitations HIV incidence. HIV incidence among continuing exchange users in the Syringe Exchange Evaluation was 1.58 per 100 person-years at risk (95% CI: 0.54–4.65). Among continuing NSE users in the Vaccine Preparedness Initiative HIV incidence was 1.38 per 100 person-years at risk (95% CI: 0.23–4.57). Incidence among non-users of the exchange in the Vaccine Preparedness Initiative was 5.26 per 100 person-years at risk (95% CI: 2.41, 11.49). In the NADR cities it was 6.23 per 100 person-years at risk (95% CI:4.4, 8.6). Not using an NSE was associated with a hazard ratio of 3.35 (1.29, 8.65) for incidence of HIV infection, compared with using an NSE, in a multivariate proportional hazards analysis. Important local conditions that created a strong contrast in the risk for HIV infection between syringe-exchange participants and non-participants. No causal link between participation in an NSE and lower HIV incidence can be established. Number of sexual partners; condom use. Number of participants having no sexual partners increased from 23% to 31%; number having multiple partners decreased from 26% to 21%; and the number having regular partners increased slightly from 49% to 52%. Overall, 79% reported not using condoms. Self-reported data. Reported changes were not significant.

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TABLE D-4 Selected Serial Cross-Sectional Studies Study Description Sample Size (n) Des Jarlais et al., 2005b Estimates HIV incidence among IDUs in NYC from 1990 to 2002 to assess the impact of an expansion of syringe exchange services, using the Serologic Testing Algorithm for Recent HIV Seroconversion (STARHS) system. 3,651 IDUs. Hammett et al., 2006 Evaluation of an intervention (peer education and provision of clean needles through distribution and pharmacy vouchers) in the cross-border region of China and Vietnam. Surveys conducted prior to the start of the intervention and at 6, 12, 18, and 24 months thereafter. Van Ameijden et al., 1994 Studies trends in injecting risk behavior from 1986 to 1992 in Amsterdam. 616 IDUs.

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Outcome Measures Results Limitations HIV incidence. HIV incidence declined from 3.55/100 person-years at risk (PYAR) from 1990 to 1992 to 2.63/100 PYAR from 1993 to 1995, to 1.05/100 PYAR from 1996 to 1998, and to 0.77/100 PYAR from 1999 to 2002 (p<0.001). There was a strong linear relationship between the annual numbers of syringes exchanged and estimated HIV incidence. Limitations of STARHS include: Need larger sample size to accurately calculate incidence using STARHS. Potential for false negative HIV results because EIA is less sensitive and may fail to detect antibodies in some cases. Program coverage of IDUs; IDUs’ risk behaviors; HIV prevalence among IDUs during the first 24 months after the intervention was initiated. Drug-related risk behaviors declined in frequency, and HIV prevalence among IDUs remained stable in China and declined in Vietnam, over the 24 months since the intervention. Based on non-random samples of IDUs. Self-reported data. Absence of control groups. Borrowing and lending of injection equipment; reuse of needles and syringes. Borrowing of injection equipment declined from 51% to 20%; lending of injection equipment declined from 46% to 10%; and reuse of needles and syringes declined from 63% to 39%. Indications were found that voluntary HIV testing led to less borrowing, lending, and reuse of equipment; and obtaining needles via NSE led to less reuse of needles/syringes. Participants showing a high level of risk may have been selectively recruited earlier in time. Selected only drug users who had injected in the preceding 6 months. Self-reported data. Outcomes of borrowing and lending are only roughly measured.

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Study Description Sample Size (n) Watters et al., 1994 Evaluates an all-volunteer syringe exchange program in San Francisco using 11 semiannual cross-sectional surveys between December 1986 and June 1992. 5,644 IDUs recruited in two 21-day drug detoxification clinics and three street settings.

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Outcome Measures Results Limitations Use of syringe exchange program; source of syringes; frequency of injection; initiation into drug injection; frequency of syringe sharing. In 1992, 45% reported usually obtaining injection equipment from the syringe exchange, and 61% reported using the program within the past year. From December 1986 to June 1992, the median reported frequency of injection declined from 1.9 injections per day to 0.7 injections per day, and the percentage of new initiates into injection drug use decreased from 3% to 1%. Self-reported data. Identifies correlates of sharing syringes, but not causes of reduced sharing. Targeted samples used were not true random samples.

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TABLE D-5 Selected Cross-Sectional Studies Study Description Sample Size (n) Hagan et al., 1993 Reports on the operation and effectiveness of the first legally operated syringe exchange program in the U.S. in Tacoma, Washington. 204 syringe exchange users. Keene et al., 1993 Two-year study evaluates specialist- and community-based NSE in Wales from 1990–1991. 152 NSE attenders; 176 non-attenders. Kerr et al., 2005 Examines factors associated with syringe sharing in a community-recruited cohort of illicit IDUs in a setting where a safer injection facility recently opened. 431 active IDUs. Klee et al., 1991 Compares three groups of IDUs (on methadone treatment for more than 6 months, on methadone for less than 6 months, no methadone treatment) based on variables believed to be associated with sharing of injecting equipment. 98 IDUs receiving no treatment; 74 IDUs receiving methadone for > 6 months; 44 IDUs receiving methadone for < 6 months.

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Outcome Measures Results Limitations Drug use; injection practices; unsafe injections. Frequency of injection did not change, but the frequency of unsafe injection declined (from 56 to 30 times a month). There was no increase in illicit drug use. Retrospective sampling. Self-reported data. 28% of potential subjects refused to participate because of the need to relieve withdrawal symptoms. Syringe sharing in the last year and the last 4 months. Only 9% of attenders had recently shared syringes in 1990 (10% in 1991) compared with 41% of non-attenders (39% in 1991). 80% of needles and syringes were returned. Self reported data. Comparison of two cross-sectional surveys. Syringe sharing (borrowing or lending of a used syringe in the past 6 months). Among participating IDUs, 11.4% reported sharing syringes. In logistic regression analyses, use of the safer injection facility was independently associated with reduced syringe sharing (AOR=0.30; 95% CI: 0.11–0.82; p=0.02), after adjustment for relevant sociodemographic and drug-use characteristics. Findings could be due to residual confounding if the SIF had selected IDUs who were inherently at lower risk of syringe sharing. Not a random sample. Cannot establish causal relationship because of study design. Self reported data. Sharing of injecting equipment; use of NSE. Regular use of needle exchange was associated with the passing on of used equipment to others. Self-reported data. Sample may not be representative of the population (methadone program clients). Statistical analysis did not clarify the effect of NSE.

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Study Description Sample Size (n) Longshore et al., 2001 Tests frequency of attendance at an NSE in Providence, Rhode Island, as a correlate of injection risk indicators. 248 IDUs. Vazirian et al., 2005 Compares the risk behaviors of IDUs with differential exposure rates to an HIV outreach program in Tehran, Iran. The outreach program includes a needle and syringe exchange program. 213 IDUs and 85 non-IDUs.

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Outcome Measures Results Limitations Sharing of needles, cookers, and cotton filters; cleaning of the skin before injecting; and use of bleach as a needle disinfectant. Results showed that IDUs who attended the NSE less frequently were more likely to report needle sharing, less likely to report always cleaning their skin, and more likely to report sharing cookers (the NSE distributes cotton and cookers in addition to needles). There was no association between NSE attendance and using bleach as a disinfectant. May have underestimated relevance of NSE attendance for skin cleaning. Self-reported data. Frequency of NSE attendance is not a sensitive measure. IDUs were not randomly assigned to the NSE or a non-NSE control group, and NSE attendees were not randomly assigned to various frequencies of attendance. Contact with outreach program; length of contact; number of syringes received; HIV risk characteristics. Of those (37) who received few needles/syringes from the program, 18.9% reported using a shared needle or syringe at last injection. None of the 68 IDUs who received >7 syringes per week from the program shared a needle at last injection. There was no difference in the two groups in sharing of cookers, condom use during last sex, level of HIV knowledge, or history of HIV testing. Study design does not allow authors to make causal associations. Selection bias due to convenience sampling. Self reported data.

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