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Volunteer bias in nonrandomized evaluations of the efficacy of needle-exchange programs

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Abstract

Objective

Nonrandomized comparisons of the incidence of HIV and hepatitis B and C between injection drug users (IDUs) who do and do not attend voluntary needle-exchange programs may be subject to bias. To explore possible sources of bias, we examined characteristics associated with voluntarily beginning or ceasing to participate in the Seattle needle exchange.

Methods

In a cohort of 2,879 IDUs, a standardized questionnaire measured characteristics present at enrollment. We examined the relation of these characteristics to the proportion of IDUs who began to use the program during the ensuing 12-month follow-up period and to the proportion of current exchangers who dropped out during that period of time.

Results

Of the 494 never-exchangers at baseline, 32% attended the exchange program during follow-up; those who reported sharing syringes or who were homeless at enrollment were more likely to become new exchange users (adjusted risk ratio [ARR] for becoming an exchange user = 1.8 for those who shared syringes, and ARR=2.2, for those who were homeless). Of 1,274 current exchangers, 16% stopped using the exchange during follow-up, with daily injectors (ARR=0.6) and those who reported backloading (ARR=0.6) being relatively less likely to drop out of the exchange.

Conclusions

The analysis suggests that IDUs participating in needle-exchange programs at a given point in time may include a particularly high proportion of those injectors whose pattern of drug use puts them at elevated risk of blood-borne viral infections.

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References

  1. Buning EC. Effect of Amsterdam needle and syringe exchange.Int J Addict. 1991;26: 1303–1311.

    CAS  PubMed  Google Scholar 

  2. Stimson GV. Syringe exchange programmes for injecting drug users.AIDS. 1989;3: 253–260.

    CAS  PubMed  Google Scholar 

  3. Hagan H, Des Jarlais DC, Purchase D et al. An interview study of participants in the Tacoma, Washington syringe exchange.Addiction. 1993;88:1691–1697.

    Article  CAS  PubMed  Google Scholar 

  4. Hartgers C, van Ameijden EJC, van den Hoek JAR, Coutinho RA. Needle sharing and participation in the Amsterdam syringe exchange program among HIV-seronegative injecting drug users.Public Health Rep. 1992;107:675–681.

    CAS  PubMed  Google Scholar 

  5. Hahn JA, Vranizan KM, Moss AR. Who uses needle exchange? A study of injection drug users in treatment in San Francisco, 1989–1990.J Acquir Immune Defic Syndr Hum Retrovirol. 1997;18:157–164.

    Google Scholar 

  6. van Ameijden EJC, van den Hoek JAR, van Haastrecht HJA, Coutinho RA. The harm reduction approach and risk factors for human immunodeficiency virus (HIV) seroconversion in injecting drug users, Amsterdam.Am J Epidemiol. 1992;136:236–243.

    PubMed  Google Scholar 

  7. Strathdee S, Patrick DM, Currie SL et al. Needle exchange is not enough: lessons from the Vancouver injecting drug use study.AIDS. 1997;11:F59-F65.

    Article  CAS  PubMed  Google Scholar 

  8. Bruneau J, Lamothe F, Franco E et al. High rates of HIV infection among injection drug users participating in needle exchange programs in Montreal: results of a cohort study.Am J Epidemiol. 1997;146:994–1002.

    CAS  PubMed  Google Scholar 

  9. Vlahov D, Junge B, Brookmeyer R et al. Reductions in high-risk drug use behaviors among participants in the Baltimore needle exchange program.J Acquir Immune Defic Syndr Hum Retrovirol. 1997;16:400–406.

    CAS  PubMed  Google Scholar 

  10. Hagan H, Des Jarlais DC, Friedman SR et al. Reduced risk of hepatitis B and hepatitis C among injection drug users in the Tacoma syringe exchange program.Am J Public Health. 1995;85:1531–1537.

    CAS  PubMed  Google Scholar 

  11. Des Jarlais DC, Marmor M, Paone D et al. HIV incidence among injecting drug users in New York City syringe-exchange programs.Lancet. 1996;348:987–991.

    Article  PubMed  Google Scholar 

  12. Hagan H, McGough JP, Thiede H et al. Syringe exchange and risk of infection with hepatitis B and C viruses.Am J Epidemiol. 1999;149:203–213.

    CAS  PubMed  Google Scholar 

  13. Morrison A.Screening in Chronic Disease. Oxford, England: Oxford University Press; 1991.

    Google Scholar 

  14. Greenland S. The effect of misclassification in the presence of covariates.Am J Epidemiol. 1980;112:564–569.

    CAS  PubMed  Google Scholar 

  15. Armstrong BK, White E, Saracci R.Principles of Exposure Measurement. Oxford, England: Oxford Medical Publications; 1992.

    Google Scholar 

  16. Schecter MT, Strathdee SA, Cornelisse PGA et al. Do needle exchange programmes increase the spread of HIV among injection drug users? An investigation of the Vancouver outbreak.AIDS. 1999;13:F45-F51.

    Google Scholar 

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Correspondence to Holly Hagan MPH, PhD.

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Hagan, H., McGough, J.P., Thiede, H. et al. Volunteer bias in nonrandomized evaluations of the efficacy of needle-exchange programs. J Urban Health 77, 103–112 (2000). https://doi.org/10.1007/BF02350966

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