Estimating the Size of an Injecting Drug User Population

Author(s)
Yang Zhao

Abstract

This article describes a sampling and estimation scheme for estimating the size of an injecting drug user (IDU) population by combining classical sampling and respondent-driven sampling procedures. It is designed to use the information from harm reduction programs, especially, Needle Exchange Programs (NEPs). The approach involves using respondent-driven sampling design to collect a sample of injecting drug users who appear at site of NEP in a certain period of time and to obtain retrospective self-report data on the number of friends among the IDUs and number of needles exchanged for each sampled injecting drug user. A methodology is developed to estimate the size of injecting drug users who have ever used the NEP during the fixed period of time, and which allows us to estimate the proportion of injecting drug users in using NEP. The size of the IDU population is estimated by dividing the total number of IDUs who using NEPs during the period of time by the estimated proportion of IDUs in the group. The technique holds promise for providing data needed to answer questions such as “What is the size of an IDU population in a city?” and “Is that size changing?” and better understand the dynamics of the IDU population. The methodology described here can also be used to estimate size of other hard-to-reach population by using information from harm reduction programs.

This article describes a sampling and estimation scheme for estimating the size of an injecting drug user (IDU) population by combining classical sampling and respondent-driven sampling procedures. It is designed to use the information from harm reduction programs, especially, Needle Exchange Programs (NEPs). The approach involves using respondent-driven sampling design to collect a sample of injecting drug users who appear at site of NEP in a certain period of time and to obtain retrospective self-report data on the number of friends among the IDUs and number of needles exchanged for each sampled injecting drug user. A methodology is developed to estimate the size of injecting drug users who have ever used the NEP during the fixed period of time, and which allows us to estimate the proportion of injecting drug users in using NEP. The size of the IDU population is estimated by dividing the total number of IDUs who using NEPs during the period of time by the estimated proportion of IDUs in the group. The technique holds promise for providing data needed to answer questions such as “What is the size of an IDU population in a city?” and “Is that size changing?” and better understand the dynamics of the IDU population. The methodology described here can also be used to estimate size of other hard-to-reach population by using information from harm reduction programs.

Keywords

Injecting Drug Users, Needle Exchange Programs, Respondent-Driven Sampling, Estimating the Size of an IDU Population

Injecting Drug Users, Needle Exchange Programs, Respondent-Driven Sampling, Estimating the Size of an IDU Population

Cite this paper

nullY. Zhao, "Estimating the Size of an Injecting Drug User Population,"*World Journal of AIDS*, Vol. 1 No. 3, 2011, pp. 88-93. doi: 10.4236/wja.2011.13013.

nullY. Zhao, "Estimating the Size of an Injecting Drug User Population,"

References

[1] Joint United Nations Programme on HIV/AIDS (UNAIDS), “Global Report: UNAIDS Report on the Global AIDS Epidemic 2010,” Geneva, 2010.

[2] B. M. Mathers, L. Degenhardt, B. Phillips, L. Wiessing, M. Hickman, S. Strathdee, A. Wodak, et al., “Global Epidemiology of Injecting Drug Use and HIV among People who Inject Drugs: A Systematic Review,” Lancet, Vol. 372, No, 9651, 2008, pp. 1733-1745.
doi:10.1016/S0140-6736(08)61311-2

[3] Centers for Diseases Control (CDC), “HIV Prevention Strategic Plan through 2005,” USA, 2001.

[4] C. P. Archibald, G. C. Jayaraman, C. Major, D. M. Patrick, S. M. Houston and D. Sutherland, “Estimating the Size of Hand-to-Reach Population: A Novel Method Using HIV Testing Data Compared to Other Methods,” AIDS, Vol. 15, 2001, pp. s41-s48.
doi:10.1097/00002030-200104003-00006

[5] J. Weekes and K. Cumberland, “Needle Exchange Programs (NEPs) FAQs,” 2004.
http://www.ccsa.ca/2004%20CCSA%20Documents/ccsa-010055-2004.pdf.Accessed on 11 May 2011

[6] Canadian Centre on Substance Abuse, “Injection Drug Users Overview,” 2009, accessed on 11 May 2011.
http://www.ccsa.ca/Eng/Topics/Populations/IDU

[7] K. L. DEHNE, M. ADELEKAN, A. CHATTERJEE and G. WEILER, “The Need for a Global Understanding of Epidemiological Data to Inform Human Immunodeficiency Virus (HIV) Prevention among Injecting Drug Users,” Bulletin on Narcotics, Vol. LIV, No. 1-2, 2002, pp. 117- 130.

[8] R. Muga, K. Langohr, J. Tor, A. Sanvisens, I. Serra and C. R. Rey-Joly, “Survival of HIV-Infected Injection Drug Users (IDUs) in the Highly Active Antiretroviral Therapy Era, Relative to Sex- and Age-Specific Survival of HIV-Un- infected IDUs,” Clinical Infectious Diseases, Vol. 45, No. 3, 2007, pp.370-376. doi:10.1086/519385

[9] Committee on the Prevention of HIV Infection among Injecting Drug Users in High-Risk Countries, “Preventing HIV Infection among Injecting Drug Users in High Risk Countries: An Assessment of the Evidence,” The National Academies Press, Washington, D.C., 2006.

[10] D. D. Heckathorn, “Respondent-Driven Sampling: A new Approach to the Study of Hidden Populations,” Social Problems, Vol. 44, No. 2, 1997, pp. 174-199.
doi:10.1525/sp.1997.44.2.03x0221m

[11] S. Zhang, P. Yan and C. Archibald, “Estimating the Size of IDU Population Using Needle Exchange Programs,” Proceedings of Statistics Canada Symposium 2004 Innovative Methods for Surveying Difficult-to-Reach Popultions, Statistics Canada, Ottawa, 2004, pp. 1-10.

[12] D. D. Heckathorn, “Extensions of Respondent-Driven sampling: Analyzing Continuous Variables and Controlling for Differential Recruitment,” Sociological Methodology, Vol. 31, No. 1, 2007, pp. 151-207.
doi:10.1111/j.1467-9531.2007.00188.x

[13] K. J. Gile and M. S. Handcock, “Respondent-Driven sampling: An Assessment of Current Methodology,” Sociological Methodology, Vol. 40, No. 1, 2010, pp. 285-327.
doi:10.1111/j.1467-9531.2010.01223.x

[14] M. J. Salganik and D. D. Heckathorn, “Sampling and Estimation in hidden Populations Using Respondent- driven Sampling,” Sociological Methodology, Vol. 34, No. 1, 2004, pp. 193-239.
doi:10.1111/j.0081-1750.2004.00152.x

[15] Public Health Agency of Canada, “Harm Reduction and Injection Drug Use: An International Comparative Study of Contextual Factors Influencing the Development and Implementation of Relevant Policies and Program,” 2003, accessed on 18 March 2006.
http://www.phac-aspc.gc.ca/hepc/pubs/hridu-rmudi/index-eng.php

[16] C. Strike, L. Leonard, M. Millson, S. Anstice, N. Berkeley and E. Medd, “Ontario Needle Exchange Programs: Best Practice Recommendations,” Toronto: Ontario Needle Exchange Coordinating Committee, 2006.

[17] C. L. Miller, M. Tyndall, P. Spittal, K. Li, A. Palepu and M. T. Schechter, “Risk-Taking Behaviors among Injecting Drug Users Who Obtain Syringes from Pharmacies, Fixed Sites, and Mobile Van Needle Exchanges,” Journal of Urban Health, Vol. 79, No. 2, 2002, pp. 257-265.
doi:10.1093/jurban/79.2.257

[18] C. Sarndal, B. Swensson and J. Wretman, “Model Assisted Survey Sampling,” Series in Statistics, Springer, New York, 1992.

[19] W. G. Cochran, “Sampling Techniques,” 3rd Edition, Wiley, New York, 1977.

[20] D. C. DesJarlais, C. McKnight, K. Eigo and P. Friedmann, “2000 United States Syringe Exchange Program Survey,” The Baron Edmond de Rothschild Chemical Dependency Institute, New York, 2000.

[21] M. MacDonald, A. D. Wodak, R. Ali, N. Crofts, P. H. Cunningham, K. A. Dolan, M. Kelaher, W. M. Loxley, I. van Beek and J. M. Kaldor, “HIV Prevalence and Risk Behaviour in Needle Exchange Attenders: A National Study. The Collaboration of Australian Needle Exchanges,” The Medecal Journal of Australia, Vol. 166, No. 5, 1997, pp. 237-240.

[22] M. Peggy, T. Myers, L. Calzavara, E. Wallace, C. Major, and N. Degani, “Regional Variation in HIV Prevalence and Risk Behaviours in Ontario Injection Drug Users,” Canadian Journal of Public Health, Vol. 94, No. 6, 2003, pp. 431-435.

[23] K. Vijayan, “An Exact Sampling Scheme: Generalization of a Method of Hanurav,” Journal of the Royal Statistical Society, Vol. 30, No. 6, 1968, pp. 499-513.

[24] K. W. R. Brewer, “A model of systematic sampling with unequal probabilities,” Australian Journal of Statistics, Vol. 5, 1963, pp. 93-105.
doi:10.1111/j.1467-842X.1963.tb00288.x

[25] S. M. Roos, “Probability Models,” 6th Edition, Academic Press, London, 1997.

[26] E. L. Korn and B. I. Graubard, “Analysis of Health Surveys,” Wiley Series in Probability and Statistics Survey Methodology Section, John Wiley & Sons, New York, 1999. doi:10.1002/9781118032619

[27] M. E. Thompson, “Theory of Sample Surveys,” Chapman & Hall, London, 1997.

[28] S. L. Lohr, “Sampling: Design and Analysis,” Duxbury Press, New York, 1999.

[29] C. Sarndal, B. Swensson and J. Wretman, “Model Assisted Survey Sampling,” Series in Statistics, Springer, New York, 1992.