Identifying heterogeneity among injection drug users: a cluster analysis approach.

OBJECTIVES We used cluster analysis to subdivide a population of injection drug users and identify previously unknown behavioral heterogeneity within that population. METHODS We applied cluster analysis techniques to data collected in a cross-sectional survey of injection drug users in Winnipeg, Manitoba. The clustering variables we used were based on receptive syringe sharing, ethnicity, and types of drugs injected. RESULTS Seven clusters were identified for both male and female injection drug users. Some relationships previously revealed in our study setting, such as the known relationship between Talwin (pentazocine) and Ritalin (methylphenidate) use, injection in hotels, and hepatitis C virus prevalence, were confirmed through our cluster analysis approach. Also, relationships between drug use and infection risk not previously observed in our study setting were identified, an example being a cluster of female crystal methamphetamine users who exhibited high-risk behaviors but an absence or low prevalence of blood-borne pathogens. CONCLUSIONS Cluster analysis was useful in both confirming relationships previously identified and identifying new ones relevant to public health research and interventions.

[1]  B. Edlin,et al.  The effect of syringe exchange use on high-risk injection drug users: a cohort study , 2000, AIDS.

[2]  J. Potterat,et al.  Sexual networks and sexually transmitted infections: A tale of two cities , 2001, Journal of Urban Health.

[3]  D. Huo,et al.  HIV Risk Practices Among Needle Exchange Users and Nonusers in Chicago , 2004, Journal of acquired immune deficiency syndromes.

[4]  S. Bierma-Zeinstra,et al.  Hip problems in older adults: classification by cluster analysis. , 2001, Journal of clinical epidemiology.

[5]  C. Latkin,et al.  Micro-social structural approaches to HIV prevention: a social ecological perspective , 2005, AIDS care.

[6]  Roger K. Blashfield,et al.  Mixture model tests of cluster analysis: Accuracy of four agglomerative hierarchical methods. , 1976 .

[7]  V. Hesselbrock,et al.  Types of alcoholics, I. Evidence for an empirically derived typology based on indicators of vulnerability and severity. , 1992, Archives of general psychiatry.

[8]  A. Gielen,et al.  SOCIAL FACTORS RELATED TO SYRINGE SHARING AMONG INJECTING PARTNERS: A FOCUS ON GENDER , 2001, Substance use & misuse.

[9]  R. Hogg,et al.  Factors associated with persistent high-risk syringe sharing in the presence of an established needle exchange programme. , 2002, AIDS.

[10]  M. Schechter,et al.  Determinants of HIV seroconversion in drug users during a period of rising prevalence in Vancouver , 1997 .

[11]  T. S. Jones,et al.  HIV risk behaviors associated with the injection process: multiperson use of drug injection equipment and paraphernalia in injection drug user networks. , 1998, Substance use & misuse.

[12]  Julio S. G. Montaner,et al.  Needle exchange is not enough: lessons from the Vancouver injecting drug use study , 1997, AIDS.

[13]  T. Laveist.  On the Study of Race, Racism, and Health: A Shift from Description to Explanation , 2000, International journal of health services : planning, administration, evaluation.

[14]  J. Barry,et al.  Syringe borrowing persists in Dublin despite harm reduction interventions. , 2001, Addiction.

[15]  D. Fisher.  High‐Risk Sexual Behavior Among Drug Users: The Utility of a Typology of Alcohol Variables , 1998, Sexually transmitted diseases.

[16]  M. Schechter,et al.  Factors associated with frequent needle exchange program attendance in injection drug users in Vancouver, Canada. , 1998, Journal of acquired immune deficiency syndromes and human retrovirology : official publication of the International Retrovirology Association.

[17]  A. Baron,et al.  Drug Sharing Among Heroin Networks: Implications for HIV and Hepatitis B and C Prevention , 2005, AIDS and Behavior.

[18]  M. Hesselbrock,et al.  Are there empirically supported and clinically useful subtypes of alcohol dependence? , 2006, Addiction.

[19]  M. Schechter,et al.  The impact of needle-exchange programs on the spread of HIV among injection drug users: A simulation study , 2003, Journal of Urban Health.

[20]  A. Lovell,et al.  Risking risk: the influence of types of capital and social networks on the injection practices of drug users. , 2002, Social science & medicine.

[21]  Ali S. Hadi,et al.  Finding Groups in Data: An Introduction to Chster Analysis , 1991 .

[22]  Douglas A Luke,et al.  Getting the Big Picture in Community Science: Methods That Capture Context , 2005, American journal of community psychology.

[23]  R. Macrae,et al.  Gendered power dynamics and HIV risk in drug-using sexual relationships , 2000, AIDS care.

[24]  W. Schlenger,et al.  "Islands of Risk": subgroups of adolescents at risk for HIV. , 2006, Journal of pediatric psychology.

[25]  R. Rothenberg,et al.  Sociometric risk networks and risk for HIV infection. , 1997, American journal of public health.

[26]  K. Zapert,et al.  Patterns of Substance Use in Early Through Late Adolescence , 2002, American journal of community psychology.

[27]  M. Barnard.  Needle sharing in context: patterns of sharing among men and women injectors and HIV risks. , 1993, Addiction.

[28]  Julio S. G. Montaner,et al.  Attendance, drug use patterns, and referrals made from North America's first supervised injection facility. , 2006, Drug and alcohol dependence.

[29]  D. Vlahov,et al.  Correlates of needle sharing among injection drug users. , 1994, American journal of public health.

[30]  M. Mattson,et al.  Research on matching alcoholic patients to treatments: findings, issues, and implications. , 1992, Journal of addictive diseases.

[31]  E. Laumann,et al.  Racial/ethnic group differences in the prevalence of sexually transmitted diseases in the United States: a network explanation. , 1999, Sexually transmitted diseases.

[32]  D. Celentano,et al.  The social epidemiology of human immunodeficiency virus/acquired immunodeficiency syndrome. , 2004, Epidemiologic reviews.

[33]  B. Everitt,et al.  A Monte Carlo Study of the Recovery of Cluster Structure in Binary Data by Hierarchical Clustering Techniques. , 1987, Multivariate behavioral research.

[34]  M Marmot,et al.  Dietary patterns among a national random sample of British adults , 2001, Journal of epidemiology and community health.

[35]  J. Marrazzo,et al.  Within the Hidden Epidemic: Sexually Transmitted Diseases and HIV/AIDS Among American Indians and Alaska Natives , 2007, Sexually transmitted diseases.

[36]  D. Vlahov,et al.  Selective risk taking among needle exchange participants: implications for supplemental interventions. , 2001, American journal of public health.

[37]  C P Friedman,et al.  Issues and challenges in the design of curriculum information systems. , 1995, Academic medicine : journal of the Association of American Medical Colleges.

[38]  Mohammed Rehan Malik,et al.  Sterile syringe access conditions and variations in HIV risk among drug injectors in three cities. , 2004, Addiction.

[39]  T. Rhodes,et al.  The social structural production of HIV risk among injecting drug users. , 2005, Social science & medicine.

[40]  J. H. Ward.  Hierarchical Grouping to Optimize an Objective Function , 1963 .

[41]  P. Sneath,et al.  Some thoughts on bacterial classification. , 1957, Journal of general microbiology.

[42]  J. Zubin.  A technique for measuring like-mindedness. , 1938 .

[43]  L C Morey,et al.  Empirical classifications of alcoholism: a review. , 1981, Journal of studies on alcohol.

[44]  M. Schechter,et al.  Risk factors for elevated HIV incidence rates among female injection drug users in Vancouver. , 2002, CMAJ : Canadian Medical Association journal = journal de l'Association medicale canadienne.

[45]  J. Montaner,et al.  Frequent needle exchange use and HIV incidence in Vancouver, Canada. , 2007, The American journal of medicine.

[46]  D. Vlahov,et al.  The role of needle exchange programs in HIV prevention. , 1998, Public health reports.

[47]  Richard O. Duda,et al.  Pattern classification and scene analysis , 1974, A Wiley-Interscience publication.

[48]  J. Beitchman,et al.  COMORBIDITY OF PSYCHIATRIC AND SUBSTANCE USE DISORDERS IN LATE ADOLESCENCE: A CLUSTER ANALYTIC APPROACH , 2001, The American journal of drug and alcohol abuse.

[49]  Yoshimi Fukuoka,et al.  Cluster analysis: a useful technique to identify elderly cardiac patients at risk for poor quality of life , 2007, Quality of Life Research.

[50]  N. Anderson.  Integrating behavioral and social sciences research at the National Institutes of Health, U.S.A. , 1997, Social science & medicine.

[51]  S. Kunitz,et al.  Types Of Alcoholics , 2000 .

[52]  M. Busch,et al.  Hepatitis C virus seroconversion among young injection drug users: relationships and risks. , 2002, The Journal of infectious diseases.

[53]  D. Huo,et al.  Drug use and HIV risk practices of secondary and primary needle exchange users. , 2005, AIDS Education and Prevention.

[54]  R. Brunham.  Core group theory: a central concept in STD epidemiology , 1997 .

[55]  J. Montaner,et al.  Increasing use and associated harms of crystal methamphetamine injection in a Canadian setting. , 2007, Drug and alcohol dependence.

[56]  J. Desenclos,et al.  Harm reduction interventions, behaviours and associated health outcomes in France, 1996-2003. , 2005, Addiction.

[57]  William C Miller,et al.  Sexual and drug behavior patterns and HIV and STD racial disparities: the need for new directions. , 2007, American journal of public health.

[58]  J. Wylie,et al.  Patterns of Chlamydia and Gonorrhea Infection in Sexual Networks in Manitoba, Canada , 2001, Sexually transmitted diseases.

[59]  B. Edlin,et al.  Risk factors among IDUs who give injections to or receive injections from other drug users. , 1999, Addiction.

[60]  Jeffrey R. Taylor,et al.  Exploratory cluster analysis of behavioral risks for chronic disease and injury: Implications for tailoring health promotion services , 1990, Journal of Community Health.

[61]  L. Fisher,et al.  391: A Monte Carlo Comparison of Six Clustering Procedures , 1975 .

[62]  Lena Shah,et al.  Demographic, risk behaviour and personal network variables associated with prevalent hepatitis C, hepatitis B, and HIV infection in injection drug users in Winnipeg, Canada , 2006, BMC public health.

[63]  J. D. Linden,et al.  Multivariate classification of alcoholics by means of the MMPI. , 1969, Journal of abnormal psychology.

[64]  A. Söderlund,et al.  Classification of patients with whiplash associated disorders (WAD): Reliable and valid subgroups based on the Multidimensional Pain Inventory (MPI‐S) , 2006, European journal of pain.

[65]  M. Schechter,et al.  Do needle exchange programmes increase the spread of HIV among injection drug users?: an investigation of the Vancouver outbreak. , 1999, AIDS.

[66]  Patrick Peretti-Watel,et al.  Drug use patterns and adherence to treatment among HIV-positive patients: evidence from a large sample of French outpatients (ANRS-EN12-VESPA 2003). , 2006, Drug and alcohol dependence.

[67]  T. Manolio,et al.  Cluster analysis and patterns of findings on cranial magnetic resonance imaging of the elderly: the Cardiovascular Health Study. , 2001, Archives of neurology.

[68]  J. Boivin,et al.  Characterizing the Drug-injecting Networks of Cocaine and Heroin Injectors in Montreal , 2006, Canadian journal of public health = Revue canadienne de sante publique.

[69]  J. Boivin,et al.  HIV risk profile of male street youth involved in survival sex , 2004, Sexually Transmitted Infections.

[70]  S. Aral,et al.  Behavioral aspects of sexually transmitted diseases: core groups and bridge populations. , 2000, Sexually transmitted diseases.

[71]  M. Schechter,et al.  Social determinants predict needle-sharing behaviour among injection drug users in Vancouver, Canada. , 1997, Addiction.

[72]  R. Abeles,et al.  Social science and health research: growth at the National Institutes of Health. , 2004, American journal of public health.

[73]  R. Curtis,et al.  Syringe-mediated drug sharing among injecting drug users: patterns, social context and implications for transmission of blood-borne pathogens. , 1996, Social science & medicine.

[74]  Predictors of Sharing Drugs Among Injection Drug Users in the South Bronx: Implications for HIV Transmission , 2003, Journal of psychoactive drugs.

[75]  N. Read,et al.  Cluster analysis of symptoms and health seeking behaviour differentiates subgroups of patients with severe irritable bowel syndrome , 2003, Gut.

[76]  M. Tyndall,et al.  The impact of unregulated single room occupancy hotels on the health status of illicit drug users in Vancouver , 2006 .

[77]  A. Moss,et al.  Hepatitis C virus infection and needle exchange use among young injection drug users in San Francisco , 2001, Hepatology.

[78]  J E Overall,et al.  Population recovery capabilities of 35 cluster analysis methods. , 1993, Journal of clinical psychology.

[79]  F. Lert,et al.  Unsafe injecting practices among attendees of syringe exchange programmes in France. , 2001, Addiction.

[80]  M. Handcock,et al.  Bridge populations in the spread of HIV/AIDS in Thailand. , 1996, AIDS.

[81]  Robert R. Sokal,et al.  A statistical method for evaluating systematic relationships , 1958 .

[82]  L. R. Dice.  Measures of the Amount of Ecologic Association Between Species , 1945 .

[83]  T. Furmark,et al.  Social phobia subtypes in the general population revealed by cluster analysis , 2000, Psychological Medicine.

[84]  B. Smyth,et al.  Recipient syringe sharing and its relationship to social proximity, perception of risk and preparedness to share. , 2007, Addictive behaviors.

[85]  Lena Shah,et al.  Incorporating geographic settings into a social network analysis of injection drug use and bloodborne pathogen prevalence. , 2007, Health & place.

[86]  C. Robert Cloninger,et al.  Inheritance of alcohol abuse. Cross-fostering analysis of adopted men. , 1981, Archives of general psychiatry.

[87]  Brian Everitt,et al.  Cluster analysis , 1974 .

[88]  T. Caliński,et al.  A dendrite method for cluster analysis , 1974 .

[89]  J. Frankish,et al.  The Future Face of Coinfection: Prevalence and Incidence of HIV and Hepatitis C Virus Coinfection Among Young Injection Drug Users , 2004, Journal of acquired immune deficiency syndromes.

[90]  Peter M. Bentler,et al.  Impact of Marriage on HIV/AIDS Risk Behaviors Among Impoverished, At-Risk Couples: A Multilevel Latent Variable Approach , 2005, AIDS and Behavior.

[91]  Peter Vickerman,et al.  Model Projections on the Required Coverage of Syringe Distribution to Prevent HIV Epidemics Among Injecting Drug Users , 2006, Journal of acquired immune deficiency syndromes.

[92]  C. Boustière,et al.  Epidemiological changes in hepatitis C virus genotypes in France: evidence in intravenous drug users , 2002, Journal of viral hepatitis.

[93]  M. Schechter,et al.  Intensive injection cocaine use as the primary risk factor in the Vancouver HIV-1 epidemic , 2003, AIDS.

[94]  J. Wylie,et al.  Determinants of injection drug user (IDU) syringe sharing: the relationship between availability of syringes and risk network member characteristics in Winnipeg, Canada. , 2007, Addiction.

[95]  K. Holmes,et al.  Sexual mixing patterns in the spread of gonococcal and chlamydial infections. , 1999, American journal of public health.

[96]  J. Wasserheit,et al.  The dynamic topology of sexually transmitted disease epidemics: implications for prevention strategies. , 1996, The Journal of infectious diseases.

[97]  R. Curtis,et al.  The relevance of drug injectors' social and risk networks for understanding and preventing HIV infection. , 1994, Social science & medicine.

[98]  M. Aldenderfer.  Cluster Analysis , 1984 .

[99]  J. Montaner,et al.  Unsafe injection practices in a cohort of injection drug users in Vancouver: could safer injecting rooms help? , 2001, CMAJ : Canadian Medical Association journal = journal de l'Association medicale canadienne.

[100]  Ball State,et al.  Comparison of Distance Measures in Cluster Analysis with Dichotomous Data , 2004 .

[101]  R C Spear,et al.  Hierarchical cluster analysis applied to workers' exposures in fiberglass insulation manufacturing. , 1999, The Annals of occupational hygiene.

[102]  M. Schechter,et al.  Determinants of HIV seroconversion in injection drug users during a period of rising prevalence in Vancouver. , 1997, International journal of STD & AIDS.