JAIDS Journal of Acquired Immune Deficiency Syndromes:
Epidemiology and Social Science
Predictors of Sharing Injection Equipment by HIV-Seropositive Injection Drug Users
Latkin, Carl A PhD*; Buchanan, Amy S MHS†; Metsch, Lisa R PhD‡; Knight, Kelly MEd§; Latka, Mary H PhD‖; Mizuno, Yuko PhD¶; Knowlton, Amy R ScD*; the Intervention for Seropositive Injectors-Research Evaluation Team
From the Departments of *Health, Behavior and Society; and †Mental Health, Johns Hopkins Bloomberg School of Public Health, Baltimore, MD; ‡Department of Epidemiology and Public Health, Leonard M. Miller School of Medicine, University of Miami, Miami, FL; §AIDS Research Institute, University of California, San Francisco, CA; ‖Aurum Institute for Health Research, Johannesburg, South Africa; and ¶Division of HIV/AIDS Prevention, National Center for HIV, STD, and TB Prevention, Centers for Disease Control and Prevention, Atlanta, GA.
Received for publication April 4, 2008; accepted August 13, 2008.
Supported by the Centers for Disease Control and Prevention and the Health Resources and Services Administration.
The findings and conclusions in this report are those of the authors and do not necessarily represent the views of the Centers for Disease Control and Prevention.
Correspondence to: Carl A. Latkin, PhD, Department of Health, Behavior and Society, Johns Hopkins Bloomberg School of Public Health, 624 North Broadway, Room 737, Baltimore, MD 21205 (e-mail: firstname.lastname@example.org).
Among HIV-positive injection drug users (IDUs), we examined baseline predictors of lending needles and syringes and sharing cookers, cotton, and rinse water in the prior 3 months at follow-up. Participants were enrolled in Intervention for Seropositive Injectors-Research and Evaluation, a secondary prevention intervention for sexually active HIV-positive IDUs in 4 US cities during 2001-2005. The analyses involved 357 participants who reported injecting drugs in the prior 6 months at either the 6- or 12-month follow-up visit. About half (49%) reported at least 1 sharing episode. In adjusted analyses, peer norms supporting safer injection practices and having primary HIV medical care visits in the prior 6 months were associated with reporting no sharing of injection equipment. Higher levels of psychological distress were associated with a greater likelihood of reporting drug paraphernalia sharing. These findings suggest that intervention approaches for reducing HIV-seropositive IDUs' transmission of blood-borne infections should include peer-focused interventions to alter norms of drug paraphernalia sharing and promoting primary HIV care and mental health services.
Injection drug use (IDU) continues to be a significant source of HIV transmission. Many countries report IDU as the primary mode of HIV transmission.1-3 In some countries, injection drug users (IDUs) have reported reductions in syringe sharing; however, many IDUs continue to share syringes despite high levels of HIV knowledge, and a higher proportion report sharing other types of injection equipment used in the drug preparation process, such as cookers, cotton, and rinse water.4,5 In addition to the health concern of transmitting HIV, a large proportion of injectors, especially HIV-positive IDUs, are coinfected with hepatitis C virus, which is readily transmitted through the sharing of injection equipment.6
Numerous studies have identified correlates of sharing injection equipment,7-12 including type and frequency of drug use, relationship to injection partners, composition of social networks, availability of clean injection equipment, homelessness, fear of police, and laws and policies governing syringe access. Yet few prospective studies have focused on sharing injection equipment among sexually active HIV-seropositive injectors. The present study examined equipment sharing among HIV-seropositive IDUs who were enrolled in the Intervention for Seropositive Injectors-Research and Evaluation (INSPIRE) study (2001-2005).13
A prior cross-sectional analysis of INSPIRE baseline data examined lending of syringes and needles to partners perceived to be HIV-seronegative or of unknown HIV serostatus.14 The multivariate analyses revealed that older IDUs, high school graduates, and those reporting more supportive peer norms for safer injection practices were less likely to report lending syringes. Admission to a hospital for drug treatment in the past 6 months, injecting with more than 1 person in the past 3 months, and having more psychiatric symptoms, as measured by the Brief Symptom Inventory (BSI), were positively associated with lending syringes. Additional prior cross-sectional studies found that social norms and psychiatric symptoms, especially depressive symptoms, were associated with needle sharing.15-18 The present study examined baseline predictors of sharing injection equipment and syringes at subsequent 6- and 12-month follow-up assessments among seropositive IDUs. Based on the findings of Metsch et al,14 it was anticipated that sharing injection equipment would be associated with age, education, drug treatment, injecting with others, peer injection norms, and psychiatric symptoms.
Participants were enrolled in the INSPIRE study, a 10-session secondary HIV prevention intervention conducted in Baltimore, Miami, New York City, and San Francisco (2001-2005). Participants were recruited from clinic and community settings. Eligibility criteria included being at least 18 years of age, confirmed HIV-positive serostatus, self-reported IDU in the prior year, sex with an opposite-sex partner in the prior 3 months, and willingness to provide oral and blood specimens. Assessments were administered by audio computer-assisted self-interview. The Centers for Disease Control and Prevention and local site Institutional Review Boards approved the study protocol. A detailed description of the INSPIRE project has been reported elsewhere.8 The overall retention rates for randomized participants were 83% and 85% at 6- and 12-month follow-up, respectively, and 91% for either visit.
Measures were based on the findings of Metsch et al14 and on the sampling distributions. Demographic variables included age, biological sex, educational attainment (having at least a high school degree), employment status, and homelessness (squat, homeless shelter, car, or street). Two questions, with a 5-point response option, assessed whether the participants thought that their friends lent needles or shared injection equipment, and 2 questions assessed whether the participant thought it was important to comply with friends' expectations about lending needles or sharing injection equipment. A composite score was created from the 4 items. Mental health was assessed by combining 3 subscales (depression, anxiety, and hostility-18 items) of the BSI (α = 0.95), which assessed psychiatric symptoms in the prior week.19 HIV primary health care visits were defined as “a visit to a doctor or medical provider to have a check up on how you're doing with your HIV or AIDS, (which may include) discussion about HIV or AIDS medications, or blood test results.” Drug abuse treatment was measured by: (1) hospital admission for drug treatment, (2) outpatient drug treatment, and (3) methadone maintenance program attendance. The dependent variable, referred to in this study as “sharing,” was defined as self-reported sharing of injection equipment (cookers, cotton, or rinse water) or lending a used syringe to individuals who were HIV-seropositive, HIV-seronegative, or of unknown serostatus at either the 6- or 12-month follow-up.
A total of 89 (of 966) participants did not return for assessments at the 6- or 12-month follow-up. Sensitivity analyses (P < 0.10) revealed that at baseline, participants who were lost to follow-up did not differ from participants who were retained on most baseline measures, including study condition, homelessness, recruitment city, health care visits, or drug treatment. Those lost to follow-up were significantly less likely to have a high school education, have an annual income below $5000, were younger, were employed, were male, and inject heroin and cocaine together.
The sample for this analysis (n = 357) was restricted to participants who met the study enrollment criteria and reported injecting drugs in the prior 3 months during the 6- or 12-month follow-up assessments. There were 486 participants who reported no IDU in the 3 months prior on either follow-up assessments and 44 individuals with missing data who were excluded from the analyses. Participants were categorized as not sharing drug equipment (n = 195) if they reported using injection drugs at 1 or more of the follow-up visits and reported not lending syringes or sharing of cookers, cottons, or rinse water.
Bivariate analyses were conducted with logistic regression models. Subsequently, a multivariable logistic regression model was constructed to test which baseline variables were associated with sharing injecting equipment at follow-up. In addition to demographic factors of sex, age, and education, the multivariable model adjusted for recruitment city and study condition. Bivariate tests indicating statistical differences at P < 0.20 were included in multivariate models. Variables no longer significant (P > 0.10) in the multivariable model were removed if the removal did not change the value of the other covariates in the model by more than 10% and were not considered to be theoretically important confounders.
Table 1 presents the number and proportion of participants who shared injection equipment at the follow-up assessments. There was a dramatic drop in self-reported injecting from 84% at baseline to 31% at 12-month follow-up, and equipment sharing reports plummeted from 45% at baseline to 12% at 12-month follow-up. There were 22% who reported injection at both follow-ups and 45% at one of the follow-ups. Table 2 presents the unadjusted and adjusted associations between baseline factors and drug equipment sharing. Engagement in medical care, as assessed by any primary HIV care services visits and any admission to a hospital for drug treatment in the past 6 months, was significantly associated with not sharing injection equipment. Peer norms supporting safer injection practices were also associated with less sharing. Lower scores on the BSI and current enrollment in methadone maintenance were marginally associated with a lower likelihood of equipment sharing. In the multivariable analyses, which adjusted for recruitment site and study condition, peer norms supporting safer injection practices, having at least 1 primary HIV medical visit, maintained statistically significant associations with reporting no equipment sharing, whereas a higher score on the BSI was associated with a significantly greater likelihood of equipment sharing.
Our findings replicate and expand on the prior cross-sectional study by Metsch et al.14 We found that baseline measures of peer norms and self-reported psychiatric symptoms, as measured by the BSI, strongly predicted sharing of injection equipment among HIV-seropositive IDUs. One difference from the prior study was that self-reported primary HIV health care visits were found to be associated with significantly less injection equipment sharing but drug abuse treatment was not. It is plausible that those IDUs who received primary HIV care had unmeasured social and economic resources that facilitate access to medical care and enable the regulation of their health behaviors, including sharing of injection equipment. An alternative explanation is that HIV illness may lead to increased health care utilization and reduced injection risk behaviors. However, we did not find that measures of HIV illness (CD4 count < 200 × 106/L) at baseline predicted sharing.
The study findings are subject to the limitations of sampling, attrition, differences in the periods between assessments and unmeasured key variables, and self-reporting biases. Many of the study participants reported that they had stopped injecting and were not included in the analyses. There were also substantially lower levels of self-reported injection risk behaviors at follow-up as compared with baseline. There are several explanations to these findings of risk reduction, including regression toward the mean. The information that all participants received about HIV prevention may have led to a reduction in sharing of injection equipment and heightened the social desirable response bias to report reduced sharing. These study limitations and changes in patterns of drug use may help to explain differences between our results and previously reported findings.
The findings have implications for HIV prevention efforts among HIV-seropositive IDUs. They underscore the need to promote social norms of not sharing injection equipment. One method of promoting risk reduction social norms is through peer outreach education and social network approaches. The findings of high BSI scores predicting sharing suggest the potential importance of addressing mental health in this population. Future studies need to examine the extent to which mental health treatment for HIV-positive IDUs may reduce their HIV transmission risk.20 Finally, these data indicate that HIV medical care utilization is linked to injection risk. Future studies should also assess this link to determine if greater engagement in HIV health care may also reduce HIV injection risk behaviors.
The INSPIRE Study Group includes the following people: Baltimore: C.A.L., A.R.K., and Karin Tobin; Miami: L.R.M., Eduardo Valverde, James Wilkinson, and Martina DeVarona; New York: M.H.L., Dave Vlahov, Phillip Coffin, Marc Gourevitch, Julia Arnsten, and Robert Gern; San Francisco: Cynthia Gomez, K.K., Carol Dawson Rose, Starley Shade, and Sonja Mackenzie; Centers for Disease Control and Prevention: David Purcell, Y.M., Scott Santibanez, Richard Garfein, and Ann O'Leary; Health Resources and Services Administration: Lois Eldred and Kathleen Handley. We would also like to acknowledge the following people for their contributions to this research: Baltimore: Susan Sherman, Roeina Marvin, Joanne Jenkins, Donald Gann, and Tonya Johnson; Miami: Clyde McCoy, Rob Malow, Wei Zhao, Lauren Gooden, Sam Comerford, Virginia Locascio, Curtis Delford, Laurel Hall, Henry Boza, Cheryl Riles, and Faye Yeomans; New York: George Fesser, Carol Gerran, and Diane Thornton; San Francisco: Caryn Pelegrino, Barbara Garcia, Jeff Moore, Erin Rowley, Debra Allen, Dinah Iglesia-Usog, Gilda Mendez, Paula Lum, and Greg Austin; Centers for Disease Control and Prevention: Gladys Ibanez, Hae-Young Kim, Toni McWhorter, Jan Moore, Lynn Paxton, and John Williamson; Centers for Disease Control and Prevention (Laboratory): Lee Lam, Jeanne Urban, Stephen Soroka, Zilma Rey, Astrid Ortiz, Sheila Bashirian, Marjorie Hubbard, Karen Tao, Bharat Parekh, and Thomas Spira.
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