Faculty Bibliography

The concept of the "risk environment"--defined as the "space ... [where] factors exogenous to the individual interact to increase the chances of HIV transmission"--draws together the disciplines of public health and geography. Researchers have increasingly turned to geographic methods to quantify dimensions of the risk environment that are both structural and spatial (e.g., local poverty rates). The scientific power of the intersection between public health and geography, however, has yet to be fully mined. In particular, research on the risk environment has rarely applied geographic methods to create neighbourhood-based measures of syringe exchange programmes (SEPs) or of drug-related law enforcement activities, despite the fact that these interventions are widely conceptualized as structural and spatial in nature and are two of the most well-established dimensions of the risk environment. To strengthen research on the risk environment, this paper presents a way of using geographic methods to create neighbourhood-based measures of (1) access to SEP sites and (2) exposure to drug-related arrests, and then applies these methods to one setting (New York City [NYC]). NYC-based results identified substantial cross-neighbourhood variation in SEP site access and in exposure to drug-related arrest rates (even within the subset of neighbourhoods nominally experiencing the same drug-related police strategy). These geographic measures--grounded as they are in conceptualizations of SEPs and drug-related law enforcement strategies--can help develop new arenas of inquiry regarding the impact of these two dimensions of the risk environment on injectors' health, including exploring whether and how neighbourhood-level access to SEP sites and exposure to drug-related arrests shape a range of outcomes among local injectors.

Pharmacies that sell over-the-counter (OTC) syringes are a major source of sterile syringes for injection drug users in cities and states where such sales are legal. In these cities and states, however, black injectors are markedly less likely to acquire syringes from pharmacies than white injectors. The present analysis documents spatial and temporal trends in OTC pharmacy access in New York City health districts over time (2001-2006) and investigates whether these trends are related to district racial/ethnic composition and to local need for OTC pharmacies. For each year of the study period, we used kernel density estimation methods to characterize spatial access to OTC pharmacies within each health district. Higher values on this measure indicate better access to these pharmacies. "Need" was operationalized using two different measures: the number of newly diagnosed injection-related AIDS cases per 10,000 residents (averaged across 1999-2001), and the number of drug-related hospital discharges per 10,000 residents (averaged across 1999-2001). District sociodemographic characteristics were assessed using 2000 US decennial census data. We used hierarchical linear models (HLM) for descriptive and inferential analyses and investigated whether the relationship between need and temporal trajectories in the Expanded Syringe Access Demonstration Program access varied by district racial/ethnic composition, controlling for district poverty rates. HLM analyses indicate that the mean spatial access to OTC pharmacies across New York City health districts was 12.71 in 2001 and increased linearly by 1.32 units annually thereafter. Temporal trajectories in spatial access to OTC pharmacies depended on both need and racial/ethnic composition. Within high-need districts, OTC pharmacy access was twice as high in 2001 and increased three times faster annually, in districts with higher proportions of non-Hispanic white residents than in districts with low proportions of these residents. In low-need districts, "whiter" districts had substantially greater baseline access to OTC pharmacies than districts with low proportions of non-Hispanic white residents. Access remained stable thereafter in low-need districts, regardless of racial/ethnic composition. Conclusions were consistent across both measures of "need" and persisted after controlling for local poverty rates. In both high- and low-need districts, spatial access to OTC pharmacies was greater in "Whiter" districts in 2001; in high-need districts, access also increased more rapidly over time in "whiter" districts. Ensuring equitable spatial access to OTC pharmacies may reduce injection-related HIV transmission overall and reduce racial/ethnic disparities in HIV incidence among injectors.

INTRODUCTION: The Centers for Disease Control and Prevention (CDC) advise repeat HIV testing for partners of HIV-infected persons; injection drug users and their sex partners; individuals with recent multiple partnerships and their sex partners; those involved in sex trade; and men who have sex with men. Additional social and behavioral variables may be useful for identifying priority populations. METHODS: We analyzed data collected during a social network study conducted in a Brooklyn, NY, neighborhood to identify social and behavioral characteristics of respondents (N = 343) involved in HIV-discordant, herpes simplex virus-2- discordant, and chlamydia-discordant partnerships. RESULTS: HIV partnership discordance was associated with injection drug use but was generally not associated with sexual behaviors including multiple partnerships and sex trade. herpes simplex virus-2 and chlamydia partnership discordance were associated with multiple partnerships, sex trade, and same sex partnership history. Additional correlates of sexually transmitted infection (STI)/HIV-discordant partnerships included older age (>or=25 years), noninjection drug use, and incarceration history. Analyses suggested that screening tools composed of CDC-recommended sexual risk and injection drug indicators plus indicators of older age, noninjection drug use, and incarceration were more effective in identifying STI/HIV priority populations than tools composed of CDC indicators alone. CONCLUSIONS: Screening tools that include social and behavioral indicators may improve STI/HIV case-finding effectiveness.

OBJECTIVE: To explore the potential utility of hepatitis C virus (HCV) seroprevalence as a biomarker for injection risk, and herpes simplex virus-2 (HSV-2) as a biomarker for sexual risk among injecting drug users (IDUs). We examined the relationships between HCV and HIV and between HSV-2 and HIV among injecting drug users in New York City relative to the large-scale implementation of syringe exchange in the mid-1990s. METHODS: 397 injecting drug users were recruited from a drug detoxification program in New York from 2005 to 2007. Informed consent was obtained, a questionnaire covering demographics, drug use and HIV risk was administered. Blood samples were tested for antibody to HIV, HCV and HSV-2. RESULTS: Among all subjects, HIV prevalence was 17%, HCV prevalence 72% and HSV-2 prevalence 48%. Among IDUs who began injecting before 1995, HIV was 28%, HCV serostatus was strongly associated with HIV serostatus (AOR=8.96, 95% CI 1.16-69.04) and HSV-2 serostatus was not associated with HIV serostatus (AOR=1.31, 95% CI 0.64-2.67). Among subjects who began injecting in 1995 or later, HIV was 6%, HCV was not associated with HIV (AOR=1.04, 95% CI 0.27-4.08) and HSV-2 serostatus was strongly related to HIV serostatus (AOR=10.71, 95% CI 1.18-97.57). CONCLUSIONS: HCV and HSV-2 HCV and HSV-2 may provide important new tools for monitoring evolving HIV epidemics among IDUs. Reconsideration of the current CDC hierarchical transmission risk classification system may also be warranted.

OBJECTIVES: We examined racial/ethnic disparities in HIV infection among injection drug users (IDUs) before and after implementation of large-scale syringe exchange programs in New York City. METHODS: Participants were recruited from IDUs entering the Beth Israel drug detoxification program in New York City. Participants (n = 1203) recruited from 1990 through 1994, prior to large-scale syringe exchange programs (pre-exchange), were compared with 1109 participants who began injecting in 1995 or later and were interviewed in 1995 through 2008 (post-exchange). RESULTS: There were large differences in HIV prevalence among pre-exchange vs post-exchange participants (African Americans, 57% vs 15%; Hispanics, 53% vs 5%; Whites, 27% vs 3%). Pre- and post-exchange relative disparities of HIV prevalence were similar for African Americans vs Whites (adjusted odds ratio [AOR] = 3.46, 95% confidence interval [CI] = 2.41, 4.96 and AOR = 4.02, 95% CI = 1.67, 9.69, respectively) and Hispanics vs Whites (AOR = 1.76, 95% CI = 1.49, 2.09 and AOR = 1.49, 95% CI = 1.02, 2.17). Racial/ethnic group differences in risk behavior did not explain differences in HIV prevalence. CONCLUSIONS: New interventions are needed to address continuing disparities in HIV infection among IDUs, but self-reported risk behaviors by themselves may not be adequate outcome measures for evaluating interventions to reduce racial/ethnic disparities in HIV infection.

This research presents estimates of HIV prevalence rates among injection drug users (IDUs) in large US metropolitan statistical areas (MSAs) during 1992-2002. Trend data on HIV prevalence rates in geographic areas over time are important for research on determinants of changes in HIV among IDUs. Such data also provide a foundation for the design and implementation of structural interventions for preventing the spread of HIV among IDUs. Our estimates of HIV prevalence rates among IDUs in 96 US MSAs during 1992-2002 are derived from four independent sets of data: (1) research-based HIV prevalence rate estimates; (2) Centers for Disease Control and Prevention Voluntary HIV Counseling and Testing data (CDC CTS); (3) data on the number of people living with AIDS compiled by the CDC (PLWAs); and (4) estimates of HIV prevalence in the US. From these, we calculated two independent sets of estimates: (1) calculating CTS-based Method (CBM) using regression adjustments to CDC CTS; and (2) calculating the PLWA-based Method (PBM) by taking the ratio of the number of injectors living with HIV to the numbers of injectors living in the MSA. We take the mean of CBM and PBM to calculate over all HIV prevalence rates for 1992-2002. We evaluated trends in IDU HIV prevalence rates by calculating estimated annual percentage changes (EAPCs) for each MSA. During 1992-2002, HIV prevalence rates declined in 85 (88.5%) of the 96 MSAs, with EAPCs ranging from -12.9% to -2.1% (mean EAPC=-6.5%; p<0.01). Across the 96 MSAs, collectively, the annual mean HIV prevalence rate declined from 11.2% in 1992 to 6.2 in 2002 (EAPC, -6.4%; p<0.01). Similarly, the median HIV prevalence rate declined from 8.1% to 4.4% (EAPC, -6.5%; p<0.01). The maximum HIV prevalence rate across the 11 years declined from 43.5% to 22.8% (EAPC, -6.7%; p<0.01). Declining HIV prevalence rates may reflect high continuing mortality among infected IDUs, as well as primary HIV prevention for non-infected IDUs and self-protection efforts by them. These results warrant further research into the population dynamics of disease progression, access to health services, and the effects of HIV prevention interventions for IDUs.