The role of syringe exchange programs and sexual identity in awareness of pre-exposure prophylaxis (PrEP) for male persons who inject drugs.

BACKGROUND: Male persons who inject drugs (male PWID) are at heightened risk for HIV, particularly if they also have sex with men. Pre-exposure prophylaxis (PrEP) could aid in HIV prevention for this population, but PrEP awareness within different sexual identities among male PWID is not well-understood. We report factors associated with greater awareness among male PWID to identify efficient means of awareness dissemination. METHODS: Data from the 2015 National HIV Behavioral Surveillance (NHBS) system cycle on injection drug use collected in New York City (NYC) were used. Bivariable analyses, using chi-squared statistics, were conducted to examine correlates of awareness of PrEP with socio-demographic, behavioral, and health care variables. Log-linked Poisson regression with robust standard errors was used to estimate adjusted prevalence ratios and determine differences in awareness of PrEP. RESULTS: Among a sample of 332 male PWID (i.e., PWID who identified as male, not transgender) we find awareness of PrEP to be low (23%) among male PWID despite 68% reporting condomless vaginal/anal sex and 32% reporting injection equipment sharing in the last twelve months. Multivariable analysis found greater PrEP awareness associated with gay or bisexual identity (aPR: 2.77, 95% CI: 1.81-4.24) and having a conversation about HIV prevention at a syringe exchange program (SEP) (aPR: 2.71, 95% CI: 1.87-3.94) to be associated with increased PrEP awareness. CONCLUSION: We found low rates of PrEP awareness among male PWID. However, our findings provide insight into information diffusion that can be utilized to increase PrEP awareness among male PWID and among all PWID. We suggest that gay and bisexual social networks and syringe exchange programs are diffusing PrEP awareness among male PWID and can be harnessed to increase PrEP awareness among male PWID.

Hepatitis C infection among men who have sex with men living with HIV in New York City, 2000-2015.

OBJECTIVES: To calculate the rate of hepatitis C virus (HCV) among HIV-infected men who have sex with men (MSM) with no reported history of injection drug use (IDU), and to assess whether disparities exist in HIV/HCV coinfection by race/ethnicity and neighbourhood poverty level within this population in New York City. METHODS: HIV-positive men who reported sex with men and did not report IDU at the time of HIV diagnosis, diagnosed through 2015 and alive as of 2000, were matched to people with HCV first reported to the New York City Department of Health and Mental Hygiene between 2000 and 2015. Those with HCV reported before or within 90 days of HIV infection were excluded. A multivariable Cox proportional hazards model was fit to compare the association between HCV diagnosis, race/ethnicity and neighbourhood poverty level. RESULTS: From 2000 to 2015, 54 488 non-IDU MSM were diagnosed with HIV, of whom 2762 (5.1%) were diagnosed with HCV after HIV diagnosis, yielding an overall age-adjusted HCV diagnosis rate of 512 per 100 000 person-years. HIV/HCV coinfection was significantly higher among non-Latino blacks (adjusted HR (aHR)=1.24, 95% CI 1.11 to 1.40) compared with non-Latino whites and among persons living in high-poverty neighbourhoods compared with those in low-poverty neighbourhoods (aHR=1.17, 95% CI 1.01 to 1.35) after stratification by year of HIV diagnosis. CONCLUSION: Disparities in HIV/HCV coinfection among HIV-positive MSM were observed by race/ethnicity and neighbourhood poverty level. Routine HCV screening is recommended for people infected with HIV. People coinfected with HIV and HCV should be linked to HCV care, treated and cured to reduce morbidity and mortality, and to avoid ongoing HCV transmission.

Combination interventions for Hepatitis C and Cirrhosis reduction among people who inject drugs: An agent-based, networked population simulation experiment.

Hepatitis C virus (HCV) infection is endemic in people who inject drugs (PWID), with prevalence estimates above 60% for PWID in the United States. Previous modeling studies suggest that direct acting antiviral (DAA) treatment can lower overall prevalence in this population, but treatment is often delayed until the onset of advanced liver disease (fibrosis stage 3 or later) due to cost. Lower cost interventions featuring syringe access (SA) and medically assisted treatment (MAT) have shown mixed results in lowering HCV rates below current levels. However. little is known about the potential cumulative effects of combining DAA and MAT treatment. While simulation experiments can reveal likely long-term effects, most prior simulations have been performed on closed populations of model agents-a scenario quite different from the open, mobile populations known to most health agencies. This paper uses data from the Centers for Disease Control's National HIV Behavioral Surveillance project, IDU round 3, collected in New York City in 2012 to parameterize simulations of open populations. To test the effect of combining DAA treatment with SA/MAT participation, multiple, scaled implementations of the two intervention strategies were simulated. Our results show that, in an open population, SA/MAT by itself has only small effects on HCV prevalence, while DAA treatment by itself can lower both HCV and HCV-related advanced liver disease prevalence. More importantly, the simulation experiments suggest that combinations of the two strategies can, when implemented together and at sufficient levels, dramatically reduce HCV incidence. We conclude that adopting SA/MAT implementations alongside DAA interventions can play a critical role in reducing the long-term consequences of ongoing HCV infection.

Exchange Sex Among Persons Who Inject Drugs in the New York Metropolitan Area: The Importance of Local Context, Gender and Sexual Identity.

Exchanging sex for money or drugs is known to increase risk for HIV among persons who inject drugs (PWID). To better understand determinants of exchange sex among PWID we examined factors associated with exchange sex in the New York metropolitan area-defined as New York City (NYC), NY; Newark, NJ; and Long Island, NY-using data from the 2012 National HIV Behavioral Surveillance system cycle on injection drug use. Of the 1160 PWID in this analysis, 24% reported exchange sex, with differences in gender and sexual identity by location. In multivariable analysis gay/bisexual men, heterosexual women, and lesbian, gay, or bisexual (LGB) women were more likely to exchange sex compared to heterosexual men. Exchange sex was also associated with race/ethnicity, homelessness, incarceration, location, and non-injection crack and cocaine use. We find that heterosexual women and LGB women who injected drugs residing in Newark were more likely to report exchange sex compared to NYC. This study highlights how local conditions impact exchange sex.

Awareness of pre-exposure prophylaxis (PrEP) among women who inject drugs in NYC: the importance of networks and syringe exchange programs for HIV prevention.

BACKGROUND: Women who inject drugs (WWID) are at heightened risk for HIV due to biological, behavioral, and structural factors. Pre-exposure prophylaxis (PrEP) could aid in HIV prevention for WWID. However, little is known about WWID awareness of PrEP, which is a necessary step that must occur before PrEP uptake. We report factors associated with greater awareness among WWID to identify efficient means of awareness dissemination. METHODS: Data from the 2015 National HIV Behavioral Surveillance (NHBS) system cycle on injection drug use collected in New York City (NYC) were used. Bivariable analyses, using chi-squared statistics, were conducted to examine correlates of awareness of PrEP with socio-demographic, behavioral, and health care variables. Multivariable logistic regression was used to estimate adjusted associations and determine differences in awareness of PrEP. RESULTS: The analysis consisted of 118 WWID. Awareness of PrEP was relatively low (31%), and risk factors were high. In the last 12 months, almost two thirds (65%) reported condomless sex, approximately one third (31%) reported transactional sex, and one third (32%) reported sharing injection equipment. In multivariable logistic regression, increased PrEP awareness was associated with reported transactional sex (AOR 3.32, 95% CI 1.22-9.00) and having a conversation about HIV prevention at a syringe exchange program (SEP) (AOR 7.61, 95% CI 2.65-21.84). We did not find race, education, household income, age, binge drinking, or sexual identity to be significantly associated with PrEP awareness. CONCLUSIONS: Large proportions of WWID were unaware of PrEP. These findings suggest that social networks (specifically sex work and SEP networks) are an efficient means for disseminating messaging about prevention materials such as PrEP. We recommend that SEP access increase, SEP processes be adopted in other health care settings, and WWID networks be utilized to increase PrEP awareness.

HIV Among MSM and Heterosexual Women in the United States: An Ecologic Analysis.

BACKGROUND: Phylogenetic studies show links between heterosexual women and men who have sex with men (MSM) that are more numerous than from heterosexual men to women suggesting that HIV infections among heterosexual women may stem from MSM. Poor communities have been associated with high rates of HIV among heterosexual women. Our analysis investigates potential transmission of HIV between MSM and female heterosexuals. METHODS: National HIV Behavioral Surveillance data describe transmission risk behaviors of MSM, and HIV case reporting data describe the percentages of cases that are attributed to transmission risk categories. We examined correlations between the percentages of men who were MSM who also have sex with women and female heterosexual cases. We also examined census data to characterize each city in terms of poverty level and race/ethnicity makeup. RESULTS: There was a high correlation (0.93) between the percentage of reported living HIV cases attributed to male heterosexual contact and female heterosexual contact and a moderate nonsignificant correlation (0.49) between the percentage of MSM who were men who have sex with men and women (MSMW) in National HIV Behavioral Surveillance and the percentage of reported cases that were attributed to female heterosexual contact suggesting some potential overlap. Cities with high levels of poverty and African American/Black residents had higher levels of MSMW and higher levels of heterosexual female cases. CONCLUSIONS: Addressing HIV in cities with high levels of MSMW may have the dual effect of improving the health of MSM populations that have a high burden of HIV and to improve the health of their larger communities.

Trends in HIV and HCV Risk Behaviors and Prevalent Infection Among People Who Inject Drugs in New York City, 2005-2012.

BACKGROUND: We assess trends in HIV and hepatitis C virus (HCV) risk behaviors and prevalent infection among people who inject drugs (PWID) in New York City (NYC). METHODS: PWID in NYC were sampled using respondent-driven sampling in 2005, 2009, and 2012 (serial cross sections) for the Centers for Disease Control and Prevention-sponsored National HIV Behavioral Surveillance study. Participants were interviewed about their current (≤12 months) risk behaviors and tested for HIV and HCV. The crude and adjusted risk ratio (RR) and 95% confidence interval (95% CI) for linear time trends were estimated using generalized estimating equations regression with a modified Poisson model. RESULTS: The sample comprised 500, 514, and 525 participants in 2005, 2009, and 2012, respectively. Significant (P < 0.05) linear trends in risk behaviors included a decline in unsafe syringe sources (60.8%, 31.3%, 46.7%; RR = 0.86, 95% CI: 0.81 to 0.92), an increase in all syringes from syringe exchanges or pharmacies (35.4%, 67.5%, 50.3%; RR = 1.15, 95% CI: 1.09 to 1.22), and an increase in condomless vaginal or anal sex (53.6%, 71.2%, 70.3%; RR = 1.14, 95% CI: 1.09 to 1.19). Receptive syringe sharing (21.4%, 27.0%, 25.1%), sharing drug preparation equipment (45.4%, 43.4%, 46.7%), and having ≥2 sex partners (51.2%, 44.0%, 50.7%) were stable. Although HIV seroprevalence declined (18.1%, 12.5%, 12.2%), HCV seroprevalence was high (68.2%, 75.8%, 67.1%). In multivariate analysis, adjusting for sample characteristics significantly associated with time, linear time trends remained significant, and the decline in HIV seroprevalence gained significance (adjusted RR = 0.76, 95% CI: 0.64 to 0.91, P = 0.003). CONCLUSIONS: This trend analysis suggests declining HIV prevalence among NYC PWID. However, HCV seroprevalence was high and risk behaviors were considerable. Longitudinal surveillance of HIV and HCV risk behaviors and infections is needed to monitor trends and for ongoing data-informed prevention among PWID.

Time Since Migration and HIV Risk Behaviors Among Puerto Ricans Who Inject Drugs in New York City.

BACKGROUND: Among people who inject drugs (PWID) in the United States, those who initiated drug injection in Puerto Rico (immigrant Puerto Rican PWID) engage in more injection and sexual risk behaviors, and have higher HIV incidence than non-Hispanic whites. OBJECTIVE: Understand the persistence of these HIV behaviors. METHODS: In a cross-sectional study conducted in New York City (NYC) in 2012 (National HIV Behavioral Surveillance), PWID aged ≥18 years were recruited using Respondent-Driven Sampling, interviewed, and tested for HIV. Participants were categorized into 5 different groups: (1) US-born non-Hispanic PWID, (2) US-born Puerto Rican PWID, (3) recent immigrant Puerto Rican PWID (≤3 years in NYC), (4) medium-term immigrant Puerto Rican PWID (>3 and ≤10 years in NYC), and (5) long-term immigrant Puerto Rican PWID (>10 years in NYC). We examined the relationship between time since migrating on sexual and injection risk behaviors among immigrant Puerto Rican PWID, compared with U.S.-born Puerto Rican PWID and US-born non-Hispanic PWID. Adjusted odds ratios (aOR) and 95% confidence intervals (95% CI) were estimated using logistic regression. RESULTS: A total of 481 PWID were recruited. In adjusted analyses using US-born non-Hispanic PWID as the comparison group, syringe sharing was significantly more likely among medium-term immigrants; and unprotected sex with casual partners was more likely among recent and long-term immigrants. CONCLUSIONS: The risk-acculturation process for immigrant Puerto Rican PWID may be nonlinear and may not necessarily lead to risk reduction over time. Research is needed to better understand this process.

Community Sexual Bridging Among Heterosexuals at High-Risk of HIV in New York City.

Community sexual bridging may influence the socio-geographic distribution of heterosexually transmitted HIV. In a cross-sectional study, heterosexual adults at high-risk of HIV were recruited in New York City (NYC) in 2010 for the Centers for Disease Control and Prevention-sponsored National HIV Behavioral Surveillance system. Eligible participants were interviewed about their HIV risk behaviors and sexual partnerships and tested for HIV. Social network analysis of the geographic location of participants' recent sexual partnerships was used to calculate three sexual bridging measures (non-redundant ties, flow-betweenness and walk-betweenness) for NYC communities (defined as United Hospital Fund neighborhoods), which were plotted against HIV prevalence in each community. The analysis sample comprised 494 participants and 1534 sexual partnerships. Participants were 60.1 % male, 79.6 % non-Hispanic black and 19.6 % Hispanic race/ethnicity; the median age was 40 years (IQR 24-50); 37.7 % had ever been homeless (past 12 months); 16.6 % had ever injected drugs; in the past 12 months 76.7 % used non-injection drugs and 90.1 % engaged in condomless vaginal or anal sex; 9.6 % tested HIV positive (of 481 with positive/negative results). Sexual partnerships were located in 33 (78.6 %) of 42 NYC communities, including 13 "high HIV-spread communities", 7 "hidden bridging communities", 0 "contained high HIV prevalence communities", and 13 "latent HIV bridging communities". Compared with latent HIV bridging communities, the population racial/ethnic composition was more likely (p < 0.0001) to be black or Hispanic in high HIV-spread communities and to be black in hidden bridging communities. High HIV-spread and hidden bridging communities may facilitate the maintenance and spread of heterosexually transmitted HIV in black and Hispanic populations in NYC.

Bisexual Behavior Among Male Injection Drug Users in New York City.

Drug using men who have sex with men and women (MSMW) may be at high risk for HIV infection and transmitting HIV to sex partners. In 2012, injection drug users (IDUs) were sampled in New York City for the National HIV Behavioral Surveillance cross-sectional study using respondent-driven sampling. Logistic regression was used to calculate crude and adjusted odds ratios (aOR) and 95 % confidence intervals (95 %CI) to determine correlates of bisexual behavior in the past 12 months. Of 333 participants, 47(14.1 %) reported MSMW. Variables independently associated (p < 0.05) with MSMW included bisexual sexual identity (vs. "straight") (adjusted odds ratio (aOR) 92.6; 95 % CI 18.9, 454.5), Bronx residence [vs. Manhattan (aOR 8.4; 95 %CI 1.6,43.7)], past 12 month behaviors of having sex with ≥3 sex partners (aOR 18.1; 95 % CI 3.3,98.4), "sold" sex (aOR 8.5; 95 % CI 2.3, 31.5), "bought" sex (aOR 0.2; 95 % CI 0.1, 0.9), and injection methamphetamine use (aOR 20.5; 95 % CI 3.0, 139.7). MSM IDUs are an important subgroup to consider for HIV interventions, as they may not be reached through HIV prevention programming aimed at MSM.

Constructing a representative sample of out-of-care HIV patients from a representative sample of in-care patients.

Individuals infected with HIV who are out of care are at a higher risk of HIV-related morbidity and mortality. It has been difficult to recruit a representative sample of out-of-care patients for epidemiological studies. Using a novel weighting method, we constructed a representative sample of out-of-care HIV patients from a representative sample of in-care patients. In-care patients were weighted based on the probability of receiving care during the study period and the probability of selection to participate in the study, and out-of-care patients were represented by those who were previously out of care and recently returned. The method can be used in other patient populations, if every patient in the population has a known, non-zero probability of receiving care and a known, non-zero probability of participating in the study.

It's Never Just HIV: Exposure to an HIV Prevention Media Campaign and Behavior Change Among Men Who Have Sex with Men Participating in the National HIV Behavioral Surveillance System in New York City.

PURPOSE: The aim of this study was to assess the exposure to and impact of the It's Never Just HIV mass media campaign aimed at HIV negative men who have sex with men (MSM) in New York City. METHODS: Questions about the campaign were included in the local questionnaire of the Centers for Disease Control and Prevention (CDC)-sponsored National HIV Behavioral Surveillance (NHBS) study of MSM in NYC conducted in 2011. Participants in this cross-sectional study were recruited using venue-based sampling. RESULTS: Among 447 NYC National HIV Behavioral Surveillance study participants who self-reported HIV negative or unknown status and answered questions about the NYC Department of Health and Mental Hygiene's It's Never Just HIV campaign, more than one-third (n = 173, 38.7%) reported having seen the campaign. Latinos (34.8%) and blacks (34.4%) were less likely to report seeing the campaign compared to whites (47.7%). Most of those who reported seeing the campaign saw it on the subway (80.1%). Only 9.4% of those who saw the campaign reported having changed their sexual or health behaviors in response to the campaign. CONCLUSIONS: These data suggest that thousands of HIV-uninfected MSM in NYC have been reached by the campaign and recalled its message.

Experiences of Discrimination and HIV Risk Among Men Who Have Sex With Men in New York City.

The extent of gay-related discrimination in New York City (NYC) and the demographic and behavioral factors correlated with experiences of gay-related discrimination are not well understood. The Centers for Disease Control and Prevention-sponsored National HIV Behavioral Surveillance System, a cross-sectional study, was conducted in NYC in 2011. Men who have sex with men were venue-sampled, interviewed, and offered HIV testing. Frequencies of types of gay-related discrimination experienced in the past 12 months were calculated. Associations between types of discrimination and demographic and HIV risk variables were examined through the estimation of prevalence ratios (PRs) and 95% confidence intervals (CIs). More than half (53.2%) of all study participants reported having experienced any gay-related discrimination in the past 12 months; 45.0% reported that they had been called names or insulted; 23.6% reported receiving poorer services than other people in restaurants, stores, other businesses, or agencies; 22.0% reported being treated unfairly at work or school; 15.1% reported being physically attacked or injured; and 6.7% reported being denied or given lower quality health care. HIV-positive status (adjusted PR [aPR] = 2.9; 95% CI = 1.5, 5.6) and drug use in the past 12 months (aPR = 0.3; 95% CI = 0.1, 0.7) were independently associated with reports of having been denied or given lower quality health care. High rates of reported gay-related discrimination suggest that greater efforts are needed to reduce gay-related discrimination in affected communities. Future research is needed to better understand the extent of gay-related discrimination in NYC, particularly with regard to the relationship between HIV status and health care access.

HIV-related stigma in a New York City sample of adults in outpatient care for HIV infection: a short report.

This analysis used data from a randomly selected cross-sectional sample of HIV infected outpatient adults in New York City to assess HIV-related stigma and examine gender-specific differences among factors associated with HIV-related stigma. Data was collected by conducting participant interviews and medical records abstraction. HIV-related stigma was assessed using the internalized AIDS-related stigma scale (IA-RSS). Exploratory factor analysis of the IA-RSS indicated that the scale consisted of two factors: (1) internalized stigma and (2) anticipated stigma. Of the 447 sampled participants 23.9% had a higher level of internalized stigma and 38.3% had a higher level of anticipated stigma. Multivariate analysis indicated that among females, internalized stigma was associated with being diagnosed HIV positive after the introduction of HAART in 1996 (adjusted prevalence ratio [PR]: 1.9; 95% CI: 1.2, 3.1; P < 0.01) and a diagnosis of depression (adjusted PR: 1.9; 95% CI: 1.2, 2.9; P < 0.01). Among males, anticipated stigma was associated with younger age (18 and 39 years) (adjusted PR: 1.7; 95% CI: 1.3, 2.2; P < 0.001) and use of non-injection drugs (adjusted PR: 0.60; 95% CI: 0.41, 0.86; P < 0.01). Findings suggest that there may be gender-specific differences among factors associated with different dimensions of HIV-related stigma.

Correlates of selling sex among male injection drug users in New York City.

BACKGROUND: Compared to female IDUs, the correlates of receiving money, drugs, or other things in exchange for sex ("selling sex") among male IDUs are not well understood. METHODS: In 2012, IDUs were sampled in New York City for the National HIV Behavioral Surveillance cross-sectional study using respondent driven sampling. Analyses were limited to male participants. Logistic regression was used to calculate crude and adjusted odds ratios (aOR) and 95% confidence intervals (95% CI) to determine the correlates of selling sex to (1) men and (2) women in the past 12 months. RESULTS: Of 394 males, 35 (8.9%) sold sex to men and 66 (16.8%) sold sex to women. Correlates of selling sex to men included bisexual/gay identity (aOR: 31.0; 95% CI: 8.1, 119.1), Bronx residence (vs. Manhattan) (aOR: 38.1; 95% CI: 6.2, 235.5), and in the past 12 months, being homeless (aOR: 9.9; 95% CI: 2.0, 49.6), ≥3 sex partners (aOR: 26.2; 95% CI: 4.7, 147.6), non-injection cocaine use (aOR: 5.4; 95% CI: 1.6, 18.2), and injecting methamphetamine (aOR: 36.9; 95% CI: 5.7, 240.0). Correlates of selling sex to women included, in the past 12 months, ≥3 sex partners (aOR: 14.6; 95% CI: 6.6, 31.9), binge drinking at least once a week (aOR: 3.1; 95% CI: 1.6, 6.1), non-injection crack use (aOR: 3.3; 95% CI: 1.6, 6.7), most frequently injected "speedball" (vs. heroin) (aOR: 2.1; 95% CI: 1.1, 4.2), and receptively shared syringes (aOR: 2.4; 95%CI: 1.2, 4.8). CONCLUSIONS: Among male IDUs, those who sold sex had more sex partners, which may facilitate the sexual spread of HIV among IDUs and to non-IDU male and female sex partners. HIV prevention interventions aimed at male IDUs who sell sex should consider both their sexual and parenteral risks and the greater risk of engaging in exchange sex associated with the use of injection and non-injection stimulant drugs.

Multilevel risk factors for greater HIV infection of black men who have sex with men in New York City.

BACKGROUND: There is a large and disproportionate burden of HIV in black men who have sex with men (MSM) which is not adequately explained by racial/ethnic differences in risk behaviors. However, social factors may account for this disparity in HIV infection. We examine the extent to which both individual risk behaviors and social factors reduce the effect of black race and may account for the disparity in HIV infection of black MSM. METHODS: In a cross-sectional study in New York City in 2011, MSM were venue sampled, interviewed, and HIV tested. Variables associated (P < 0.10) both with black race and testing HIV positive were analyzed using multivariate logistic regression. RESULTS: Of 416 participants who were HIV tested and did not self-report being positive, 19.5% were black, 41.1% were Hispanic, 30.5% were white, and 8.9% were of other race/ethnicity. Overall, 8.7% tested positive (24.7% of blacks, 7.6% of Hispanics, 1.0% of whites, and 5.4% of other). The effect of black race versus non-black race/ethnicity with testing HIV positive declined by 49.2%, (crude odds ratio, 6.5 [95% confidence interval, 3.2-13.3] vs. adjusted odds ratio, 3.3 [95% confidence interval, 1.5-7.5]), after adjustment for having a black last sex partner, not having tested for HIV in the past 12 months, Brooklyn residency, and having an annual income less than US$20,000. CONCLUSIONS: Greater HIV infection risk of black MSM may result from social factors and less frequent HIV testing than from differences in risk behaviors. To reduce the disparity in HIV infection of black MSM, multilevel interventions that both ameliorate social risk factors and increase the frequency of HIV testing are needed.

Trends in HIV prevalence and risk behavior among men who have sex with men in New York City, 2004-2011.

This study examined trends in HIV prevalence and HIV-related risk behaviors from 2004 through 2011 among men who have sex with men (MSM) in New York City. MSM were venue-sampled, interviewed, and offered HIV testing in serial cross-sectional studies. Significant differences in overall time trends were determined using the Spearman rank correlation and logistic regression models. There were 457 (2004-2005), 550 (2008), and 510 (2011) participants in each study round. There was no significant trend in HIV prevalence over time, and past 12 month unprotected anal intercourse remained steady. However, drug use and number of sex partners declined. Among those who did not self-report being HIV positive, the percentage that tested for HIV in the past 12 months increased. The results from this study suggest that from 2004 through 2011 more MSM in New York City are being tested for HIV and have declining drug use and fewer sex partners.

Spatial recruitment bias in respondent-driven sampling: Implications for HIV prevalence estimation in urban heterosexuals.

Respondent-driven sampling (RDS) is a study design used to investigate populations for which a probabilistic sampling frame cannot be efficiently generated. Biases in parameter estimates may result from systematic non-random recruitment within social networks by geography. We investigate the spatial distribution of RDS recruits relative to an inferred social network among heterosexual adults in New York City in 2010. Mean distances between recruitment dyads are compared to those of network dyads to quantify bias. Spatial regression models are then used to assess the impact of spatial structure on risk and prevalence outcomes. In our primary distance metric, network dyads were an average of 1.34 (95 % CI 0.82­1.86) miles farther dispersed than recruitment dyads, suggesting spatial bias. However, there was no evidence that demographic associations with HIV risk or prevalence were spatially confounded. Therefore, while the spatial structure of recruitment may be biased in heterogeneous urban settings, the impact of this bias on estimates of outcome measures appears minimal.

Prevalence of HIV infection and risk behaviors among younger and older injecting drug users in the United States, 2009.

This study compared HIV sero-prevalence and risk behaviors between younger and older injecting drug users (IDUs). IDUs aged ≥18 years were interviewed for the 2009 National HIV Behavioral Surveillance System. Using GEE regression, we assessed characteristics of younger (18-29 years) and older (≥30 years) IDUs, and factors associated with past 12-month receptive syringe sharing and unprotected sex (vaginal/anal). Of 10,090 participants, 10 % were younger. HIV sero-prevalence was lower among younger than older IDUs (4 vs. 10 %, p = 0.001). Younger IDUs were more likely (p ≤ 0.002) to be non-black race/ethnicity, report higher household income, homelessness, being arrested and to engage in receptive syringe sharing and unprotected sex. In multivariable models, age remained associated (p < 0.001) with receptive syringe sharing (aPR = 1.14, 95 % CI1.07-1.22) and unprotected sex (aPR = 1.10, 95 % CI1.06-1.14). Although younger IDUs had lower HIV prevalence, their behaviors place them at increased risk of HIV infection and could lead to a rapid spread in this susceptible population.

Syringe access, syringe sharing, and police encounters among people who inject drugs in New York City: a community-level perspective.

BACKGROUND: Injection drug user (IDU) experience and perceptions of police practices may alter syringe exchange program (SEP) use or influence risky behaviour. Previously, no community-level data had been collected to identify the prevalence or correlates of police encounters reported by IDUs in the United States. METHODS: New York City IDUs recruited through respondent-driven sampling were asked about past-year police encounters and risk behaviours, as part of the National HIV Behavioural Surveillance study. Data were analysed using multiple logistic regression. RESULTS: A majority (52%) of respondents (n=514) reported being stopped by police officers; 10% reported syringe confiscation. In multivariate modelling, IDUs reporting police stops were less likely to use SEPs consistently (adjusted odds ratio [AOR]=0.59; 95% confidence interval [CI]=0.40-0.89), and IDUs who had syringes confiscated may have been more likely to share syringes (AOR=1.76; 95% CI=0.90-3.44), though the finding did not reach statistical significance. CONCLUSIONS: Findings suggest that police encounters may influence consistent SEP use. The frequency of IDU-police encounters highlights the importance of including contextual and structural measures in infectious disease risk surveillance, and the need to develop approaches harmonizing structural policing and public health.