Samuel R. Friedman

Audio-computer interviewing to measure risk behaviour for HIV among injecting drug users: a quasi-randomised trial.

BACKGROUND We aimed to assess audio-computer-assisted self-interviewing (audio-CASI) as a method of reducing under-reporting of HIV risk behaviour among injecting drug users. METHODS Injecting drug users were interviewed at syringe-exchange programmes in four US cities. Potential respondents were randomly selected from participants in the syringe exchanges, with weekly alternate assignment to either traditional face-to-face interviews or audio-CASI. The questionnaire included items on sociodemographic characteristics, drug use, and HIV risk behaviours for 30 days preceding the interview. We calculated odds ratios for the difference in reporting of HIV risk behaviours between interview methods. FINDINGS 757 respondents were interviewed face-to-face, and 724 were interviewed by audio-CASI. More respondents reported HIV risk behaviours and other sensitive behaviours in audio-CASI than in face-to-face interviews (odds ratios for reporting of rented or bought used injection equipment in audio-CASI vs face-to-face interview 2.1 [95% CI 1.4-3.3] p=0.001; for injection with borrowed used injection equipment 1.5 [1.1-2.2] p=0.02; for renting or selling used equipment 2.3 [1.3-4.0] p=0.003). INTERPRETATION Although validation of these self-reported behaviours was not possible, we propose that audio-CASI enables substantially more complete reporting of HIV risk behaviour. More complete reporting might increase understanding of the dynamics of HIV transmission and make the assessment of HIV-prevention efforts easier.

HIV incidence among injecting drug users in New York City syringe-exchange programmes

BACKGROUND There have been no studies showing that participation in programmes which provide legal access to drug-injection equipment leads to individual-level protection against incident HIV infection. We have compared HIV incidence among injecting drug users participating in syringe-exchange programmes in New York City with that among non-participants. METHODS We used meta-analytic techniques to combine HIV incidence data from injecting drug users in three studies: the Syringe Exchange Evaluation (n = 280), in which multiple interviews and saliva samples were collected from participants at exchange sites; the Vaccine Preparedness initiative cohort (n = 133 continuing exchanges and 188 non-exchangers, in which participants were interviewed and tested for HIV every 3 months; and very-high-seroprevalence cities in the National AIDS Demonstration Research (NADR) programme (n = 1029), in which street-recruited individuals were interviewed and tested for HIV every 6 months. In practice, participants in the NADR study had not used syringe exchanges. FINDINGS HIV incidence among continuing exchange-users in the Syringe Exchange Evaluation was 1.58 per 100 person-years at risk (95% CI 0.54, 4.65) and among continuing exchange-users in the Vaccine Preparedness Initiative it was 1.38 per 100 person-years at risk (0.23, 4.57). Incidence among non-users of the exchange in the Vaccine Preparedness Initiative was 5.26 per 100 person-years at risk (2.41, 11.49), and in the NADR cities, 6.23 per 100 person-years at risk (4.4, 8.6). In a pooled-data, multivariate proportional-hazards analysis, not using the exchanges was associated with a hazard ratio of 3.35 (95% CI 1.29, 8.65) for incident HIV infection compared with using the exchanges. INTERPRETATION We observed an individual-level protective effect against HIV infection associated with participation in a syringe-exchange programme. Sterile injection equipment should be legally provided to reduce the risk of HIV infection in persons who inject illicit drugs.

Sociometric risk networks and risk for HIV infection.

OBJECTIVES This study examined whether networks of drug-injecting and sexual relationships among drug injectors are associated with individual human immunodeficiency virus (HIV) serostatus and with behavioral likelihood of future infection. METHODS A cross-sectional survey of 767 drug injectors in New York City was performed with chain-referral and linking procedures to measure large-scale (sociometric) risk networks. Graph-theoretic algebraic techniques were used to detect 92 connected components (drug injectors linked to each other directly or through others) and a 105-member 2-core within a large connected component of 230 members. RESULTS Drug injectors in the 2-core of the large component were more likely than others to be infected with HIV. Seronegative 2-core members engaged in a wide range of high-risk behaviors, including engaging in risk behaviors with infected drug injectors. CONCLUSIONS Sociometric risk networks seem to be pathways along which HIV travels in drug-injecting peer groups. The cores of large components can be centers of high-risk behaviors and can become pockets of HIV infection. Preventing HIV from reaching the cores of large components may be crucial in preventing widespread HIV epidemics.

HIV Incidence Among Injection Drug Users in New York City, 1990 to 2002: Use of Serologic Test Algorithm to Assess Expansion of HIV Prevention Services

OBJECTIVES We sought to estimate HIV incidence among injection drug users (IDUs) in New York City from 1990 to 2002 to assess the impact of an expansion of syringe exchange services. Syringe exchange increased greatly during this period, from 250,000 to 3,000,000 syringes exchanged annually. METHODS Serum samples were obtained from serial cross-sectional surveys of 3,651 IDUs. HIV-positive samples were tested with the Serologic Test Algorithm for Recent HIV Seroconversion (STARHS) assay to identify recent HIV infections and to estimate HIV incidence. Consistency with other incidence studies was used to assess strengths and limitations of STARHS. RESULTS HIV incidence declined from 3.55/100 person-years at risk (PYAR) from 1990-1992, to 2.63/100 PYAR from 1993-1995, to 1.05/100 PYAR from 1996-1998, and to 0.77/100 PYAR from 1999-2002 (P<.001). There was a very strong negative linear relationship (r= -.99, P<.005) between the annual numbers of syringes exchanged and estimated HIV incidence. These results were highly consistent with a large number of shorter incidence studies among IDUs conducted during the time period. CONCLUSIONS STARHS testing of samples from large serial cross-sectional surveys can provide important data for the assessment of community-level HIV prevention.

Reductions in hepatitis C virus and HIV infections among injecting drug users in New York City, 1990-2001

Objective:To assess trends in HIV, hepatitis C virus (HCV) and HIV/HCV infection among injecting drug users (IDU) from 1990 to 2001 in New York City. The 1990–2001 time period included a very large expansion of syringe exchange in New York City, from 250 000 to 3 000 000 syringes exchanged annually. Methods:Cross-sectional seroprevalence surveys of IDU entering drug abuse treatment in New York City, with sample sizes for HCV of 72 in 1990–1991 and 412 in 2000–2001. A structured risk behavior questionnaire was administered, and HIV and HCV testing were conducted. HCV testing was performed on de-linked stored serum samples. Results:Over the 1990–2001 period, HIV prevalence declined from 54 to 13%. HCV prevalence declined from 80 to 59% among HIV-seronegative individuals, and from 90 to 63% overall. The estimated HCV incidence in 2000–2001 among new injectors was 18 per 100 person-years at risk. Conclusions:The large-scale expansion of syringe exchange was temporally associated with large reductions in both HIV and HCV prevalence. The prevalence and incidence of HCV, however, still remain at high levels among IDU in New York City.

Social networks, risk-potential networks, health, and disease.

Driven in part by recent research in the epidemiology and prevention of human immunodeficiency virus/acquired immunodeficiency syndrome (HIV/AIDS) and other sexually transmitted or blood-borne infections, the topic of social networks has become the focus of considerable interest and discussion. Networks offer the promise of a way to move the analytic focus one step “above” that of the individual, to consider the patterns through which individuals are linked in small groups and through them in large “sociometric” networks. Thus, network approaches offer a way to apply the analytic insights and computerized techniques of systems theories to studies of the flow of social support, social influence, and infectious diseases through populations and, as well, among organizations. Before going on, though, it might be useful to explain what a network is, what kinds of networks are of most interest, and what some key terms used in network analysis are. This can be done in mathematical language, such that a network is a set of nodes plus the set of connections linking some or all of these nodes to each other. It might be more useful, however, to use a few diagrams to explain these concepts in specific contexts relevant to the study of health and disease.

High-risk personal networks and syringe sharing as risk factors for HIV infection among new drug injectors.

In a cross-sectional study of 174 new injecting drug users (IDUs) in New York City who had injected for < or = 6 years, we examined whether those who both share syringes and have personal risk networks that include high-risk injectors are particularly likely to be infected with HIV. Subjects were street recruited between July 1991 and January 1993, were interviewed about their risk behaviors in the prior 2 years and their personal risk networks with other IDUs in the prior 30 days, and were tested for HIV; 20% were HIV seropositive. Among those who both shared syringes and had a personal risk network member who injected more than once a day, 40% were HIV seropositive (versus 14% for others, p < 0.001). In simultaneous multiple logistic regression, the interaction of both sharing syringes and having a personal risk network member who injected more than once a day remained independently and significantly associated with being HIV seropositive (OR, 3.57; 95% CI, 1.22, 10.43; p < 0.020), along with Latino race/ethnicity and exchanging sex for money or drugs. These findings suggest that the combination of sharing syringes with having a high-risk personal network is a risk factor for HIV infection among new IDUs. Studies of risk factors for HIV infection among new IDUs and interventions to reduce the spread of HIV among them should focus on their risk networks as well as their risk behaviors.

Transmission and prevention of HIV and sexually transmitted infections in war settings: implications for current and future armed conflicts.

We review the effects of war on HIV and STI transmission and critically appraise short- and medium-term approaches to prevention. Our intent is to stimulate thinking about the potential for increased HIV/STI transmission in current and future armed conflicts with particular reference to Afghanistan and to encourage timely interventions to prevent a worsening HIV epidemic in Central and South Asia. (excerpt)

Syringe-mediated drug-sharing (backloading) : a new risk factor for HIV among injecting drug users

Background:In syringe-mediated drug-sharing (backloading), injecting drug users (IDU) use their syringes to mix drugs and to give measured shares to other IDU by squirting drug solution into the syringes of other IDU. Backloading has been discussed as a potential HIV risk factor, but its role as an HIV transmission route has not been established empirically. Methods:Six hundred and sixty IDU who had injected drugs in the previous 2 years were street-recruited from Bushwick, New York City through chain referral, tested for HIV antibody and interviewed about sexual and drug-risk behaviors. Results:Receiving drugs via backloading in the previous 2 years was reported by 24.5% of the subjects. These subjects had significantly higher HIV seroprevalence than those who did not receive drugs by backloading (odds ratio, 2.2; 95% confidence interval, 1.5–3.1). Backloading remained positively and significantly associated with HIV seropositivity in stepwise logistic regression, and in a series of simultaneous logistic models controlling for sociodemographic variables and for sexual and drug risk variables. Conclusions:Backloading can be a route of HIV transmission among IDU and should be incorporated into risk-factor studies and HIV transmission modeling. Many IDU who avoid other high-risk drug-injection practices may overlook the risk of backloading. HIV prevention programs should warn IDU against syringe-mediated drug-sharing and work together to develop ways to avoid it. AIDS 1993, 7:1653–1660

Transitions to injecting drug use among noninjecting heroin users: social network influence and individual susceptibility.

Objectives: To determine the incidence/predictors of transitions to injecting among noninjecting heroin users (NIUs). Methods: Street-recruited NIUs in New York City, March/1996-March/2003, were interviewed for a prospective cohort study about social network influence (communication promoting injecting; exposure to injectors) and individual susceptibility. A transition to injecting was the first drug injection following baseline. Hazards ratios (HRs) (P < 0.05) were estimated by Cox proportional hazards regression, stratified by baseline injecting history. Results: Of 369 (64% of 579) followed, former-injectors were more likely to transition to injecting (33% or 53/160 vs. 12% or 25/209; 16.0/100 person-years-at-risk [pyar] vs. 4.6/100 pyar; HR = 3.25). Independent predictors among never-injectors included using ≥2 bags of heroin daily (HR = 7.0); social network influence (communication) and homelessness (HR = 6.3); shorter-term heroin use (HR = 5.3); social network influence (exposure) and physically abused (HR = 4.7); friends approve/condone drug injecting (HR = 3.5); lower perceived social distance from injectors (HR = 2.9); and younger age at first heroin use (HR = 1.2). Independent predictors among former-injectors were social network influence (communication) and lower perceived social distance from injectors (HR = 3.4); white race/ethnicity (HR = 2.0); not very afraid of needles (HR = 1.8); and younger age (HR = 1.1). Conclusions: The risk of initiating injecting was lower than the risk of resuming injecting. Social network influence facilitates transitioning to injecting among those susceptible. Interventions to prevent injecting should address both social network influence and individual susceptibility.