Estimated HIV incidence among high-risk heterosexuals in New York City, 2007

Implementing pre-exposure prophylaxis for HIV prevention in women: the role of the obstetrician-gynecologist

Pre-exposure prophylaxis is a powerful HIV prevention tool that can reduce the risk of acquiring HIV by >90% from unprotected sex and >70% from injection drug use. The peripartum period is a time of heightened HIV risk, which underscores the need for HIV prevention counseling and the provision of biomedical interventions in all stages of a woman's reproductive life. It is important that women receive nonjudgmental care, have access to discussions of HIV risk, and are provided with pre-exposure prophylaxis counseling from their women's health practitioners. Obstetrician-gynecologists and other women's health providers are uniquely positioned to identify women who would benefit from pre-exposure prophylaxis and provide it in trusted clinical settings.

Pre-Exposure Prophylaxis (PrEP) in the Prevention of HIV: Strategies, Target Populations and Upcoming Treatments

Pre-exposure prophylaxis (PrEP) against HIV infection with tenofovir/emtricitabine is proven to be effective yet uptake of this preventive measure has been difficult due to several barriers such as cost, access, and misinformation. Certain subpopulations are disproportionately affected by this problem. Several methods have been developed to close the gap in care. New antiretroviral treatment strategies are being investigated for safety and efficacy in preventing HIV infection.

Cost-Effectiveness of Peer- Versus Venue-Based Approaches for Detecting Undiagnosed HIV Among Heterosexuals in High-Risk New York City Neighborhoods

INTRODUCTION

We used a computer simulation of HIV progression and transmission to evaluate the cost-effectiveness of a scale-up of 3 strategies to seek out and test individuals with undiagnosed HIV in New York City (NYC).

SETTING

Hypothetical NYC population.

METHODS

We incorporated the observed effects and costs of the 3 "seek and test" strategies in a computer simulation of HIV in NYC, comparing a scenario in which the strategies were scaled up with a 1-year implementation or a long-term implementation with a counterfactual scenario with no scale-up. The simulation combined a deterministic compartmental model of HIV transmission with a stochastic microsimulation of HIV progression, calibrated to NYC epidemiological data from 2003 to 2015. The 3 approaches were respondent-driven sampling (RDS) with anonymous HIV testing ("RDS-A"), RDS with a 2-session confidential HIV testing approach ("RDS-C"), and venue-based sampling ("VBS").

RESULTS

RDS-A was the most cost-effective strategy tested. When implemented for only 1 year and then stopped thereafter, using a societal perspective, the cost per quality-adjusted life-year (QALY) gained versus no intervention was $812/QALY, $18,110/QALY, and $20,362/QALY for RDS-A, RDS-C, and VBS, respectively. When interventions were implemented long term, the cost per QALY gained versus no intervention was cost-saving, $31,773/QALY, and $35,148/QALY for RDS-A, RDS-C, and VBS, respectively. When compared with RDS-A, the incremental cost-effectiveness ratios for both VBS and RDS-C were dominated.

CONCLUSIONS

The expansion of the RDS-A strategy would substantially reduce HIV-related deaths and new HIV infections in NYC, and would be either cost-saving or have favorable cost-effectiveness.

It's a Process: Reactions to HIV Diagnosis and Engagement in HIV Care among High-Risk Heterosexuals

After HIV diagnosis, heterosexuals in high-poverty urban areas evidence delays in linkage to care and antiretroviral therapy initiation compared to other groups. Yet barriers to/facilitators of HIV care among these high-risk heterosexuals are understudied. Under the theory of triadic influence, putative barriers to HIV care engagement include individual/attitudinal-level (e.g., fear, medical distrust), social-level (e.g., stigma), and structural-level influences (e.g., poor access). Participants were African-American/Black and Hispanic adults found newly diagnosed with HIV (N = 25) as part of a community-based HIV testing study with heterosexuals in a high-poverty, high-HIV-incidence urban area. A sequential explanatory mixed-methods design was used. We described linkage to HIV care and clinical outcomes [CD4 counts, viral load (VL) levels] over 1 year, and then addressed qualitative research questions about the experience of receiving a new HIV diagnosis, its effects on timely engagement in HIV care, and other barriers and facilitators. Participants were assessed five times, receiving a structured interview battery, laboratory tests, data extraction from the medical record, a post-test counseling session, and in-person/phone contacts to foster linkage to care. Participants were randomly selected for qualitative interviews (N = 15/25) that were recorded and transcribed, then analyzed using systematic content analysis. Participants were 50 years old, on average (SD = 7.2 years), mostly male (80%), primarily African-American/Black (88%), and low socioeconomic status. At the first follow-up, rates of engagement in care were high (78%), but viral suppression was modest (39%). Rates improved by the final follow-up (96% engaged, 62% virally suppressed). Two-thirds (69%) were adequately retained in care over 1 year. Qualitative results revealed multi-faceted responses to receiving an HIV diagnosis. Problems accepting and internalizing one’s HIV status were common. Reaching acceptance of one’s HIV-infected status was frequently a protracted and circuitous process, but acceptance is vital for engagement in HIV care. Fear of stigma and loss of important relationships were potent barriers to acceptance. Thus, partially as a result of difficulties accepting HIV status, delays in achieving an undetectable VL are common in this population, with serious potential negative consequences for individual and public health. Interventions to foster acceptance of HIV status are needed.

Public Health Benefit of Peer-Referral Strategies for Detecting Undiagnosed HIV Infection Among High-Risk Heterosexuals in New York City

Identifying undiagnosed HIV infection is necessary for the elimination of HIV transmission in the United States. The present study evaluated the efficacy of 3 community-based approaches for uncovering undiagnosed HIV among heterosexuals at high-risk (HHR), who are mainly African American/Black and Hispanic. Heterosexuals comprise 24% of newly reported HIV infections in the United States, but experience complex multilevel barriers to HIV testing. We recruited African American/Black and Hispanic HHR in a discrete urban area with both elevated HIV prevalence and poverty rates. Approaches tested were (1) respondent-driven sampling (RDS) and confidential HIV testing in 2 sessions (n = 3116); (2) RDS and anonymous HIV testing in one session (n = 498); and (3) venue-based sampling (VBS) and HIV testing in a single session (n = 403). The main outcome was newly diagnosed HIV infection. RDS with anonymous testing and one session reached HHR with less HIV testing experience and more risk factors than the other approaches. Furthermore, RDS with anonymous (4.0%) and confidential (1.0%) testing yielded significantly higher rates of newly diagnosed HIV than VBS (0.3%). Thus peer-referral approaches were more efficacious than VBS for uncovering HHR with undiagnosed HIV, particularly a single-session/anonymous strategy, and have a vital role to play in efforts to eliminate HIV transmission.

A Systematic Review of Published Respondent-Driven Sampling Surveys Collecting Behavioral and Biologic Data

Reporting key details of respondent-driven sampling (RDS) survey implementation and analysis is essential for assessing the quality of RDS surveys. RDS is both a recruitment and analytic method and, as such, it is important to adequately describe both aspects in publications. We extracted data from peer-reviewed literature published through September, 2013 that reported collected biological specimens using RDS. We identified 151 eligible peer-reviewed articles describing 222 surveys conducted in seven regions throughout the world. Most published surveys reported basic implementation information such as survey city, country, year, population sampled, interview method, and final sample size. However, many surveys did not report essential methodological and analytical information for assessing RDS survey quality, including number of recruitment sites, seeds at start and end, maximum number of waves, and whether data were adjusted for network size. Understanding the quality of data collection and analysis in RDS is useful for effectively planning public health service delivery and funding priorities.

Factors Associated with Recent HIV Testing among Heterosexuals at High Risk for HIV Infection in New York City

Background

The Centers for Disease Control and Prevention recommends persons at high risk for HIV infection in the United States receive annual HIV testing to foster early HIV diagnosis and timely linkage to health care. Heterosexuals make up a significant proportion of incident HIV infections (>25%) but test for HIV less frequently than those in other risk categories. Yet factors that promote or impede annual HIV testing among heterosexuals are poorly understood. The present study examines individual/attitudinal-, social-, and structural-level factors associated with past-year HIV testing among heterosexuals at high risk for HIV.

Methods

Participants were African-American/Black and Hispanic heterosexual adults (N = 2307) residing in an urban area with both high poverty and HIV prevalence rates. Participants were recruited by respondent-driven sampling in 2012–2015 and completed a computerized structured assessment battery covering background factors, multi-level putative facilitators of HIV testing, and HIV testing history. Separate logistic regression analysis for males and females identified factors associated with past-year HIV testing.

Results

Participants were mostly male (58%), African-American/Black (75%), and 39 years old on average (SD = 12.06 years). Lifetime homelessness (54%) and incarceration (62%) were common. Half reported past-year HIV testing (50%) and 37% engaged in regular, annual HIV testing. Facilitators of HIV testing common to both genders included sexually transmitted infection (STI) testing or STI diagnosis, peer norms supporting HIV testing, and HIV testing access. Among women, access to general medical care and extreme poverty further predicted HIV testing, while recent drug use reduced the odds of past-year HIV testing. Among men, past-year HIV testing was also associated with lifetime incarceration and substance use treatment.

Conclusion

The present study identified gaps in rates of HIV testing among heterosexuals at high risk for HIV, and both common and gender-specific facilitators of HIV testing. Findings suggest a number of avenues for increasing HIV testing rates, including increasing the number and types of settings offering high-quality HIV testing; promoting STI as well as HIV testing; better integrating STI and HIV testing systems; implementing peer-driven social/behavioral intervention approaches to harness the positive influence of social networks and reduce unfavorable shared peer norms; and specialized approaches for women who use drugs.

Exploring Factors Associated with Recent HIV Testing among Heterosexuals at High Risk for HIV Infection Recruited with Venue-based Sampling

Annual HIV testing is recommended for high-risk populations in the United States, to identify HIV infections early and provide timely linkage to treatment. However, heterosexuals at high risk for HIV, due to their residence in urban areas of high poverty and elevated HIV prevalence, test for HIV less frequently than other risk groups, and late diagnosis of HIV is common. Yet the factors impeding HIV testing in this group, which is predominantly African American/Black and Latino/Hispanic, are poorly understood. The present study addresses this gap. Using a systematic community-based sampling method, venue-based sampling (VBS), we estimate rates of lifetime and recent (past year) HIV testing among high-risk heterosexuals (HRH), and explore a set of putative multi-level barriers to and facilitators of recent testing, by gender. Participants were 338 HRH African American/Black and Latino/Hispanic adults recruited using VBS, who completed a computerized structured assessment battery guided by the Theory of Triadic Influence, comprised of reliable/valid measures on socio-demographic characteristics, HIV testing history, and multi-level barriers to HIV testing. Logistic regression analysis was used to identify factors associated with HIV testing within the past year. Most HRH had tested at least once (94%), and more than half had tested within the past year (58%), but only 37% tested annually. In both men and women, the odds of recent testing were similar and associated with structural factors (better access to testing) and sexually transmitted infection (STI) testing and diagnosis. Thus VBS identified serious gaps in rates of annual HIV testing among HRH. Improvements in access to high-quality HIV testing and leveraging of STI testing are needed to increase the proportion of HRH testing annually for HIV. Such improvements could increase early detection of HIV, improve the long-term health of individuals, and reduce HIV transmission by increasing rates of viral suppression.

A Latent Class Analysis of Risk Factors for Acquiring HIV Among Men Who Have Sex with Men: Implications for Implementing Pre-Exposure Prophylaxis Programs

Current Centers for Disease Control and Prevention (CDC) guidelines for prescribing pre-exposure prophylaxis (PrEP) to prevent HIV transmission are broad. In order to better characterize groups who may benefit most from PrEP, we reviewed demographics, behaviors, and clinical outcomes for individuals presenting to a publicly-funded sexually transmitted diseases (STD) clinic in Providence, Rhode Island, from 2012 to 2014. Latent class analysis (LCA) was used to identify subgroups of men who have sex with men (MSM) at highest risk for contracting HIV. A total of 1723 individuals presented for testing (75% male; 31% MSM). MSM were more likely to test HIV positive than heterosexual men or women. Among 538 MSM, we identified four latent classes. Class 1 had the highest rates of incarceration (33%), forced sex (24%), but had no HIV infections. Class 2 had <5 anal sex partners in the previous 12 months, the lowest rates of drug/alcohol use during sex and lower HIV prevalence (3%). Class 3 had the highest prevalence of HIV (7%) and other STDs (16%), > 10 anal sex partners in the previous 12 months (69%), anonymous partners (100%), drug/alcohol use during sex (76%), and prior STDs (40%). Class 4 had similar characteristics and HIV prevalence as Class 2. In this population, MSM who may benefit most from PrEP include those who have >10 sexual partners per year, anonymous partners, drug/alcohol use during sex and prior STDs. LCA is a useful tool for identifying clusters of characteristics that may place individuals at higher risk for HIV infection and who may benefit most from PrEP in clinical practice.

Strategies to uncover undiagnosed HIV infection among heterosexuals at high risk and link them to HIV care with high retention: a "seek, test, treat, and retain" study

Background

Over 50,000 individuals become infected with HIV annually in the U.S., and over a quarter of HIV infected individuals are heterosexuals. Undiagnosed HIV infection, as well as a lack of retention in care among those diagnosed, are both primary factors contributing to ongoing HIV incidence. Further, there are racial/ethnic disparities in undiagnosed HIV and engagement in care, with African Americans/Blacks and Latinos remaining undiagnosed longer and less engaged in care than Whites, signaling the need for culturally targeted intervention approaches to seek and test those with undiagnosed HIV infection, and link them to care with high retention.

Methods/Design

The study has two components: one to seek out and test heterosexuals at high risk for HIV infection, and another to link those found infected to HIV care with high retention. We will recruit sexually active African American/Black and Latino adults who have opposite sex partners, negative or unknown HIV status, and reside in locations with high poverty and HIV prevalence. The “Seek and Test” component will compare the efficacy and cost effectiveness of two strategies to uncover undiagnosed HIV infection: venue-based sampling and respondent-driven sampling (RDS). Among those recruited by RDS and found to have HIV infection, a “Treat and Retain” component will assess the efficacy of a peer-driven intervention compared to a control arm with respect to time to an HIV care appointment and health indicators using a cluster randomized controlled trial design to minimize contamination. RDS initial seeds will be randomly assigned to the intervention or control arm at a 1:1 ratio and all recruits will be assigned to the same arm as the recruiter. Participants will be followed for 12 months with outcomes assessed using medical records and biomarkers, such as HIV viral load.

Discussion

Heterosexuals do not test for HIV as frequently as and are diagnosed later than other risk groups. The study has the potential to contribute an efficient, innovative, and sustainable multi-level recruitment approach and intervention to the HIV prevention portfolio. Because the majority of heterosexuals at high risk are African American/Black or Latino, the study has great potential to reduce racial/ethnic disparities in HIV/AIDS.

Trial registration

ClinicalTrials.gov, NCT01607541, Registered May 23, 2012.

Knowledge is Power! Increased Provider Knowledge Scores Regarding Pre-exposure Prophylaxis (PrEP) are Associated with Higher Rates of PrEP Prescription and Future Intent to Prescribe PrEP

The FDA approval of emtricitabine/tenofovir disoproxil fumarate for pre-exposure prophylaxis (PrEP) in 2012 has raised questions about the delivery of PrEP in a real-world setting. iPad-based questionnaires were given to providers at conferences in California and New York to assess knowledge, experience and attitudes regarding PrEP in HIV and non-HIV providers. HIV provider status was defined either by self-identification or by having greater than 5 years of HIV care experience. Knowledge scores were the sum of correct answers from five PrEP knowledge questions. Univariate analyses used t-test to compare knowledge scores and Fisher's exact test for past or future PrEP prescription between HIV and non-HIV providers. Multivariable linear or logistic regression models were used to assess factors associated with the outcomes. Of 233 respondents, the mean age was 40 years, 59 % were White, 59 % were physicians and 52 % were HIV providers. In univariate analysis, mean PrEP knowledge scores (max 5) were significantly higher for HIV providers (2.8 versus 2.2; p < 0.001), age > 41 (mean 2.8 versus 2.3; p = 0.004), White race (2.7 versus 2.2; p = 0.026) and participants in the New York region (3.0 versus 2.3; p < 0.001). In a multivariable model of knowledge scores, all but age remained significant. Among 201 potential prescribers, the rate of prior PrEP prescription was higher among HIV providers than non-HIV providers (34 versus 9 %; p < 0.001) and by knowledge score, but the association with provider status was no longer significant in multivariable analysis that controlled for knowledge. Intent to prescribe PrEP in the future was high for all provider types (64 %) and was associated with knowledge scores in multivariable analysis. The most common concerns about PrEP (>40 % of providers) were drug toxicities, development of resistance and patient adherence to follow-up; 32 % identified risk compensation as a concern. HIV providers had significantly greater PrEP knowledge than non-HIV providers, but differences by provider type in past PrEP prescription were largely dependent on knowledge. Future PrEP prescription was also associated with knowledge, though all providers expressed greater future use. Education of potential PrEP providers will be a key component of successful PrEP implementation.

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 0.82–1.86) 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.

Risk for HIV following a diagnosis of syphilis, gonorrhoea or chlamydia: 328,456 women in Florida, 2000-2011

Several effective interventions are available for preventing HIV in women. Targeting interventions requires understanding their risk of acquiring HIV. We used surveillance data to estimate risks of HIV acquisition for 13-59-year-old women following a diagnosis of syphilis, gonorrhoea or chlamydia in Florida during 2000-2009. We excluded women reported with HIV before their STI, and measured HIV reported subsequent to STI (through 2011). Rates were compared to women with no reported STI. A total of 328,456 women had: syphilis (3325), gonorrhoea (67,784) or chlamydia (257,347). During 2,221,944 person-years of follow-up, 2118 of them were diagnosed with HIV. For women with no STI reported, during 64,763,832 person-years, 19,531 were reported with HIV. The crude rate of subsequent HIV diagnosis (per 100,000 person-years) was higher for women diagnosed with syphilis (597.9), gonorrhoea (171.3) or chlamydia (66.3) than women with no STI (30.2). Annual rates of HIV decreased over-all by 61.8% between 2001 and 2011. Women with syphilis or gonorrhoea were at highest risk for HIV and therefore might benefit from intensive counselling. However, they represented only a small fraction of the women who acquired HIV. Most cases of HIV infection among women occurred among the large group of women who were not at highest risk.

Toward an endgame: finding and engaging people unaware of their HIV-1 infection in treatment and prevention

Epidemic modeling suggests that a major scale-up in HIV treatment could have a dramatic impact on HIV incidence. This has led both researchers and policymakers to set a goal of an "AIDS-Free Generation." One of the greatest obstacles to achieving this objective is the number of people with undiagnosed HIV infection. Despite recent innovations, new research strategies are needed to identify, engage, and successfully treat people who are unaware of their infection.

HIV prevalence and risk behaviours from three consecutive surveys among men who have multiple female sexual partners in Cape Town

HIV bio-behavioural surveillance surveys conducted at regular intervals are critical for monitoring of, and informing a targeted response to the HIV pandemic. We used Respondent-driven Sampling in 2006, 2008 and 2010 to recruit men who have multiple female sexual partners. We performed several logistic regression analyses to compare HIV sexual risk behaviours, and HIV infection over time. Decreases in inconsistent condom use with main partners were not sustained in 2010. Inconsistent condom use with non-main partners, partner numbers and having one-time partners continued to decrease over time. Levels of alcohol consumption in 2010 reverted to a level higher than in 2006. Non-significant increases in HIV prevalence and reporting a symptom of a sexually transmitted infection (STI) were found. The decrease in numbers of and one-time sexual partners, and in inconsistent condom use with non-main partners augers well for decreasing HIV incidence among men in the study community, but might be offset by decreases in consistent condom use with main partners, and increases in alcohol consumption and STIs.

High HIV prevalence among low-income, Black women in New York City with self-reported HIV negative and unknown status

BACKGROUND

Black women are disproportionally affected by human immunodeficiency virus (HIV). This study investigates factors associated with newly identified HIV infection among previously self-reported HIV negative or unknown status black women living in high risk areas (HRAs) of New York City (NYC).

METHODS

Heterosexuals residing in or socially connected to NYC HRAs were recruited using respondent driven sampling for participation in the United States Centers for Disease Control-sponsored National HIV Behavioral Surveillance System in 2010. Eligible individuals were interviewed and offered an HIV test. The analysis reported here focused on black women with valid HIV results who did not report being HIV positive, and examined factors related to HIV infection in this group.

RESULTS

Of 153 black women who did not report being HIV positive at enrollment, 15 (9.8%) tested HIV positive. Age ≥40 years, ever injected drugs, and in the last 12 months had unprotected vaginal sex, exchange sex, last sex partner used crack, non-injection crack use, and non-injection heroin use were significantly associated with HIV infection (p<0.05). Only ever injected drugs (prevalence ratio: 5.1; 95% confidence interval: 2.0, 12.9) was retained in the final model.

CONCLUSIONS

Black women who had reported being either HIV negative or unaware of their serostatus had high HIV prevalence. Efforts to identify and treat HIV positive black women in HRAs should target those with a history of injection drug use. Frequent testing for HIV should be promoted in HRAs.

Feasibility of identifying a cohort of US women at high risk for HIV infection for HIV vaccine efficacy trials: longitudinal results of HVTN 906

BACKGROUND

Identifying cohorts of US women with HIV infection rates sufficient for inclusion in vaccine efficacy trials has been challenging. Using geography and sexual network characteristics to inform recruitment strategies, HVTN 906 determined the feasibility of recruiting a cohort of women at high risk for HIV acquisition.

METHODS

HIV uninfected women who reported unprotected sex in the prior 6 months, resided or engaged in risk behavior in local geographical high-risk pockets and/or had a male partner who had been incarcerated, injected drugs, or had concurrent partners were eligible. Behavioral risk assessment, HIV counseling and testing, and pregnancy testing were done at baseline, 6, 12, and 18 months.

RESULTS

Among 799 women, 71% were from local high-risk pockets and had high-risk male partners. Median age was 37 years; 79% were Black; and 15% Latina. Over half (55%) reported a new partner in the prior 6 months, 57% reported a male partner who had concurrent female sexual partners, and 37% reported a male partner who had been incarcerated. Retention at 18 months was 79.5%. Annual pregnancy incidence was 12%. Annual HIV incidence was 0.31% (95% confidence interval: 0.06% to 0.91%). Risk behaviors decreased between screening and 6 months with smaller changes thereafter.

DISCUSSION

This cohort of women recruited using new strategies based on geography and sexual network characteristics did not have an HIV incidence high enough for HIV vaccine efficacy trials, despite high baseline levels of risk and a high pregnancy rate. New strategies to identify cohorts of US women for efficacy trials are needed.

Straight talk: HIV prevention for African-American heterosexual men: theoretical bases and intervention design

In the United States, racial disparities in HIV/AIDS are stark. Although African Americans comprise an estimated 14% of the U.S. population, they made up 52% of new HIV cases among adults and adolescents diagnosed in 2009. Heterosexual transmission is now the second leading cause of HIV in the United States. African Americans made up a full two-thirds of all heterosexually acquired HIV/AIDS cases between 2005 and 2008. Few demonstrated efficacious HIV prevention interventions designed specifically for adult, African-American heterosexual men exist. Here, we describe the process used to design a theory-based HIV prevention intervention to increase condom use, reduce concurrent partnering, and increase HIV testing among heterosexually active African-American men living in high HIV prevalence areas of New York City. The intervention integrated empowerment, social identity, and rational choices theories and focused on four major content areas: HIV/AIDS testing and education; condom skills training; key relational and behavioral turning points; and masculinity and fatherhood.

HIV incidence estimate combining HIV/AIDS surveillance, testing history information and HIV test to identify recent infections in Lazio, Italy

BACKGROUND

The application of serological methods in HIV/AIDS routine surveillance systems to identify persons with recently acquired HIV infection has been proposed as a tool which may provide an accurate description of the current transmission patterns of HIV. Using the information about recent infection it is possible to estimate HIV incidence, according to the model proposed by Karon et al. in 2008, that accounts for the effect of testing practices on the number of persons detected as recently infected.

METHODS

We used data from HIV/AIDS surveillance in the period 2004-2008 to identify newly diagnosed persons. These were classified with recent/non-recent infection on the basis of an avidity index result, or laboratory evidence of recently acquired infection (i.e., previous documented negative HIV test within 6 months; or presence of HIV RNA or p24 antigen with simultaneous negative/indeterminate HIV antibody test). Multiple imputation was used to impute missing information. The incidence estimate was obtained as the number of persons detected as recently infected divided by the estimated probability of detection. Estimates were stratified by calendar year, transmission category, gender and nationality.

RESULTS

During the period considered 3,633 new HIV diagnoses were reported to the regional surveillance system. Applying the model, we estimated that in 2004-2008 there were 5,465 new infections (95%CI: 4,538-6,461); stratifying by transmission category, the estimated number of infections was 2,599 among heterosexual contacts, 2,208 among men-who-have-sex-with-men, and 763 among injecting-drug-users. In 2008 there were 952 (625-1,229) new HIV infections (incidence of 19.9 per 100,000 person-years). In 2008, for men-who-have-sex-with-men (691 per 100,000 person-years) and injecting drug users (577 per 100,000 person-years) the incidence remained comparatively high with respect to the general population, although a decreasing pattern during 2004-2008 was observed for injecting-drug-users.

CONCLUSIONS

These estimates suggest that the transmission of HIV infection in Lazio remains frequent and men-who-have-sex-with men and injecting-drug-users are still greatly affected although the majority of new infections occurs among heterosexual individuals.