Expanding HAART treatment to all currently eligible individuals under the 2008 IAS-USA Guidelines in British Columbia, Canada

Longitudinal Analysis of HIV Risk and Substance Use Patterns for Men Who Have Sex with Men and Women and Men Who Have Sex with Men Only

Men Who Have Sex with Men and Women (MSMW) experience discrimination from same-sex and heterosexual communities partially because of perceptions they feature high-risk sexual behavior, elevated polysubstance use levels, and constitute an HIV bridge population. We used a longitudinal multivariate generalized linear mixed model comparing sexual risk and substance use patterns for Men Who Have Sex with Men Only (MSMO) with MSMW in the same cohort study. Data consisted of 771 men reporting 3,705 sexual partnerships from 2012-2017. For high-risk sexual behavior multivariate results showed non-significant (p>0.05) differences for partner number and commercial sex work, and significantly less (p<0.05) HIV prevalence and condomless anal sex. However, MSMW had significantly higher levels of hallucinogen and prescription opioid use, and substance treatment histories. Only one HIV-positive MSMW had a transmittable viral load, negating the concept of an HIV bridge population. Results indicate the need for additional longitudinal studies comparing MSMO and MSMW.

Crystal Methamphetamine Use and Initiation among Gay, Bisexual, and Other Men Who Have Sex with Men Living with HIV in a Treatment as Prevention Environment

Risk compensation in an HIV Treatment as Prevention (TasP) environment may increase high-risk sexual and substance use behaviors among people living with HIV. Objective: To examine recent crystal methamphetamine (CM) use/initiation in a longitudinal cohort of gay, bisexual, and other men who have sex with men (GBMSM) living with HIV in Metro Vancouver, Canada. Methods: Eligible participants were GBMSM aged >15 years who reported sex with another man in the past six months. Participants were recruited using respondent-driven sampling and self-completed a computer questionnaire every six months. We used multi-level generalized mixed-effect models to evaluate trends in recent CM use (past six months), multivariable logistic regression to identify covariates of recent CM use, and multivariable survival analysis to identify predictors of CM initiation. Results: Of 207 GBMSM living with HIV at enrollment, 44.3% reported recent CM use; there was a statistically non-significant decrease over the study period (41% in first period to 25% in final period, p = 0.087). HIV treatment optimism was not associated with CM use/initiation. CM use was positively associated with depressive symptomology, sexual escape motivation, transactional sex, number of anal sex partners, condomless anal sex with seroconcordant partners, STIs, and other substance use. Recent CM use was negatively associated with viral load sorting. CM initiation was predicted by escape motivation, transactional sex, and group sex participation. Conclusion: Results suggest that CM use among GBMSM living with HIV is prevalent and increased CM use/initiation is not a consequence of TasP public policy.

Mobile Health Intervention to Reduce HIV Transmission: A Randomized Trial of Behaviorally Enhanced HIV Treatment as Prevention (B-TasP)

OBJECTIVES

We conducted a randomized clinical trial to test a mobile health behavioral intervention designed to enhance HIV treatment as prevention (B-TasP) by simultaneously increasing combination antiretroviral therapies (cART) adherence and improving the sexual health of people living with HIV.

METHODS

A cohort of sexually active men (n = 383) and women (n = 117) living with HIV were enrolled. Participants were baseline assessed and randomized to either (1) B-TasP adherence and sexual health intervention or (2) general health control intervention. Outcome measures included HIV RNA viral load, cART adherence monitored by unannounced pill counts, indicators of genital tract inflammation, and sexual behaviors assessed over 12 months.

RESULTS

Eighty-six percent of the cohort was retained for 12-month follow-up. The B-TasP intervention demonstrated significantly lower HIV RNA, OR = 0.56, P = 0.01, greater cART adherence, Wald χ = 33.9, P = 0.01, and fewer indicators of genital tract inflammation, Wald χ = 9.36, P = 0.05, over the follow-up period. Changes in sexual behavior varied, with the B-TasP intervention showing lower rates of substance use in sexual contexts, but higher rates of condomless sex with non-HIV positive partners occurred in the context of significantly greater beliefs that cART reduces HIV transmission.

CONCLUSIONS

Theory-based mobile health behavioral interventions can simultaneously improve cART adherence and sexual health in people living with HIV. Programs aimed to eliminate HIV transmission by reducing HIV infectiousness should be bundled with behavioral interventions to maximize their impact and increase their chances of success.

HIV treatment optimism and crystal methamphetamine use and initiation among HIV-negative men who have sex with men in Vancouver, Canada: A longitudinal analysis

BACKGROUND

Treatment as Prevention (TasP) leading to increased HIV treatment optimism among men who have sex with men (MSM) has been previously associated with behavioural risk compensation, though not yet via crystal methamphetamine (CM) use. Among HIV-negative MSM in a TasP environment, this study aimed to investigate the prevalence of recent CM use over time, examine the association between HIV treatment optimism and CM use and initiation, and identify correlates of recent CM use and predictors of CM initiation.

METHODS

Using data from a prospective behavioural cohort study of sexually active MSM in the Vancouver area, we used multi-level generalized mixed effect models to evaluate temporal trends in CM use, univariable and multivariable logistic regression to identify covariates of recent CM use, and univariable and multivariable survival analysis to identify predictors of CM initiation.

RESULTS

Of 497 HIV-negative cohort participants, 10.3% reported any recent CM use at enrollment. From 2012-2016, there were no statistically significant temporal trends in overall CM use or with routes of administration. In multivariable logistic regression analyses, HIV treatment optimism was not associated with recent CM use (not retained in final model) or CM initiation (aHR = 1.06, 95% CI:0.98-1.15). Significant correlates of CM use include recent gamma-hydroxybutyrate (GHB) and ecstasy use, and having received/given drugs for sex.

CONCLUSIONS

Among HIV-negative MSM in Vancouver, HIV treatment optimism does not appear to be independently associated with CM use or initiation of use, though use of CM was both prevalent and stable over time.

Seroadaptive Strategies of Vancouver Gay and Bisexual Men in a Treatment as Prevention Environment

British Columbia's treatment as prevention policy has provided free access to highly active antiretroviral therapy (HAART) to all HIV-positive provincial residents since 1996. One outcome is an increase in HIV-positive gay and bisexual men (GBM) with suppressed viral loads. Previous cross-sectional analyses indicated that some Vancouver GBM now recognize condomless anal sex with men on HAART who report a suppressed viral load as a seroadaptive strategy. To test the hypothesis that this new strategy, termed viral load sorting (VLS), is recognized and used among by GBM in the Momentum Health Study, we analyzed longitudinal data for HIV-negative/unknown (n = 556) and HIV-positive (n = 218) serostatus participants. Analyses indicated that both groups reported VLS, and that serostatus and Treatment Optimism Scale scores were significant determinants in frequency and use. Results exemplify the medicalization of sex and Rogers' Diffusion Of Preventative Innovations Model, and they have important implications for HIV research and GBM sexual decision-making.

Prescription Opioid Injection Among HIV-Positive People Who Inject Drugs in a Canadian Setting

Prescription opioids (POs) are commonly prescribed to patients living with HIV/AIDS, while the illicit use of POs remains a major public health concern throughout Canada and the United States. We sought to identify the prevalence and correlates of PO injection among HIV-positive people who inject drugs (PWID) in Vancouver, Canada, where HIV/AIDS treatment and care is offered at no cost. We examined data from 634 individuals from an ongoing prospective cohort of HIV-positive PWID. Between December 2005 and November 2013, the median prevalence of recent PO injection was 24.2 % [interquartile range (IQR): 21.5-25.8 %]. In a multivariable generalized estimating equation model, Caucasian ethnicity, heroin injection, and drug dealing were positively associated with PO injection, while older age and methadone maintenance treatment were negatively associated with PO injection (all p < 0.05). Engagement on antiretroviral therapy was inversely associated with PO injection in a bivariable analysis, but did not remain significant after adjusting for heroin injection. These findings describe a particularly vulnerable sub-group of PWID who may benefit from targeted efforts to both minimize drug-related risk behaviors and support HIV/AIDS treatment.

Non-HIV-related health care utilization, demographic, clinical and laboratory factors associated with time to initial retention in HIV care among HIV-positive individuals linked to HIV care

OBJECTIVES

The aim of the study was to explore non-HIV-related health care service (NHRHS) utilization, demographic, clinical and laboratory factors associated with timely initial "retention" in HIV care among individuals "linked" to HIV care in British Columbia (BC), Canada.

METHODS

We conducted a Weibull time-to-initial-retention analysis among BC Seek and Treat for Optimal Prevention of HIV/AIDS (STOP HIV/AIDS) cohort participants linked in 2000-2010, who had ≥ 1 year of follow-up. We defined "linked" as the first HIV-related service accessed following HIV diagnosis and "retained" as having, within a calendar year, either: (i) at least two HIV-related physician visits/diagnostic tests or (ii) at least two antiretroviral therapy (ART) dispensations, ≥ 3 months apart. Individuals were followed until they were retained, died, their last contact date, or until 31 December 2011, whichever occurred first.

RESULTS

Of 5231 linked individuals (78% male; median age 39: (Q1-Q3: 32-46) years], 4691 (90%) were retained [median time to initial retention of 9 (Q1-Q3: 5-13) months] by the end of follow-up and 540 (10%) were not. Eighty-four per cent of not retained and 96% of retained individuals used at least one type of NHRHS during follow-up. Individuals who saw a specialist for NHRHS during follow-up had a shorter time to initial retention than those who did not [adjusted hazard ratio (aHR) 2.79; 95% confidence interval (CI): 2.47-3.16]. However, those who saw a general practitioner (GP) for NHRHS (aHR 0.79; 95% CI: 0.74-0.84) and those admitted to the hospital for NHRHS (aHR 0.60; 95% CI: 0.54-0.67), versus those who did/were not, respectively, had longer times to initial retention, as did female patients, people who inject drugs (PWID) and individuals < 40 years old.

CONCLUSIONS

Overall, 84% of not retained individuals used some type of NHRHS during follow-up. Given that 71% of not retained individuals used GP NHRHS, our results suggest that GP-targeted interventions may be effective in improving time to initial retention.

A socio-ecological perspective of access to and acceptability of HIV/AIDS treatment and care services: a qualitative case study research

Background

Access to healthcare is an essential element of health development and a fundamental human right. While access to and acceptability of healthcare are complex concepts that interact with different socio-ecological factors (individual, community, institutional and policy), it is not known how these factors affect HIV care. This study investigated the impact of socio-ecological factors on access to and acceptability of HIV/AIDS treatment and care services (HATCS) in Wolaita Zone of Ethiopia.

Method

Qualitative case study research was conducted in six woredas (districts). Focus group discussions (FGDs) were conducted with 68 participants in 11 groups (six with people using antiretroviral therapy (ART) and five with general community members). Key informant interviews (KIIs) were conducted with 28 people involved in HIV care, support services and health administration at different levels. Individual in-depth interviews (IDIs) were conducted with eight traditional healers and seven defaulters from (ART). NVIVO 10 was used to assist qualitative content data analysis.

Results

A total of 111 people participated in the study, of which 51 (45.9 %) were male and 60 (54.1 %) were female, while 58 (53.3 %) and 53 (47.7 %) were urban and rural residents, respectively. The factors that affect access to and acceptability of HATCS were categorized in four socio-ecological units of analysis: client-based factors (awareness, experiences, expectations, income, employment, family, HIV disclosure and food availability); community-based factors (care and support, stigma and discrimination and traditional healing); health facility-based factors (interactions with care providers, availability of care, quality of care, distance, affordability, logistics availability, follow up and service administration); and policy and standards (healthcare financing, service standards, implementation manuals and policy documents).

Conclusions

A socio-ecological perspective provides a useful framework to investigate the interplay among multilevel and interactive factors that impact on access to and acceptability of HATCS such as clients, community, institution and policy. Planners, resource allocators and implementers could consider these factors during planning, implementation and evaluation of HATCS. Further study is required to confirm the findings.

Electronic supplementary material

The online version of this article (doi:10.1186/s12889-016-2830-6) contains supplementary material, which is available to authorized users.

HIV stigma and the experiences of young men with voluntary and routine HIV testing

As routine HIV testing approaches are implemented to enhance participation rates in HIV testing, it is often widely believed that these approaches are socially and ethically justifiable given the underlying assumption that these practices will result in the widespread reduction of HIV-related stigma. Nonetheless, a variety of empirical and theoretical gaps on how HIV testing practices may impact on HIV stigma remain, raising questions about the social underpinnings of the public health rationale. We draw on 50 interviews with 18-24 year-old men to determine how HIV-related stigma is experienced differentially across subgroups of young men in relation to both voluntary and routine testing practices. The men's experiences with routine testing highlight how (mis)interpretations of universal, routine testing practices may serve to (unintentionally) burden disadvantaged subgroups of men; however, when these practices are adequately explicated, the universal dimension of a routine offer greatly diminished these concerns. These findings also show that, under the right conditions, a routine offer can provide transformative opportunities for individuals to reconceptualise their expectations over HIV and HIV-related stigma.

The 'Expanded HIV care in opioid substitution treatment' (EHOST) cluster-randomized, stepped-wedge trial: A study protocol

The public health response to HIV/AIDS has turned its focus onto optimizing health care system delivery to maximize case identification, access and sustained engagement in antiretroviral treatment (ART). Opioid Agonist Treatment (OAT) provides a critical opportunity for HIV testing and linkage to ART. The EHOST study is a cluster-randomized, stepped-wedge trial to evaluate a prescriber-focused intervention to increase HIV testing rates, and optimize ART engagement and retention outcomes among individuals engaged in OAT. The study will encompass all drug treatment clinics currently admitting patients for the treatment of opioid use disorder across the province of British Columbia, encompassing an estimated 90% of the OAT caseload. The trial will be executed over a 24-month period, with groups of clinics receiving the intervention in 6-month intervals. Evaluation of the proposed intervention's effectiveness will focus on three primary outcomes: (i) the HIV testing rate among those not known to be HIV positive; (ii) the rate of ART initiation among those not on ART; and (iii) the rate of ART continuation among those on ART. A difference-in-differences analytical framework will be applied to estimate the intervention's effect. This approach will assess site-specific changes in primary outcomes across clusters while adjusting for potential residual heterogeneity in patient case mix, volume, and quality of care across clinics. Statistical analysis of outcomes will be conducted entirely with linked population-level administrative health datasets. Facilitated by established collaborations between key stakeholders across the province, the EHOST intervention promises to optimize HIV testing and care within a marginalized and hard-to-reach population.

Health prevention in the era of biosocieties: a critical analysis of the 'Seek-and-Treat' paradigm in HIV/AIDS prevention

On 18 November 2014, the United Nations launched an urgent new campaign to end AIDS as a global health threat by 2030. With its proposed strategy, the UN follows leading scientists who had declared the failure of former prevention strategies and now were promoting a 'Seek and Treat for Optimal Prevention' (STOP) approach as the most cost-effective response to the pandemic to meet the goal of 'an AIDS-free generation'. STOP combines antiretroviral therapy and routine HIV screening to find persons unaware that they are HIV-positive, because research has shown that people consistently change their behaviour (i.e. increase condom use, have fewer partners) after an HIV diagnosis. AIDS activists have broadly criticized this strategy on different levels. In this article, we go beyond these criticisms and try to analyse the political rationalities behind this 'new' strategy. We believe that it is necessary to put the rationale underpinning the STOP programme into the context of broader societal transformations that can best be captured as the development of advanced liberal societies and the new emphasis on self-controlling or self-responsibility rather than on disciplining behaviour.

The Impact of Implementing a Test, Treat and Retain HIV Prevention Strategy in Atlanta among Black Men Who Have Sex with Men with a History of Incarceration: A Mathematical Model

BACKGROUND

Annually, 10 million adults transition through prisons or jails in the United States (US) and the prevalence of HIV among entrants is three times higher than that for the country as a whole. We assessed the potential impact of increasing HIV Testing/Treatment/Retention (HIV-TTR) in the community and within the criminal justice system (CJS) facilities, coupled with sexual risk behavior change, focusing on black men-who-have-sex-with-men, 15-54 years, in Atlanta, USA.

METHODS

We modeled the effect of a HIV-TTR strategy on the estimated cumulative number of new (acquired) infections and mortality, and on the HIV prevalence at the end of ten years. We additionally assessed the effect of increasing condom use in all settings.

RESULTS

In the Status Quo scenario, at the end of 10 years, the cumulative number of new infections in the community, jail and prison was, respectively, 9246, 77 and 154 cases; HIV prevalence was 10815, 69 and 152 cases, respectively; and the cumulative number of deaths was 2585, 18 and 34 cases, respectively. By increasing HIV-TTR coverage, the cumulative number of new infections could decrease by 15% in the community, 19% in jail, and 8% in prison; HIV prevalence could decrease by 8%, 9% and 7%, respectively; mortality could decrease by 20%, 39% and 18%, respectively. Based on the model results, we have shown that limited use and access to condoms have contributed to the HIV incidence and prevalence in all settings.

CONCLUSIONS

Aggressive implementation of a CJS-focused HIV-TTR strategy has the potential to interrupt HIV transmission and reduce mortality, with benefit to the community at large. To maximize the impact of these interventions, retention in treatment, including during the period after jail and prison release, and increased condom use was vital for decreasing the burden of the HIV epidemic in all settings.

Cohort Profile: HAART Observational Medical Evaluation and Research (HOMER) cohort

Since 1986, antiretroviral therapy (ART) has been available free of charge to individuals living with HIV in British Columbia (BC), Canada, through the BC Centre of Excellence in HIV/AIDS (BC-CfE) Drug Treatment Program (DTP). The Highly Active Antiretroviral Therapy (HAART) Observational Medical Evaluation and Research (HOMER) cohort was established in 1996 to maintain a prospective record of clinical measurements and medication profiles of a subset of DTP participants initiating HAART in BC. This unique cohort provides a comprehensive data source to investigate mortality, prognostic factors and treatment response among people living with HIV in BC from the inception of HAART. Currently over 5000 individuals are enrolled in the HOMER cohort. Data captured include socio-demographic characteristics (e.g. sex, age, ethnicity, health authority), clinical variables (e.g. CD4 cell count, plasma HIV viral load, AIDS-defining illness, hepatitis C co-infection, mortality) and treatment variables (e.g. HAART regimens, date of treatment initiation, treatment interruptions, adherence data, resistance testing). Research findings from the HOMER cohort have featured in numerous high-impact peer-reviewed journals. The HOMER cohort collaborates with other HIV cohorts on both national and international scales to answer complex HIV-specific research questions, and welcomes input from external investigators regarding potential research proposals or future collaborations. For further information please contact the principal investigator, Dr Robert Hogg (robert_hogg@sfu.ca).

High levels of heterogeneity in the HIV cascade of care across different population subgroups in British Columbia, Canada

Background

The HIV cascade of care (cascade) is a comprehensive tool which identifies attrition along the HIV care continuum. We executed analyses to explicate heterogeneity in the cascade across key strata, as well as identify predictors of attrition across stages of the cascade.

Methods

Using linked individual-level data for the population of HIV-positive individuals in BC, we considered the 2011 calendar year, including individuals diagnosed at least 6 months prior, and excluding individuals that died or were lost to follow-up before January 1^st, 2011. We defined five stages in the cascade framework: HIV ‘diagnosed’, ‘linked’ to care, ‘retained’ in care, ‘on HAART’ and virologically ‘suppressed’. We stratified the cascade by sex, age, risk category, and regional health authority. Finally, multiple logistic regression models were built to predict attrition across each stage of the cascade, adjusting for stratification variables.

Results

We identified 7621 HIV diagnosed individuals during the study period; 80% were male and 5% were <30, 17% 30–39, 37% 40–49 and 40% were ≥50 years. Of these, 32% were MSM, 28% IDU, 8% MSM/IDU, 12% heterosexual, and 20% other. Overall, 85% of individuals ‘on HAART’ were ‘suppressed’; however, this proportion ranged from 60%–93% in our various stratifications. Most individuals, in all subgroups, were lost between the stages: ‘linked’ to ‘retained’ and ‘on HAART’ to ‘suppressed’. Subgroups with the highest attrition between these stages included females and individuals <30 years (regardless of transmission risk group). IDUs experienced the greatest attrition of all subgroups. Logistic regression results found extensive statistically significant heterogeneity in attrition across the cascade between subgroups and regional health authorities.

Conclusions

We found that extensive heterogeneity in attrition existed across subgroups and regional health authorities along the HIV cascade of care in B.C., Canada. Our results provide critical information to optimize engagement in care and health service delivery.

Process monitoring of an HIV treatment as prevention program in British Columbia, Canada

BACKGROUND

In light of accumulated scientific evidence of the secondary preventive benefits of antiretroviral therapy, a growing number of jurisdictions worldwide have formally started to implement HIV Treatment as Prevention (TasP) programs. To date, no gold standard for TasP program monitoring has been described. Here, we describe the design and methods applied to TasP program process monitoring in British Columbia (BC), Canada.

METHODS

Monitoring indicators were selected through a collaborative and iterative process by an interdisciplinary team including representatives from all 5 regional health authorities, the BC Centre for Disease Control (BCCDC), and the BC Centre for Excellence in HIV/AIDS (BC-CfE). An initial set of 36 proposed indicators were considered for inclusion. These were ranked on the basis of 8 criteria: data quality, validity, scientific evidence, informative power of the indicator, feasibility, confidentiality, accuracy, and administrative requirement. The consolidated list of indicators was included in the final monitoring report, which was executed using linked population-level data.

RESULTS

A total of 13 monitoring indicators were included in the BC TasP Monitoring Report. Where appropriate, indicators were stratified by subgroups of interest, including HIV risk group and demographic characteristics. Six Monitoring Reports are generated quarterly: 1 for each of the regional health authorities and a consolidated provincial report.

CONCLUSIONS

We have developed a comprehensive TasP process monitoring strategy using evidence-based HIV indicators derived from linked population-level data. Standardized longitudinal monitoring of TasP program initiatives is essential to optimize individual and public health outcomes and to enhance program efficiencies.

Cohort profile: Seek and treat for the optimal prevention of HIV/AIDS in British Columbia (STOP HIV/AIDS BC)

The Seek and Treat for Optimal Prevention of HIV/AIDS (STOP HIV/AIDS) cohort is a census of all identified HIV-positive individuals in the province of British Columbia. It was formed through the linkage of nine provincial treatment, surveillance and administrative databases. This open cohort allows for bidirectional analyses from 1996 onward and is refreshed annually. Extensive data collection for cohort members includes demographic information, detailed clinical and laboratory data, complete prescription drug use including antiretroviral agents, and information on health service utilization encompassing inpatient and outpatient care, addictions treatment and palliative care. This cohort provides an unprecedented opportunity to evaluate, over an extended time period, patterns and determinants of key outcomes including engagement in the cascade of HIV care from diagnosis to treatment to viral suppression as well as monitoring trends in medical costs, health outcomes and other key healthcare delivery indicators at a population level with wide-ranging, high-quality data. The overall purpose of these activities is to enable the development and implementation of strategically targeted interventions to improve access to testing, care and treatment for all HIV-positive individuals living in British Columbia.

The impact of HIV treatment as prevention in the presence of other prevention strategies: lessons learned from a review of mathematical models set in resource-rich countries

OBJECTIVE

We aimed to assess the potential prevention benefits of HIV treatment as prevention (TasP) in resource-rich countries and examine the potential interactions between TasP and other prevention strategies by reviewing mathematical models of TasP.

METHOD

Multiple databases were searched for mathematical models published in the previous 5 years (from July 2007 to July 2012). The nine models located were set in Canada, Australia and the United States.

RESULTS

These models' predictions suggested that the impact of expanding treatment rates on expected new infections could range widely, from no decrease to a decrease of 76%, depending on the time horizon, assumptions and the form of TasP modeled. Increased testing, reducing sexually transmitted infections and reducing risky practices were also predicted to be important strategies for decreasing expected new infections. Sensitivity analysis suggests that current uncertainties such as the effectiveness of highly active antiretroviral therapy outside of heterosexual transmission, less than ideal adherence, and risk compensation, could impact on the success of TasP at the population level.

CONCLUSION

The results from large scale pilots and community randomized controlled trials will be useful in demonstrating how well this prevention approach works in real world settings, and in identifying the factors that are needed to support its effectiveness.

HIV treatment as prevention: the key to an AIDS-free generation

The presence of elevated HIV viral load within blood and genital secretions is a critical driver of transmission events. Long-term suppression of viral load to undetectable levels through the use of antiretroviral therapy is now standard practice for clinical management of HIV. Antiretroviral therapy therefore can play a key role as a means to curb HIV transmission. Results of a randomized clinical trial, in conjunction with several observational studies, have now confirmed that antiretroviral therapy markedly decreases HIV transmission risk. Mathematical models and population-based ecologic studies suggest that further expansion of antiretroviral coverage within current guidelines can play a major role in controlling the spread of HIV. Expansion of so-called "Treatment as Prevention" initiatives relies upon maximal uptake of the HIV continuum-of-care cascade to allow for successful identification of those not yet known to be HIV-infected, engagement of patients in appropriate care, and subsequently achieving sustained virologic suppression in patients with the use of antiretroviral therapy. Since 2010, the Joint United Nations AIDS (UNAIDS) program has called for the inclusion of antiretroviral treatment as a key pillar in the global strategy to control the spread of HIV infection. This has now been invigorated by the release of the World Health Organization's 2013 Consolidated Antiretroviral Therapy Guidelines, recommending treatment to be offered to all HIV-infected individuals with CD4 cell counts below 500/mm³, and, regardless of CD4 cell count, to serodiscordant couples, TB and HBV co-infected individuals, pregnant women, and children below the age of 5 years.

Optimizing the engagement of care cascade: a critical step to maximize the impact of HIV treatment as prevention

PURPOSE OF REVIEW

At present, data from mathematical models, ecologic studies and a clinical trial demonstrate that use of combination antiretroviral therapy (cART) can markedly reduce HIV transmission. Expansion of cART uptake (Treatment as Prevention) is a critical component of biomedical interventions to prevent HIV transmission.

RECENT FINDINGS

Successful implementation is dependent on identifying undiagnosed individuals, linking and retaining them in care and initiating durable and potent cART regimens. This continuum is encapsulated within the framework of the 'Test and Treat', or 'Seek, Test, Treat and Retain' strategies. Currently only 19-28% of all HIV-infected individuals in the USA are estimated to be virologically suppressed.

SUMMARY

Optimizing the engagement of care cascade represents a critical step to maximize the individual and societal impact of cART and therefore deliver on the promise of HIV Treatment as Prevention.

HIV incidence in men who have sex with men in England and Wales 2001-10: a nationwide population study

Background

Control of HIV transmission could be achievable through an expansion of HIV testing of at-risk populations together with ready access and adherence to antiretroviral therapy. To examine whether increases in testing rates and antiretroviral therapy coverage correspond to the control of HIV transmission, we estimated HIV incidence in men who have sex with men (MSM) in England and Wales since 2001.

Methods

A CD4-staged back-calculation model of HIV incidence was used to disentangle the competing contributions of time-varying rates of diagnosis and HIV incidence to observed HIV diagnoses. Estimated trends in time to diagnosis, incidence, and undiagnosed infection in MSM were interpreted against a backdrop of increased HIV testing rates and antiretroviral-therapy coverage over the period 2001–10.

Findings

The observed 3·7 fold expansion in HIV testing in MSM was mirrored by a decline in the estimated mean time-to-diagnosis interval from 4·0 years (95% credible interval [CrI] 3·8–4·2) in 2001 to 3·2 years (2·6–3·8) by the end of 2010. However, neither HIV incidence (2300–2500 annual infections) nor the number of undiagnosed HIV infections (7370, 95% CrI 6990–7800, in 2001, and 7690, 5460–10 580, in 2010) changed throughout the decade, despite an increase in antiretroviral uptake from 69% in 2001 to 80% in 2010.

Interpretation

CD4 cell counts at HIV diagnosis are fundamental to the production of robust estimates of incidence based on HIV diagnosis data. Improved frequency and targeting of HIV testing, as well as the introduction of ART at higher CD4 counts than is currently recommended, could begin a decline in HIV transmission among MSM in England and Wales.

Funding

UK Medical Research Council, UK Health Protection Agency.

Application and validation of case-finding algorithms for identifying individuals with human immunodeficiency virus from administrative data in British Columbia, Canada

OBJECTIVE

To define a population-level cohort of individuals infected with the human immunodeficiency virus (HIV) in the province of British Columbia from available registries and administrative datasets using a validated case-finding algorithm.

METHODS

Individuals were identified for possible cohort inclusion from the BC Centre for Excellence in HIV/AIDS (CfE) drug treatment program (antiretroviral therapy) and laboratory testing datasets (plasma viral load (pVL) and CD4 diagnostic test results), the BC Centre for Disease Control (CDC) provincial HIV surveillance database (positive HIV tests), as well as databases held by the BC Ministry of Health (MoH); the Discharge Abstract Database (hospitalizations), the Medical Services Plan (physician billing) and PharmaNet databases (additional HIV-related medications). A validated case-finding algorithm was applied to distinguish true HIV cases from those likely to have been misclassified. The sensitivity of the algorithms was assessed as the proportion of confirmed cases (those with records in the CfE, CDC and MoH databases) positively identified by each algorithm. A priori hypotheses were generated and tested to verify excluded cases.

RESULTS

A total of 25,673 individuals were identified as having at least one HIV-related health record. Among 9,454 unconfirmed cases, the selected case-finding algorithm identified 849 individuals believed to be HIV-positive. The sensitivity of this algorithm among confirmed cases was 88%. Those excluded from the cohort were more likely to be female (44.4% vs. 22.5%; p<0.01), had a lower mortality rate (2.18 per 100 person years (100PY) vs. 3.14/100PY; p<0.01), and had lower median rates of health service utilization (days of medications dispensed: 9745/100PY vs. 10266/100PY; p<0.01; days of inpatient care: 29/100PY vs. 98/100PY; p<0.01; physician billings: 602/100PY vs. 2,056/100PY; p<0.01).

CONCLUSIONS

The application of validated case-finding algorithms and subsequent hypothesis testing provided a strong framework for defining a population-level cohort of HIV infected people in BC using administrative databases.

Assessing the effectiveness of antiretroviral regimens in cohort studies involving HIV-positive injection drug users

OBJECTIVE

We compared the effectiveness of different highly active antiretroviral therapy (HAART) regimens considering, separately, history of injection drug use (IDU) (yes/no). DESIGN, METHODS: A total of 1163 HIV-infected patients initiated HAART between 1 January 2000 and 28 February 2009 in British Columbia, Canada, and were followed until 28 February 2010. HAART effectiveness was measured by the ability to achieve viral suppression below 50 copies/ml at 6 months. We compared HAART regimens containing efavirenz and boosted atazanavir. We developed logistic regression models using different techniques to control for potential confounders.

RESULTS

Among the 1163 patients, 796 (68%) achieved viral suppression at 6 months (32% reporting a history of IDU). Different confounding models yielded very similar odds ratios for achieving viral suppression. Boosted atazanavir-based HAART demonstrated to be the most effective regimen, showing a surprisingly higher benefit for patients with a history of IDU (odds ratios from different models ranged from 1.74-1.95 to 1.45-1.51).

CONCLUSIONS

The literature has conflicting results regarding the effectiveness of HAART to treat HIV infection among those with a history of IDU. We have shown that most patients, with and without a history of IDU, were able to achieve viral suppression at 6 months. Boosted atazanavir-based HAART was the most resilient regimen and it was more effective than efavirenz-based HAART among IDUs. Given the limited inclusion of IDU in clinical trials of HAART's efficacy, a randomized clinical trial comparing different first-line HAART regimens among IDU is warranted based on these results.

Mediators of antiretroviral adherence: a multisite international study

The purpose of this study was to investigate the effects of stressful life events (SLE) on medication adherence (3 days, 30 days) as mediated by sense of coherence (SOC), self-compassion (SCS), and engagement with the healthcare provider (eHCP) and whether this differed by international site. Data were obtained from a cross-sectional sample of 2082 HIV positive adults between September 2009 and January 2011 from sites in Canada, China, Namibia, Puerto Rico, Thailand, and US. Statistical tests to explore the effects of stressful life events on antiretroviral medication adherence included descriptive statistics, multivariate analysis of variance, analysis of variance with Bonferroni post-hoc analysis, and path analysis. An examination by international site of the relationships between SLE, SCS, SOC, and eHCP with adherence (3 days and 30 days) indicated these combined variables were related to adherence whether 3 days or 30 days to different degrees at the various sites. SLE, SCS, SOC, and eHCP were significant predictors of adherence past 3 days for the United States (p = < 0.001), Canada (p = 0.006), and Namibia (p = 0.019). The combined independent variables were significant predictors of adherence past 30 days only in the United States and Canada. Engagement with the provider was a significant correlate for antiretroviral adherence in most, but not all, of these countries. Thus, the importance of eHCP cannot be overstated. Nonetheless, our findings need to be accompanied by the caveat that research on variables of interest, while enriched by a sample obtained from international sites, may not have the same relationships in each country.

Reaping the prevention benefits of highly active antiretroviral treatment: policy implications of HIV Prevention Trials Network 052

PURPOSE OF REVIEW

This review explores the policy implications of findings from the HIV Prevention Trials Network (HPTN 052) treatment as prevention (TasP) study.

RECENT FINDINGS

To date, the potential of antiretrovirals to prevent sexual transmission of HIV by infected persons has been grounded in observational cohort, ecological, mathematical modeling, and meta-analytic studies. HPTN 052 represents the first randomized controlled trial to test the secondary prevention benefit of HIV transmission using antiretroviral treatment in largely asymptomatic persons with high CD4 cell counts.

SUMMARY

The US National HIV/AIDS Strategy has among its key goals the reduction of incident HIV infections, improved access to quality care and associated outcomes, and the reduction in HIV-associated health disparities and inequities. HPTN 052 demonstrates that providing TasP, in combination with other effective prevention strategies offers the promise of achieving these life-saving goals. But HPTN 052 also highlights the need for cautious optimism and underscores the importance of addressing current gaps in the HIV prevention, treatment, and care continuum in order for 'TasP' strategies to achieve their full potential. Among these are necessary improvements in the capacity to expand HIV testing, facilitate effective linkage and retention in care, and improve treatment initiation, maintenance, and virus suppression.

How long do physicians wait to start antiretroviral treatment in newly diagnosed HIV-infected patients?

OBJECTIVE

With the aim to look for possible ways to reduce individual time from HIV diagnosis to low viraemia and reduced infectivity, we measured time between HIV diagnosis and treatment initiation in a large prospective cohort.

METHODS

We selected patients initiating care from 2005 to 2010 in 8 French clinical cohorts. Median time from HIV diagnosis to treatment initiation was estimated by log rank, and baseline characteristics related with this duration were analyzed using a multivariate Cox model.

RESULTS

Median time from HIV diagnosis to treatment initiation was 8 months in 3,422 patients enrolled in this study and 15 in 215 patients with no straightaway indication. The clinical center in which patients seek care, year of diagnosis, and route of infection were associated with time to treatment initiation.

CONCLUSION

Only 6.2% of the population presented to care with no treatment indication. The median time between diagnosis and treatment initiation was 15 months in this population, and this time period was notably growing shorter each year.

Sexual HIV transmission and antiretroviral therapy: a prospective cohort study of behavioral risk factors among men and women living with HIV/AIDS

BACKGROUND

Using antiretroviral therapies for HIV prevention relies on patient adherence and avoidance of co-occurring sexually transmitted infections.

PURPOSE

The objective of this study is to simultaneously examine HIV treatment adherence and sexual risks for HIV transmission.

METHODS

This study is a prospective cohort of 201 men and 55 women diagnosed with HIV/AIDS infection.

RESULTS

A total of 32% men and 39% women engaged in unprotected intercourse with at least one HIV negative or unknown HIV status sex partner over 12 months. Nearly half (46%) of participants with HIV negative or unknown HIV status unprotected sex partners had detectable HIV viral load and were significantly more likely to have contracted a sexually transmitted infection since their HIV diagnosis. Individuals at higher risk for transmitting HIV were also less adherent to antiretroviral therapies.

CONCLUSIONS

Programs that aim to use antiretroviral therapies for HIV prevention require careful attention to adherence, sexually transmitted co-infections, and substance use.

Treatment for prevention of HIV transmission in a localised epidemic: the case for South Australia

BACKGROUND

Discussion is currently taking place among international HIV/AIDS groups around increasing HIV testing and initiating earlier use of antiretroviral therapy (ART) among people diagnosed with HIV as a method to reduce the spread of HIV. In this study, we explore the expected epidemiological impact of this strategy in a small population in which HIV transmission is predominantly confined to men who have sex with men (MSM).

METHODS

A deterministic mathematical transmission model was constructed to investigate the impacts of strategies that increase testing and treatment rates, and their likely potential to mitigate HIV epidemics among MSM. Our novel model distinguishes men in the population who are more easily accessible to prevention campaigns through engagement with the gay community from men who are not. This model is applied to the population of MSM in South Australia.

RESULTS

Our model-based findings suggest that increasing testing rates alone will have minimal impact on reducing the expected number of infections compared to current conditions. However, in combination with increases in treatment coverage, this strategy could lead to a 59-68% reduction in the number of HIV infections over the next 5 years. Targeting men who are socially engaged with the gay community would result in the majority of potential reductions in incidence, with only minor improvements possible by reaching all other MSM.

CONCLUSIONS

Investing in strategies that will achieve higher coverage and earlier initiation of treatment to reduce infectiousness of HIV-infected individuals could be an effective strategy for reducing incidence in a population of MSM.

Mathematical models for the study of HIV spread and control amongst men who have sex with men

For a quarter of century, mathematical models have been used to study the spread and control of HIV amongst men who have sex with men (MSM). We searched MEDLINE and EMBASE databases up to the end of 2010 and reviewed this literature to summarise the methodologies used, key model developments, and the recommended strategies for HIV control amongst MSM. Of 742 studies identified, 127 studies met the inclusion criteria. Most studies employed deterministic modelling methods (80%). Over time we saw an increase in model complexity regarding antiretroviral therapy (ART), and a corresponding decrease in complexity regarding sexual behaviours. Formal estimation of model parameters was carried out in only a small proportion of the studies (22%) while model validation was considered by an even smaller proportion (17%), somewhat reducing confidence in the findings from the studies. Nonetheless, a number of common conclusions emerged, including (1) identification of the importance of assumptions regarding changes in infectivity and sexual contact rates on the impact of ART on HIV incidence, that subsequently led to empirical studies to gather these data, and (2) recommendation that multiple strategies would be required for effective HIV control amongst MSM. The role of mathematical models in studying epidemics is clear, and the lack of formal inference and validation highlights the need for further developments in this area. Improved methodologies for parameter estimation and systematic sensitivity analysis will help generate predictions that more fully express uncertainty, allowing better informed decision making in public health.

Effect of earlier initiation of antiretroviral treatment and increased treatment coverage on HIV-related mortality in China: a national observational cohort study

BACKGROUND

Overall HIV mortality rates in China have not been reported. In this analysis we assess overall mortality in treatment-eligible adults with HIV and attempt to identify risk factors for HIV-related mortality.

METHODS

We used data from the national HIV epidemiology and treatment databases to identify individuals aged 15 years or older with HIV who were eligible for highly active antiretroviral therapy between 1985 and 2009. Mortality rates were calculated in terms of person-years, with risk factors determined by Cox proportional hazard regression. Treatment coverage was calculated as the proportion of time that patients who were eligible for treatment received treatment, with risk factors for not receiving treatment identified by use of logistic regression.

FINDINGS

Of 323,252 people reported as having HIV in China by the end of 2009, 145,484 (45%) were identified as treatment-eligible and included in this analysis. Median CD4 count was 201 cells per μL (IQR 71-315) at HIV diagnosis and 194 cells per μL (73-293) when first declared eligible for treatment. Overall mortality decreased from 39·3 per 100 person-years in 2002 to 14·2 per 100 person-years in 2009, with treatment coverage concomitantly increasing from almost zero to 63·4%. By 2009, mortality was higher and treatment coverage lower in injecting drug users (15·9 deaths per 100 person-years; 42·7% coverage) and those infected sexually (17·5 deaths per 100 person-years; 61·7% coverage), compared with those infected through plasma donation or blood transfusion (6·7 deaths per 100 person-years; 80·2% coverage). The two strongest risk factors for HIV-related mortality were not receiving highly active antiretroviral therapy (adjusted hazard ratio 4·35, 95% CI 4·10-4·62) and having a CD4 count of less than 50 cells per μL when first declared eligible for treatment (7·92, 7·33-8.57).

INTERPRETATION

An urgent need exists for earlier HIV diagnosis and better access to treatment for injecting drug users and patients infected with HIV sexually, especially before they become severely immunosuppressed.

FUNDING

The National Centre for AIDS/STD Control and Prevention of the Chinese Centre for Disease Control and Prevention.

Modelling the impact of antiretroviral therapy on the epidemic of HIV

Thirty years after HIV first appeared it has killed close to 30 million people but transmission continues unchecked. In 2009, an estimated 1.8 million lives were lost and 2.6 million more people were infected with HIV [1]. To cut transmission, many social, behavioural and biomedical interventions have been developed, tested and tried but have had little impact on the epidemic in most countries. One substantial success has been the development of combination antiretroviral therapy (ART) that reduces viral load and restores immune function. This raises the possibility of using ART not only to treat people but also to prevent new HIV infections. Here we consider the impact of ART on the transmission of HIV and show how it could help to control the epidemic. Much needs to be known and understood concerning the impact of early treatment with ART on the prognosis for individual patients and on transmission. We review the current literature on factors associated with modelling treatment for prevention and illustrate the potential impact using existing models. We focus on generalized epidemics in sub- Saharan Africa, with an emphasis on South Africa, where transmission is mainly heterosexual and which account for an estimated 17% of all people living with HIV. We also make reference to epidemics among men who have sex with men and injection drug users where appropriate. We discuss ways in which using treatment as prevention can be taken forward knowing that this can only be the beginning of what must become an inclusive dialogue among all of those concerned to stop acquired immune deficiency syndrome (AIDS).

Antiretroviral therapy in prevention of HIV and TB: update on current research efforts

There is considerable scientific evidence supporting the use of antiretroviral therapy (ART) in prevention of human immunodeficiency virus (HIV) and tuberculosis (TB) infections. The complex nature of the HIV and TB prevention responses, resource constraints, remaining questions about cost and feasibility, and the need to use a solid evidence base to make policy decisions, and the implementation challenges to translating trial data to operational settings require a well-organised and coordinated response to research in this area. To this end, we aimed to catalogue the ongoing and planned research activities that evaluate the impact of ART plus other interventions on HIV- and/or TB-related morbidity, mortality, risk behaviour, HIV incidence and transmission. Using a limited search methodology, 50 projects were identified examining ART as prevention, representing 5 regions and 52 countries with a global distribution. There are 24 randomised controlled clinical trials with at least 12 large randomised individual or community cluster trials in resource-constrained settings that are in the planning or early implementation stages. There is considerable heterogeneity between studies in terms of methodology, interventions and geographical location. While the identified studies will undoubtedly advance our understanding of the efficacy and effectiveness of ART for prevention, some key questions may remain unanswered or only partially answered. The large number and wide variety of research projects emphasise the importance of this research issue and clearly demonstrate the potential for synergies, partnerships and coordination across funding agencies.

HIV treatment adherence, drug resistance, virologic failure: evolving concepts

Poor adherence to combined antiretroviral therapy (cART) has been shown to be a major determinant of virologic failure, emergence of drug resistant virus, disease progression, hospitalizations, mortality, and health care costs. While high adherence levels can be achieved in both resource-rich and resource-limited settings following initiation of cART, long-term adherence remains a challenge regardless of available resources. Barriers to optimal adherence may originate from individual (biological, socio-cultural, behavioral), pharmacological, and societal factors. Although patients and providers should continuously strive for maximum adherence to cART, there is accumulating evidence that each class of antiretroviral therapy has specific adherence-drug resistance relationship characteristics allowing certain regimens more flexibility than others. There is not a universally accepted measure for cART adherence, since each method has distinct advantages and disadvantages including cost, complexity, accuracy, precision, intrusiveness and bias. Development of a real-time cART adherence monitoring tool will enable the development of novel, pre-emptive adherence-improving strategies. The application of these strategies may ultimately prove to be the most cost-effective method to reduce morbidity and mortality for the individual and decrease the likelihood of HIV transmission and emergence of resistance in the community.

Antiretroviral therapy: a key component of a comprehensive HIV prevention strategy

Transmission of HIV is critically dependent on the level of HIV viral load within blood and genital secretions. Antiretroviral therapy results in sustained reductions in viral load to undetectable levels. Thus, antiretroviral therapy has long been postulated as a potential means to curb HIV transmission. Observational data have now confirmed that antiretroviral therapy is associated with a decrease in transmission among heterosexual serodiscordant couples, injection-drug users, and in population-based studies. Mathematical models suggest that further expansion of antiretroviral coverage within current guidelines can play a major role in controlling the spread of HIV. Concerns regarding the potential for transmission during acute HIV infection, behavioral disinhibition, and resistance to overcome the impact of treatment on prevention have not materialized to date. The Joint United Nations AIDS (UNAIDS) program has called for the inclusion of antiretroviral treatment as a key pillar in the global strategy to control the spread of HIV infection.

The spectrum of engagement in HIV care and its relevance to test-and-treat strategies for prevention of HIV infection

For individuals with human immunodeficiency virus (HIV) infection to fully benefit from potent combination antiretroviral therapy, they need to know that they are HIV infected, be engaged in regular HIV care, and receive and adhere to effective antiretroviral therapy. Test-and-treat strategies for HIV prevention posit that expanded testing and earlier treatment of HIV infection could markedly decrease ongoing HIV transmission, stemming the HIV epidemic. However, poor engagement in care for HIV-infected individuals will substantially limit the effectiveness of test-and-treat strategies. We review the spectrum of engagement in care for HIV-infected individuals in the United States and apply this information to help understand the magnitude of the challenges that poor engagement in care will pose to test-and-treat strategies for HIV prevention.

HIV treatment for prevention

"No virus, no transmission." Studies have repeatedly shown that viral load (the quantity of virus present in blood and sexual secretions) is the strongest predictor of HIV transmission during unprotected sex or transmission from infected mother to child.

Effective treatment lowers viral load to undetectable levels. If one could identify and treat all HIV-infected people immediately after infection, the HIV/AIDS epidemic would eventually disappear.

Such a radical solution is currently unrealistic. In reality, not all people get tested, especially when they fear stigma and discrimination. Thus, not all HIV-infected individuals are known. Of those HIV-positive individuals for whom the diagnosis is known, not all of them have access to therapy, agree to be treated, or are taking therapy effectively. Some on effective treatment will stop, and in others, the development of resistance will lead to treatment failure. Furthermore, resources are limited: should we provide drugs to asymptomatic HIV-infected individuals without indication for treatment according to guidelines in order to prevent HIV transmission at the risk of diverting funding from sick patients in urgent need?

In fact, the preventive potential of anti-HIV drugs is unknown. Modellers have tried to fill the gap, but models differ depending on assumptions that are strongly debated. Further, indications for antiretroviral treatments expand; in places like Vancouver and San Francisco, the majority of HIV-positive individuals are now under treatment, and the incidence of new HIV infections has recently fallen. However, correlation does not necessarily imply causation. Finally, studies in couples where one partner is HIV-infected also appear to show that treatment reduces the risk of transmission.

More definite studies, where a number of communities are randomized to either receive the "test-and-treat" approach or continue as before, are now in evaluation by funding agencies. Repeated waves of testing would precisely measure the incidence of HIV infection. Such trials face formidable logistical, practical and ethical obstacles. However, without definitive data, the intuitive appeal of "test-and-treat" is unlikely to translate into action on a global scale. In the meantime, based on the available evidence, we must strive to provide treatment to all those in medical need under the current medical guidelines. This will lead to a decrease in HIV transmission while "test-and-treat" is fully explored in prospective clinical trials.

Prevalence of sexually transmitted co-infections in people living with HIV/AIDS: systematic review with implications for using HIV treatments for prevention

Sexually transmitted co-infections increase HIV infectiousness through local inflammatory processes. The prevalence of STI among people living with HIV/AIDS has implications for containing the spread of HIV in general and the effectiveness of HIV treatments for prevention in particular. Here we report a systematic review of STI co-infections in people living with HIV/AIDS. We focus on STI contracted after becoming HIV infected. Electronic database and manual searches located 37 clinical and epidemiological studies of STI that increase HIV infectiousness. Studies of adults living with HIV/AIDS from developed and developing countries reported STI rates for 46 different samples (33 samples had clinical/laboratory confirmed STI). The overall mean point-prevalence for confirmed STI was 16.3% (SD=16.4), and median 12.4% STI prevalence in people living with HIV/AIDS. The most common STI studied were Syphilis with median 9.5% prevalence, Gonorrhea 9.5%, Chlamydia 5%, and Trichamoniasis 18.8% prevalence. STI prevalence was greatest at the time of HIV diagnosis, reflecting the role of STI in HIV transmission. Prevalence of STI among individuals receiving HIV treatment was not appreciably different from untreated persons. The prevalence of STI in people infected with HIV suggests that STI co-infections could undermine efforts to use HIV treatments for prevention by increasing genital secretion infectiousness.

Association of highly active antiretroviral therapy coverage, population viral load, and yearly new HIV diagnoses in British Columbia, Canada: a population-based study

BACKGROUND

Results of cohort studies and mathematical models have suggested that increased coverage with highly active antiretroviral therapy (HAART) could reduce HIV transmission. We aimed to estimate the association between plasma HIV-1 viral load, HAART coverage, and number of new cases of HIV in the population of a Canadian province.

METHODS

We undertook a population-based study of HAART coverage and HIV transmission in British Columbia, Canada. Data for number of HIV tests done and new HIV diagnoses were obtained from the British Columbia Centre for Disease Control. Data for viral load, CD4 cell count, and HAART use were extracted from the British Columbia Centre for Excellence in HIV/AIDS population-based registries. We modelled trends of new HIV-positive tests and number of individuals on HAART using generalised additive models. Poisson log-linear regression models were used to estimate the association between new HIV diagnoses and viral load, year, and number of individuals on HAART.

FINDINGS

Between 1996 and 2009, the number of individuals actively receiving HAART increased from 837 to 5413 (547% increase; p=0.002), and the number of new HIV diagnoses fell from 702 to 338 per year (52% decrease; p=0.001). The overall correlation between number of individuals on HAART and number of individuals newly testing positive for HIV per year was -0.89 (p<0.0001). For every 100 additional individuals on HAART, the number of new HIV cases decreased by a factor of 0.97 (95% CI 0.96-0.98), and per 1 log(10) decrease in viral load, the number of new HIV cases decreased by a factor of 0.86 (0.75-0.98).

INTERPRETATION

We have shown a strong population-level association between increasing HAART coverage, decreased viral load, and decreased number of new HIV diagnoses per year. Our results support the proposed secondary benefit of HAART used within existing medical guidelines to reduce HIV transmission.

FUNDING

Ministry of Health Services and Ministry of Healthy Living and Sport, Province of British Columbia; US National Institute on Drug Abuse; US National Institutes of Health; Canadian Institutes of Health Research.