Comparative effectiveness of HIV testing and treatment in highly endemic regions

Socioeconomic inequality in adults undertaking HIV testing over time in Ethiopia based on data from demographic and health surveys

INTRODUCTION

HIV testing is the entry point to HIV prevention, care and treatment and needs continuous evaluation to understand whether all social groups have accessed services equally. Addressing disparities in HIV testing between social groups results in effective and efficient response against HIV prevention. Despite these benefits, there was no previous study on inequality and determinants over time in Ethiopia. Thus, the objective of this research was to examine socioeconomic inequality in individuals undertaking HIV testing over time, allowing for the identification of persistent and emerging determinants.

METHODS

Data sources for the current study were the 2011 and 2016 Ethiopian Demographic Health Surveys. The 2016 population health survey is the one that Ethiopia used to set national AIDS response strategies; there was no other recent survey with HIV/AIDS-related indicators in Ethiopia. The final sample size for the current study was 28,478 for the year 2011 and 25,542 for the year 2016. The concentration curve and Erreygers' concentration index were used to estimate socioeconomic inequality in HIV testing. Subsequently, decomposition analysis was performed to identify persistent and emerging contributors of socioeconomic inequality. Generalized linear regression model with the logit link function was employed to estimate the marginal effect, elasticity, Erreygers' concentration index (ECI), and absolute and percentage contributions of each covariate.

RESULTS

The concentration curve was below the line of equality over time, revealing the pro-rich inequality in HIV testing. The inequality was observed in both 2011 (ECI = 0.200) and 2016 (ECI = 0.213). A household wealth rank had the highest percentage contribution (49.2%) for inequality in HIV testing in 2011, which increased to 61.1% in 2016. Additional markers include listening to the radio (13.4% in 2011 and 12.1% in 2016), education status (8.1% in 2011 and 6.8% in 2016), and resident (-2.0% in 2011 and 6.3% in 2016). Persistent determinants of individuals undertaking HIV testing were age 20-34 years, geographic region, education status, marital status, religion, income, media exposure (listening to the radio, reading newspaper, watching television), knowledge about HIV/AIDS, and attitudes towards people living with HIV. Age between 35 and 44 years and urban residence emerged as new associated factors in 2016.

CONCLUSIONS

The higher HIV testing coverage was among individuals with higher socioeconomic status in Ethiopia. Socioeconomic inequality amongst individuals undertaking HIV testing was diverging over time. Household wealth rank, mass media exposure, education status, and resident took the largest share in explaining the disparity in individuals undertaking HIV testing between the lower and higher income groups. Therefore, interventions to equalise HIV testing coverage should take account of these determinants.

Improving access to health services through health reform in Lesotho: Progress made towards achieving Universal Health Coverage

In 2014 the Kingdom of Lesotho, in conjunction with Partners In Health, launched a National Health Reform with three components: 1) improved supply-side inputs based on disease burden in the catchment area of each of 70 public primary care clinics, 2) decentralization of health managerial capacity to the district level, and 3) demand-side interventions including paid village health workers. We assessed changes in the quarterly average of quality metrics from pre-National Health Reform in 2013 to 2017, which included number of women attending their first antenatal care visit, number of post-natal care visits attended, number of children fully immunized at one year of age, number of HIV tests performed, number of HIV infection cases diagnosed, and the availability of essential health commodities. The number of health centers adequately equipped to provide a facility-based delivery increased from 3% to 95% with an associated increase in facility-based deliveries from 2% to 33%. The number of women attending their first antenatal and postnatal care visits rose from 1,877 to 2,729, and 1,908 to 2,241, respectively. The number of children fully immunized at one year of life increased from 191 to 294. The number of HIV tests performed increased from 5,163 to 12,210, with the proportion of patients living with HIV lost to follow-up falling from 27% to 22%. By the end of the observation period, the availability of essential health commodities increased to 90% or above. Four years after implementation of the National Health Reform, we observed increases in antenatal and post-natal care, and facility-based deliveries, as well as child immunization, and HIV testing and retention in care. Improved access to and utilization of primary care services are important steps toward improving health outcomes, but additional longitudinal follow-up of the reform districts will be needed.

The Impact of Universal Test and Treat Program on Highly Active Anti Retroviral Therapy Outcomes (Coverage, Adherence and Lost to Follow Up) at Wangaya Hospital in Denpasar, Bali-Indonesia: A Retrospective Cohort Study

Background:

World Health Organization (WHO) (2015) recommended that all people diagnosed with human immunodeficiency virus (HIV)-positive initiate Highly Active Anti Retroviral Therapy (HAART) immediately (less than a week), irrespective of CD4 count (Universal Test and Treat / UTT) Program.

Objective:

To evaluate the impact of UTT as a current therapeutic program on HIV treatment outcomes, coverage, adherence, and lost to follow-up (LTFU) at Wangaya Hospital in Denpasar, Bali, Indonesia.

Methods:

A Retrospective cohort study was conducted during July 2017 - June 2018 (Pre-UTT) and September 2018 – August 2019 (Post-UTT). Around 402 medical records were selected, reviewed, and enrolled. Data were analyzed using SPSS software for windows version 24.0. Bivariate analysis (Chi-square test) was performed on all variables with a statistically significant t level of 0.05.

Results:

Among 4,322 new visitors; 3,585 (82.95%) agreed to take HIV test and 402(11.21%) were confirmed HIV reactive. Most participants confirmed HIV reactive occured at age 25-34 years old and 230 (57.21%) were male. The majority education level were primary (Junior high school) 302(75.12%), 379(94.28%) were employed and 281 (69.90%) stayed in Denpasar. About 350 (87.06%) received HAART, 298 (85.14%) with high adherence and 52 (14.86%) LTFU. Pre-UTT, HAART coverage; 83.03% (181), were statistically significant increased to 91.85% (169) post UTT (p=0.000). High adherence pre-UTT; 79.56% (144) was significantly increased to 91.12% (154) post UTT (p=0.006) and LTFU were significantly decreased; 20.44% (37) to 8.87% (15) (p=0.006).

Conclusion:

UTT program significantly improve the HIV treatment outcome (increased coverage, adherence, and decreased LTFU).

Effect of the Test and Treat Strategy on Mortality Among HIV-Positive Adult Clients on Antiretroviral Treatment in Public Hospitals of Addis Ababa, Ethiopia

Background

The primary goal of antiretroviral therapy is to prevent human immune deficiency virus (HIV)-related morbidity and mortality. Deferring antiretroviral therapy (ART) until CD4 counts decline puts individuals with HIV at risk of HIV-related morbidity and mortality.

Objective

This study aims to assess the effect of the test and treat strategy on mortality among HIV-positive clients on ART in public hospitals in Addis Ababa.

Methods

A retrospective cohort study was conducted at five selected public hospitals in Addis Ababa. A cohort of 216 ART clients taken as an exposed group (test and treat" strategy) from 2017 to 2019 and 216 ART clients as an unexposed group taken from 2014 to 2017; totally, 432 clients were included in the study. Multivariate Cox regression was used to estimate the effect of the test and treat strategy on the survival of ART clients adjusting for other covariates.

Results

The 432 clients contributed to a total of 1025.17 person-years follow-up. Ninety-one (21.06%) of them died, 14.3% were unexposed and 6.7% were exposed (test and treat). The incidence of death was 92.4 and 81.8/1000 person-years in the unexposed group and exposed group, respectively, with an overall mortality rate of 88.8/1000 person-years. Besides, test and treat strategy (AHR: 0.31; 95% CI: 0.19, 0.52), baseline CD4 counts >350 cells/mm3 (AHR 0.40; 95%: CI: 0.20, 0.80), bedridden functional status (AHR 2.46; 95% CI: 1.41, 4.27), poor adherence (AHR 3.25; 95% CI: 1.410-7.51), moderate malnutrition on last visit (AHR 2.56; 95% CI: 1.30-5.04) and staying on original regimen (AHR 4.68; 95% CI 2.72, 8.07) were independent predictors of mortality.

Conclusion

Mortality among HIV patients on treatment decreased significantly since the start of the test and treat strategy. Therefore, test and treat strategy should be strengthened in all public and private facilities throughout the country.

Health outcomes and cost-effectiveness of diversion programs for low-level drug offenders: A model-based analysis

BACKGROUND

Cycles of incarceration, drug abuse, and poverty undermine ongoing public health efforts to reduce overdose deaths and the spread of infectious disease in vulnerable populations. Jail diversion programs aim to divert low-level drug offenders toward community care resources, avoiding criminal justice costs and disruptions in treatment for HIV, hepatitis C virus (HCV), and drug abuse. We sought to assess the health benefits and cost-effectiveness of a jail diversion program for low-level drug offenders.

METHODS AND FINDINGS

We developed a microsimulation model, calibrated to King County, Washington, that captured the spread of HIV and HCV infections and incarceration and treatment systems as well as preexisting interventions such as needle and syringe programs and opiate agonist therapy. We considered an adult population of people who inject drugs (PWID), people who use drugs but do not inject (PWUD), men who have sex with men, and lower-risk heterosexuals. We projected discounted lifetime costs and quality-adjusted life years (QALYs) over a 10-year time horizon with and without a jail diversion program and calculated resulting incremental cost-effectiveness ratios (ICERs) from the health system and societal perspectives. We also tracked HIV and HCV infections, overdose deaths, and jail population size. Over 10 years, the program was estimated to reduce HIV and HCV incidence by 3.4% (95% CI 2.7%-4.0%) and 3.3% (95% CI 3.1%-3.4%), respectively, overdose deaths among PWID by 10.0% (95% CI 9.8%-10.8%), and jail population size by 6.3% (95% CI 5.9%-6.7%). When considering healthcare costs only, the program cost $25,500/QALY gained (95% CI $12,600-$48,600). Including savings from reduced incarceration (societal perspective) improved the ICER to $6,200/QALY gained (95% CI, cost-saving $24,300). Sensitivity analysis indicated that cost-effectiveness depends on diversion program participants accessing community programs such as needle and syringe programs, treatment for substance use disorder, and HIV and HCV treatment, as well as diversion program cost. A limitation of the analysis is data availability, as fewer data are available for diversion programs than for more established interventions aimed at people with substance use disorder. Additionally, like any model of a complex system, our model relies on simplifying assumptions: For example, we simplified pathways in the healthcare and criminal justice systems, modeled an average efficacy for substance use disorder treatment, and did not include costs associated with homelessness, unemployment, and breakdown in family structure.

CONCLUSIONS

We found that diversion programs for low-level drug offenders are likely to be cost-effective, generating savings in the criminal justice system while only moderately increasing healthcare costs. Such programs can reduce incarceration and its associated costs, and also avert overdose deaths and improve quality of life for PWID, PWUD, and the broader population (through reduced HIV and HCV transmission).

The differential impacts of non-locally acquired infections and treatment interventions on heterosexual HIV transmission in Hong Kong

Introduction

Heterosexual infections have contributed to a high proportion of the HIV burden in Asia and Eastern Europe. Human mobility and non-local infections are important features in some cities/countries. An understanding of the determinants of the sustained growth of the heterosexual HIV epidemics would enable the potential impacts of treatment-based interventions to be assessed.

Methods

We developed a compartmental model for heterosexual HIV transmissions, parameterized by clinical and surveillance data (1984–2014) in Hong Kong. HIV sequence data were included for examining genetic linkages and clustering pattern. We performed sensitivity analyses to evaluate effects of high-risk sexual partnership and proportions of non-locally acquired infections. Four hypothetical interventions (a) immediate treatment, (b) enhancement of retention in care, (c) HIV testing campaigns, and (d) test-and-treat strategy, were examined.

Results

Data of 2174 patients (723 female and 1451 male) diagnosed with HIV between 1984 and 2012 in Hong Kong were collected for model parameterization. Among 1229 sequences of non-MSM (men who have sex with men) patients, 70% were isolates and 17% were either dyads or triads. In base-case scenario, the total estimated number of new infections in 2012–2023 would be 672 for male and 452 for female. Following 100% retention in care intervention, the total proportion of averted new infections in 2012–2023 would be 7% for male and 10% for female. HIV testing campaign in 2012 and 2017 followed by 100% immediate treatment strategy would avert 5% and 9% of male and female new infections, respectively. In the epidemic model, an increase of high-risk sexual partnership from 6% to 9% would increase the epidemic growth (annual number of newly diagnosed and newly infected cases) by about 10%. If no non-locally acquired infection occurred as from 2012, the epidemic growth would slump. To control the heterosexual epidemic, periodic HIV testing at 5-year intervals with immediate treatment would avert 5–13% of annual new infections in 2013–2023.

Conclusions

Enhanced HIV testing with immediate treatment is most effective in controlling the heterosexual epidemic, the impacts of which might however be attenuated by any increase of non-locally acquired infection, assuming little variations of high risk partnership over time.

The effect of "universal test and treat" program on HIV treatment outcomes and patient survival among a cohort of adults taking antiretroviral treatment (ART) in low income settings of Gurage zone, South Ethiopia

BACKGROUND

Through universal "test and treat approach" (UTT) it is believed that HIV new infection and AIDS related death will be reduced at community level and through time HIV can be eliminated. With this assumption the UTT program was implemented since 2016. However, the effect of this program in terms of individual patient survival and treatment outcome was not assessed in relation to the pre-existing defer treatment approach.

OBJECTIVE

To assess the effects of UTT program on HIV treatment outcomes and patient survival among a cohort of adult HIV infected patients taking antiretroviral treatment in Gurage zone health facilities.

METHODS

Institution based retrospective cohort study was conducted in facilities providing HIV care and treatment. Eight years (2012-2019) HIV/AIDS treatment records were included in the study. Five hundred HIV/AIDS treatment records were randomly selected and reviewed. Data were abstracted using standardized checklist by trained health professionals; then it was cleaned, edited and entered by Epi info version 7 and analyzed by STATA. Cox model was built to estimate survival differences across different study variables.

RESULTS

A total of 500 patients were followed for 1632.6 person-year (PY) of observation. The overall incidence density rate (IDR) of death in the cohort was 3 per-100-PY. It was significantly higher for differed treatment program, which is 3.8 per-100-PY compared to 2.4 per-100-PY in UTT program with a p value of 0.001. The relative risk of death among differed cases was 1.58 times higher than the UTT cases. The cumulative probability of survival at the end of 1st, 2nd, 3rd, and 4th years was 98%, 90.2%, 89.2% and 88% respectively with difference between groups. The log rank test and Kaplan-Meier survival curve indicated patients enrolled in the UTT program survived longer than patients enrolled in the differed treatment program (log rank X2 test = 4.1, p value = 0.04). Age, residence, base line CD4 count, program of enrolment, development of new OIS and treatment failure were predicted mortality from HIV infection.

CONCLUSION

Mortality was significantly reduced after UTT. Therefore, intervention to further reduce deaths has to focus on early initiation of treatment and strengthening UTT programs.

Cost-effectiveness analysis of pre-ART HIV drug resistance testing in Kenyan women

BACKGROUND

The prevalence of pre-treatment drug resistance (PDR) to non-nucleoside reverse-transcriptase inhibitor (NNRTI) agents is increasing in sub-Saharan Africa, which may decrease the effectiveness of efavirenz-based antiretroviral therapy (ART) programs. However, due to recent safety concerns, there has been hesitancy to replace efavirenz-based ART with dolutegravir in women of reproductive potential. Our objective was to evaluate whether PDR testing for women not initiating dolutegravir-based ART would be a cost-effective strategy to address the challenges posed by PDR.

METHODS

We developed an HIV drug resistance model that simulates the emergence and transmission of resistance mutations, calibrated to the Kenyan epidemic. We modeled three care strategies for PDR testing among women not initiating dolutegravir-based ART: no PDR testing, PDR testing with a low-cost point mutation assay, known as oligonucleotide ligation assay (OLA), and PDR testing with consensus sequencing. Using a health sector perspective, this model was used to evaluate the health outcomes, lifetime costs, and cost-effectiveness under each strategy over a 15-year time horizon starting in 2019.

FINDINGS

OLA and CS PDR testing were projected to have incremental cost-effectiveness ratios (ICER) of $10,741/QALY gained and $134,396/QALY gained, respectively, which are not cost-effective by national income standards. Viral suppression rates among women at 12 months after ART initiation were 87·8%, 89·0%, and 89·3% with no testing, OLA testing, and CS testing, respectively. PDR testing with OLA and CS were associated with a 0.5% and 0.6% reduction in incidence rate compared to no PDR testing. Initial PDR prevalence among women was 13.1% in 2019. By 2034, this prevalence was 17·6%, 17·4%, and 17·3% with no testing, OLA testing, and CS testing, respectively.

INTERPRETATION

PDR testing for women is unlikely to be cost-effective in Kenya whether one uses a low-cost assay, such as OLA, or consensus sequencing.

FUNDING

National Institutes of Health, Gilead Sciences.

Structural Design and Data Requirements for Simulation Modelling in HIV/AIDS: A Narrative Review

Born out of a necessity for fiscal sustainability, simulation modeling is playing an increasingly prominent role in setting priorities for combination implementation strategies for HIV treatment and prevention globally. The design of a model and the data inputted into it are central factors in ensuring credible inferences. We executed a narrative review of a set of dynamic HIV transmission models to comprehensively synthesize and compare the structural design and the quality of evidence used to support each model. We included 19 models representing both generalized and concentrated epidemics, classified as compartmental, agent-based, individual-based microsimulation or hybrid in our review. We focused on four structural components (population construction; model entry, exit and HIV care engagement; HIV disease progression; and the force of HIV infection), and two analytical components (model calibration/validation; and health economic evaluation, including uncertainty analysis). While the models we reviewed focused on a variety of individual interventions and their combinations, their structural designs were relatively homogenous across three of the four focal components, with key structural elements influenced by model type and epidemiological context. In contrast, model entry, exit and HIV care engagement tended to differ most across models, with some health system interactions-particularly HIV testing-not modeled explicitly in many contexts. The quality of data used in the models and the transparency with which the data was presented differed substantially across model components. Representative and high-quality data on health service delivery were most commonly not accessed or were unavailable. The structure of an HIV model should ideally fit its epidemiological context and be able to capture all efficacious treatment and prevention services relevant to a robust combination implementation strategy. Developing standardized guidelines on evidence syntheses for health economic evaluation would improve transparency and help prioritize data collection to reduce decision uncertainty.

Estimated Impact of Targeted Pre-Exposure Prophylaxis: Strategies for Men Who Have Sex with Men in the United States

Pre-exposure prophylaxis (PrEP) effectively reduces human immunodeficiency virus (HIV) transmission. We aimed to estimate the impact of different PrEP prioritization strategies among Black and Latino men who have sex with men (MSM) in the United States, populations most disproportionately affected by HIV. We developed an agent-based simulation to model the HIV epidemic among MSM. Individuals were assigned an HIV incidence risk index (HIRI-MSM) based on their sexual behavior. Prioritization strategies included PrEP use for individuals with HIRI-MSM ≥10 among all MSM, all Black MSM, young (≤25 years) Black MSM, Latino MSM, and young Latino MSM. We estimated the number needed to treat (NNT) to prevent one HIV infection, reductions in prevalence and incidence, and subsequent infections in non-PrEP users avoided under these strategies over 5 years (2016-2020). Young Black MSM eligible for PrEP had the lowest NNT (NNT = 10) followed by all Black MSM (NNT = 33) and young Latino MSM (NNT = 35). All Latino MSM and all MSM had NNT values of 63 and 70, respectively. Secondary infection reduction with PrEP was the highest among young Latino MSM (53.2%) followed by young Black MSM (37.8%). Targeting all MSM had the greatest reduction in prevalence (14.7% versus 2.9%-3.9% in other strategies) and incidence (49.4% versus 9.4%-13.9% in other groups). Using data representative of the United States MSM population, we found that a strategy of universal PrEP use by MSM was most effective in reducing HIV prevalence and incidence of MSM. Targeted use of PrEP by Black and Latino MSM, however, especially those ≤25 years, had the greatest impact on HIV prevention.

Test and Treat TB: a pilot trial of GeneXpert MTB/RIF screening on a mobile HIV testing unit in South Africa

BACKGROUND

Community-based GeneXpert MTB/RIF testing may increase detection of prevalent TB in the community and improve rates of TB treatment completion.

METHODS

We conducted a pilot randomized trial to evaluate the impact of GeneXpert screening on a mobile HIV testing unit. Adults (≥18y) underwent rapid HIV testing and TB symptom screening and were randomized to usual mobile unit care (providing sputum on the mobile unit sent out for GeneXpert testing) or the "Test & Treat TB" intervention with immediate GeneXpert testing. Symptomatic participants in usual care produced sputum that was sent for hospital-based GeneXpert testing; participants were contacted ~ 7 days later with results. In the "Test & Treat TB" intervention, HIV-infected or HIV-uninfected/TB symptomatic participants underwent GeneXpert testing on the mobile unit. GeneXpert+ participants received expedited TB treatment initiation, monthly SMS reminders and non-cash incentives. We assessed 6-month TB treatment outcomes.

RESULTS

4815 were eligible and enrolled; median age was 27 years (IQR 22 to 35). TB symptoms included cough (5%), weight loss (4%), night sweats (4%), and fever (3%). 42% of eligible participants produced sputum (intervention: 56%; usual care: 26%). Seven participants tested GeneXpert+, six in the intervention (3%, 95% CI 1%, 5%) and one in usual care (1%, 95% CI 0%, 6%). 5 of 6 intervention participants completed TB treatment; the GeneXpert+ participant in usual care did not.

CONCLUSION

GeneXpert MTB/RIF screening on a mobile HIV testing unit is feasible. Yield for GeneXpert+ TB was low, however, the "Test & Treat TB" strategy led to high rates of TB treatment completion.

TRIAL REGISTRATION

This study was registered on November 21, 2014 at ClinicalTrials.gov ( NCT02298309 ).

Mathematical modelling to inform 'treat all' implementation in sub-Saharan Africa: a scoping review

OBJECTIVE

Despite widespread uptake, only half of sub-Saharan African countries have fully implemented the World Health Organization's 'treat all' policy, hindering achievement of global HIV targets. We examined literature on mathematical modelling studies that sought to inform scale-up and implementation of 'treat all' in sub-Saharan Africa.

METHODS

We conducted a scoping review, a research synthesis to assess emerging evidence and identify gaps, of peer-reviewed literature, extracting study characteristics on 'treat all' policies and assumptions, setting, key populations, outcomes and findings. Studies were narratively summarised and potential gaps characterised.

RESULTS

We identified 16 studies examining 'treat all' alone (n=12) or with expanded testing (n=7) and/or care continuum improvements (n=6). Twelve studies examined 'treat all' for Southern African countries, while none did so for Central Africa. Four included the role of resistance; one evaluated any key population. A range of health and economic outcomes were reported, although fewer studies formally assessed budget impact. Fourteen studies involved co-authors with any in-country affiliation; one study also had co-authors with local government affiliation. Overall, 'treat all' improves health outcomes and is cost-effective compared to deferred HIV treatment; 'treat all' with expanded testing or care continuum improvements may provide further health benefits. However, studies generally used optimistic assumptions about the implementation of expanded testing or care continuum improvements.

CONCLUSIONS

The modelling literature demonstrates improved health and economic benefits of 'treat all'. Using mathematical modelling to inform real-world implementation of 'treat all' requires realistic assumptions about expanded testing and care continuum interventions across a wide range of settings and populations.

Success factors for universal access to antiretroviral treatments in South Africa

This article studies the epidemiological and economic impacts of a universal testing and treatment policy of Human Immunodeficiency Virus (HIV) in South Africa. A model of disease transmission is built to simulate several implementation scenarios of the policy. Different behavioral responses in the general population are considered. The results show that the success of a large-scale HIV testing and treatment program in South Africa depends on its implementation conditions. The policy can lead to a reduction of the HIV epidemic, even in the case of a large relapse in preventive behaviors in the general population, if implementation conditions are favorable. This is the case if the number of infected individuals who are infectious is greatly reduced. From an economic point of view, taking into account the positive externality of antiretroviral (ARV) treatments changes the traditional framework of cost-benefit analyses. A large-scale testing and treatment program would be cost-saving in the case of favorable implementation conditions, even following a large increase in risk behaviors after the scaling up of ARV treatments. By contrast, the analysis stresses out the potential perverse effects of scaling up ARV treatments in South Africa if the intervention is set up without ensuring enough resources for patients' monitoring and the availability of effective ARV drugs. Indeed, if the number of treated patients rises while adherence of patients to treatments decreases and the rate of loss to follow-up increases, the policy could extend the pool of infectious patients and lead to a long-term amplification of the epidemic.

Treatment of HIV for the Prevention of Transmission in Discordant Couples and at the Population Level

The scientific breakthrough proving that antiretroviral therapy (ART) can halt heterosexual HIV transmission came in the form of a landmark clinical trial conducted among serodiscordant couples. Study findings immediately informed global recommendations for the use of treatment as prevention in serodiscordant couples. The extent to which these findings are generalizable to other key populations or to groups exposed to HIV through nonsexual transmission routes (i.e., anal intercourse or unsafe injection of drugs) has since driven a large body of research. This review explores the history of HIV research in serodiscordant couples, the implications for management of couples, subsequent research on treatment as prevention in other key populations, and challenges in community implementation of these strategies.

Structural Sensitivity in HIV Modeling: A Case Study of Vaccination

Structural assumptions in infectious disease models, such as the choice of network or compartmental model type or the inclusion of different types of heterogeneity across individuals, might affect model predictions as much as or more than the choice of input parameters. We explore the potential implications of structural assumptions on HIV model predictions and policy conclusions. We illustrate the value of inference robustness assessment through a case study of the effects of a hypothetical HIV vaccine in multiple population subgroups over eight related transmission models, which we sequentially modify to vary over two dimensions: parameter complexity (e.g., the inclusion of age and HCV comorbidity) and contact/simulation complexity (e.g., aggregated compartmental vs. individual/disaggregated compartmental vs. network models). We find that estimates of HIV incidence reductions from network models and individual compartmental models vary, but those differences are overwhelmed by the differences in HIV incidence between such models and the aggregated compartmental models (which aggregate groups of individuals into compartments). Complexities such as age structure appear to buffer the effects of aggregation and increase the threshold of net vaccine effectiveness at which aggregated models begin to overestimate reductions. The differences introduced by parameter complexity in estimated incidence reduction also translate into substantial differences in cost-effectiveness estimates. Parameter complexity does not appear to play a consistent role in differentiating the projections of network models.

Mortality along the continuum of HIV care in Rwanda: a model-based analysis

Background

HIV is the leading cause of death among adults in sub-Saharan Africa. However, mortality along the HIV care continuum is poorly described. We combine demographic, epidemiologic, and health services data to estimate where are people with HIV dying along Rwanda’s care continuum.

Methods

We calibrated an age-structured HIV disease and transmission stochastic simulation model to the epidemic in Rwanda. We estimate mortality among HIV-infected individuals in the following states: untested, tested without establishing care in an antiretroviral therapy (ART) program (unlinked), in care before initiating ART (pre-ART), lost to follow-up (LTFU) following ART initiation, and retained in active ART care. We estimated mortality among people living with HIV in Rwanda through 2025 under current conditions, and with improvements to the HIV care continuum.

Results

In 2014, the greatest portion of deaths occurred among those untested (35.4%), followed by those on ART (34.1%), reflecting the large increase in the population on ART. Deaths among those LTFU made up 11.8% of all deaths among HIV-infected individuals in 2014, and in the base case this portion increased to 18.8% in 2025, while the contribution to mortality declined among those untested, unlinked, and in pre-ART. In our model only combined improvements to multiple aspects of the HIV care continuum were projected to reduce the total number of deaths among those with HIV, estimated at 8177 in 2014, rising to 10,659 in the base case, and declining to 5,691 with combined improvements in 2025.

Conclusion

Mortality among those untested for HIV contributes a declining portion of deaths among HIV-infected individuals in Rwanda, but the portion of deaths among those LTFU is expected to increase the most over the next decade. Combined improvements to the HIV care continuum might be needed to reduce the number of deaths among those with HIV.

Electronic supplementary material

The online version of this article (doi:10.1186/s12879-016-2052-7) contains supplementary material, which is available to authorized users.

A Comparison of Two Mathematical Modeling Frameworks for Evaluating Sexually Transmitted Infection Epidemiology

BACKGROUND

Different models of sexually transmitted infections (STIs) can yield substantially different conclusions about STI epidemiology, and it is important to understand how and why models differ. Frequency-dependent models make the simplifying assumption that STI incidence is proportional to STI prevalence in the population, whereas network models calculate STI incidence more realistically by classifying individuals according to their partners' STI status.

METHODS

We assessed a deterministic frequency-dependent model approximation to a microsimulation network model of STIs in South Africa. Sexual behavior and demographic parameters were identical in the 2 models. Six STIs were simulated using each model: HIV, herpes, syphilis, gonorrhea, chlamydia, and trichomoniasis.

RESULTS

For all 6 STIs, the frequency-dependent model estimated a higher STI prevalence than the network model, with the difference between the 2 models being relatively large for the curable STIs. When the 2 models were fitted to the same STI prevalence data, the best-fitting parameters differed substantially between models, with the frequency-dependent model suggesting more immunity and lower transmission probabilities. The fitted frequency-dependent model estimated that the effects of a hypothetical elimination of concurrent partnerships and a reduction in commercial sex were both smaller than estimated by the fitted network model, whereas the latter model estimated a smaller impact of a reduction in unprotected sex in spousal relationships.

CONCLUSIONS

The frequency-dependent assumption is problematic when modeling short-term STIs. Frequency-dependent models tend to underestimate the importance of high-risk groups in sustaining STI epidemics, while overestimating the importance of long-term partnerships and low-risk groups.

Can the Heterosexual HIV Epidemic be Eliminated in South Africa Using Combination Prevention? A Modeling Analysis

Little is known about how combining efficacious interventions for human immunodeficiency virus (HIV) prevention could lead to HIV elimination. We used an agent-based simulation model, the HIV calibrated dynamic model, to assess the potential for HIV elimination in South Africa. We examined several scenarios (from continuation of the current status quo to perfect achievement of targets) with differing combinations of male condom use, adult male circumcision, HIV testing, and early antiretroviral therapy (ART). We varied numerous parameters, including the proportion of adult males circumcised, the frequency of condom use during sex acts, acceptance of HIV testing, linkage to health care, criteria for ART initiation, ART viral suppression rates, and loss to follow-up. Maintaining current levels of combination prevention would lead to increasing HIV incidence and prevalence in South Africa, while the perfect combination scenario was projected to eliminate HIV on a 50-year time scale from 2013 to 2063. Perfecting testing and treatment, without changing condom use or circumcision rates, resulted in an 89% reduction in HIV incidence but not elimination. Universal adult male circumcision alone resulted in a 21% incidence reduction within 20 years. Substantial decreases in HIV incidence are possible from sufficient uptake of both primary prevention and ART, but with continuation of the status quo, HIV elimination in South Africa is unlikely within a 50-year time scale.

Impact of early treatment programs on HIV epidemics: An immunity-based mathematical model

While studies on pre-exposure prophylaxis (PrEP) and post-exposure prophylaxis (PEP) have demonstrated substantial advantages in controlling HIV transmission, the overall benefits of the programs with early initiation of antiretroviral therapy (ART) have not been fully understood and are still on debate. Here, we develop an immunity-based (CD4+ T cell count based) mathematical model to study the impacts of early treatment programs on HIV epidemics and the overall community-level immunity. The model is parametrized using the HIV prevalence data from South Africa and fully analyzed for stability of equilibria and infection persistence criteria. Using our model, we evaluate the effects of early treatment on the new infection transmission, disease death, basic reproduction number, HIV prevalence, and the community-level immunity. Our model predicts that the programs with early treatments significantly reduce the new infection transmission and increase the community-level immunity, but the treatments alone may not be enough to eliminate HIV epidemics. These findings, including the community-level immunity, might provide helpful information for proper implementation of HIV treatment programs.

Attrition through multiple stages of pre-treatment and ART HIV care in South Africa

INTRODUCTION

While momentum for increasing treatment thresholds is growing, if patients cannot be retained in HIV care from the time of testing positive through long-term adherence to antiretroviral therapy (ART), such strategies may fall short of expected gains. While estimates of retention on ART exist, few cohorts have data on retention from testing positive through long-term ART care.

METHODS

We explored attrition (loss or death) at the Themba Lethu HIV clinic, Johannesburg, South Africa in 3 distinct cohorts enrolled at HIV testing, pre-ART initiation, and ART initiation.

RESULTS

Between March 2010 and August 2012 we enrolled 380 patients testing HIV+, 206 initiating pre-ART care, and 185 initiating ART. Of the 380 patients enrolled at testing HIV-positive, 38.7% (95%CI: 33.9-43.7%) returned for eligibility staging within ≤3 months of testing. Of the 206 enrolled at pre-ART care, 84.5% (95%CI: 79.0-88.9%) were ART eligible at their first CD4 count. Of those, 87.9% (95%CI: 82.4-92.2%) initiated ART within 6 months. Among patients not ART eligible at their first CD4 count, 50.0% (95%CI: 33.1-66.9%) repeated their CD4 count within one year of the first ineligible CD4. Among the 185 patients in the ART cohort, 22 transferred out and were excluded from further analysis. Of the remaining 163, 81.0% (95%CI: 74.4-86.5%) were retained in care through two years on treatment.

CONCLUSIONS

Our findings from a well-resourced clinic demonstrate continual loss from all stages of HIV care and strategies to reduce attrition from all stages of care are urgently needed.

Interventions to improve or facilitate linkage to or retention in pre-ART (HIV) care and initiation of ART in low- and middle-income settings--a systematic review

INTRODUCTION

Several approaches have been taken to reduce pre-antiretroviral therapy (ART) losses between HIV testing and ART initiation in low- and middle-income countries, but a systematic assessment of the evidence has not yet been undertaken. The aim of this systematic review is to assess the potential for interventions to improve or facilitate linkage to or retention in pre-ART care and initiation of ART in low- and middle-income settings.

METHODS

An electronic search was conducted on Medline, Embase, Global Health, Web of Science and conference databases to identify studies describing interventions aimed at improving linkage to or retention in pre-ART care or initiation of ART. Additional searches were conducted to identify on-going trials on this topic, and experts in the field were contacted. An assessment of the risk of bias was conducted. Interventions were categorized according to key domains in the existing literature.

RESULTS

A total of 11,129 potentially relevant citations were identified, of which 24 were eligible for inclusion, with the majority (n=21) from sub-Saharan Africa. In addition, 15 on-going trials were identified. The most common interventions described under key domains included: health system interventions (i.e. integration in the setting of antenatal care); patient convenience and accessibility (i.e. point-of-care CD4 count (POC) testing with immediate results, home-based ART initiation); behaviour interventions and peer support (i.e. improved communication, patient referral and education) and incentives (i.e. food support). Several interventions showed favourable outcomes: integration of care and peer supporters increased enrolment into HIV care, medical incentives increased pre-ART retention, POC CD4 testing and food incentives increased completion of ART eligibility screening and ART initiation. Most studies focused on the general adult patient population or pregnant women. The majority of published studies were observational cohort studies, subject to an unclear risk of bias.

CONCLUSIONS

Findings suggest that streamlining services to minimize patient visits, providing adequate medical and peer support, and providing incentives may decrease attrition, but the quality of the current evidence base is low. Few studies have investigated combined interventions, or assessed the impact of interventions across the HIV cascade. RESULTS from on-going trials investigating POC CD4 count testing, patient navigation, rapid ART initiation and mobile phone technology may fill the quality of evidence gap. Further high-quality studies on key population groups are required, with interventions informed by previously reported barriers to care.

Development, calibration and performance of an HIV transmission model incorporating natural history and behavioral patterns: application in South Africa

Understanding HIV transmission dynamics is critical to estimating the potential population-wide impact of HIV prevention and treatment interventions. We developed an individual-based simulation model of the heterosexual HIV epidemic in South Africa and linked it to the previously published Cost-Effectiveness of Preventing AIDS Complications (CEPAC) International Model, which simulates the natural history and treatment of HIV. In this new model, the CEPAC Dynamic Model (CDM), the probability of HIV transmission per sexual encounter between short-term, long-term and commercial sex worker partners depends upon the HIV RNA and disease stage of the infected partner, condom use, and the circumcision status of the uninfected male partner. We included behavioral, demographic and biological values in the CDM and calibrated to HIV prevalence in South Africa pre-antiretroviral therapy. Using a multi-step fitting procedure based on Bayesian melding methodology, we performed 264,225 simulations of the HIV epidemic in South Africa and identified 3,750 parameter sets that created an epidemic and had behavioral characteristics representative of a South African population pre-ART. Of these parameter sets, 564 contributed 90% of the likelihood weight to the fit, and closely reproduced the UNAIDS HIV prevalence curve in South Africa from 1990–2002. The calibration was sensitive to changes in the rate of formation of short-duration partnerships and to the partnership acquisition rate among high-risk individuals, both of which impacted concurrency. Runs that closely fit to historical HIV prevalence reflect diverse ranges for individual parameter values and predict a wide range of possible steady-state prevalence in the absence of interventions, illustrating the value of the calibration procedure and utility of the model for evaluating interventions. This model, which includes detailed behavioral patterns and HIV natural history, closely fits HIV prevalence estimates.

Heterogeneous HIV testing preferences in an urban setting in Tanzania: results from a discrete choice experiment

BACKGROUND

Efforts to reduce Human Immunodeficiency Virus (HIV) transmission through treatment rely on HIV testing programs that are acceptable to broad populations. Yet, testing preferences among diverse at-risk populations in Sub-Saharan Africa are poorly understood. We fielded a population-based discrete choice experiment (DCE) to evaluate factors that influence HIV-testing preferences in a low-resource setting.

METHODS

Using formative work, a pilot study, and pretesting, we developed a DCE survey with five attributes: distance to testing, confidentiality, testing days (weekday vs. weekend), method for obtaining the sample for testing (blood from finger or arm, oral swab), and availability of HIV medications at the testing site. Cluster-randomization and Expanded Programme on Immunization (EPI) sampling methodology were used to enroll 486 community members, ages 18-49, in an urban setting in Northern Tanzania. Interviewer-assisted DCEs, presented to participants on iPads, were administered between September 2012 and February 2013.

RESULTS

Nearly three of five males (58%) and 85% of females had previously tested for HIV; 20% of males and 37% of females had tested within the past year. In gender-specific mixed logit analyses, distance to testing was the most important attribute to respondents, followed by confidentiality and the method for obtaining the sample for the HIV test. Both unconditional assessments of preferences for each attribute and mixed logit analyses of DCE choice patterns suggest significant preference heterogeneity among participants. Preferences differed between males and females, between those who had previously tested for HIV and those who had never tested, and between those who tested in the past year and those who tested more than a year ago.

CONCLUSION

The findings suggest potentially significant benefits from tailoring HIV testing interventions to match the preferences of specific populations, including males and females and those who have never tested for HIV.

What lies behind gender inequalities in HIV/AIDS in sub-Saharan African countries: evidence from Kenya, Lesotho and Tanzania

Within sub-Saharan Africa, women are disproportionately at risk for acquiring and having human immunodeficiency virus (HIV)/acquired immunodeficiency syndrome (AIDS). It is important to clarify whether gender inequalities in HIV prevalence in this region are explained by differences in the distributions of HIV risk factors, differences in the effects of these risk factors or some combination of both. We used an extension of the Blinder-Oaxaca decomposition approach to explain gender inequalities in HIV/AIDS in Kenya, Lesotho and Tanzania using data from the demographic and health and AIDS indicator surveys. After adjusting for covariates using Poisson regression models, female gender was associated with a higher prevalence of HIV/AIDS in Kenya [prevalence ratio (PR) = 1.73, 95% confidence interval (CI) = 1.33, 2.23 in 2003] and Lesotho (PR = 1.39, 95% CI = 1.20, 1.62 in 2004/05), but not in Tanzania. Decomposition analyses demonstrated two distinct patterns over time. In Tanzania, the gender inequality in HIV/AIDS was explained by differences in the distributions of HIV risk factors between men and women. In contrast, in Kenya and Lesotho, this inequality was partly explained by differences in the effects across men and women of measured HIV/AIDS risk factors, including socio-demographic characteristics (age and marital status) and sexual behaviours (age at first sex); these results imply that gender inequalities in HIV/AIDS would persist in Kenya and Lesotho even if men and women had similar distributions of HIV risk factors. The production of gender inequalities may vary across countries, with inequalities attributable to the unequal distribution of risk factors among men and women in some countries and the differential effect of these factors between groups in others. These different patterns have important implications for policies to reduce gender inequalities in HIV/AIDS.

Antiretroviral therapy for prevention of HIV transmission: implications for Europe

The aim of this review is to summarise the evidence on the population-level effect of antiretroviral therapy (ART) in preventing HIV infections, and to discuss potential implications in the European context of recommending starting ART when the CD4 count is above 350 cells/mm3. The ability of ART to reduce the risk of HIV transmission has been reported in observational studies and in a randomised controlled trial (HPTN 052), in which ART initiation reduced HIV transmission by 96% within serodiscordant couples. As yet, there is no direct evidence for such an effect among men having sex with men or people who inject drugs. HPTN 052 led international organisations to develop recommendations with a higher CD4 threshold for ART initiation. However, there remains a lack of strong evidence of clinical benefit for HIV-positive individuals starting ART with CD4 count above 350 cells/mm3. The main goal of ART provision should be to increase ART coverage for all those in need, based on the current guidelines, and the offer of ART to those who wish to reduce infectivity; increased HIV testing is therefore a key requirement. Other proven prevention means such as condom use and harm reduction for people who inject drugs remain critical.

Balancing efficiency, equity and feasibility of HIV treatment in South Africa - development of programmatic guidance

South Africa, the country with the largest HIV epidemic worldwide, has been scaling up treatment since 2003 and is rapidly expanding its eligibility criteria. The HIV treatment programme has achieved significant results, and had 1.8 million people on treatment per 2011. Despite these achievements, it is now facing major concerns regarding (i) efficiency: alternative treatment policies may save more lives for the same budget; (ii) equity: there are large inequalities in who receives treatment; (iii) feasibility: still only 52% of the eligible population receives treatment.Hence, decisions on the design of the present HIV treatment programme in South Africa can be considered suboptimal. We argue there are two fundamental reasons to this. First, while there is a rapidly growing evidence-base to guide priority setting decisions on HIV treatment, its included studies typically consider only one criterion at a time and thus fail to capture the broad range of values that stakeholders have. Second, priority setting on HIV treatment is a highly political process but it seems no adequate participatory processes are in place to incorporate stakeholders' views and evidences of all sorts.We propose an alternative approach that provides a better evidence base and outlines a fair policy process to improve priority setting in HIV treatment. The approach integrates two increasingly important frameworks on health care priority setting: accountability for reasonableness (A4R) to foster procedural fairness, and multi-criteria decision analysis (MCDA) to construct an evidence-base on the feasibility, efficiency, and equity of programme options including trade-offs. The approach provides programmatic guidance on the choice of treatment strategies at various decisions levels based on a sound conceptual framework, and holds large potential to improve HIV priority setting in South Africa.

Elimination of HIV in South Africa through expanded access to antiretroviral therapy: a model comparison study

BACKGROUND

Expanded access to antiretroviral therapy (ART) using universal test and treat (UTT) has been suggested as a strategy to eliminate HIV in South Africa within 7 y based on an influential mathematical modeling study. However, the underlying deterministic model was criticized widely, and other modeling studies did not always confirm the study's finding. The objective of our study is to better understand the implications of different model structures and assumptions, so as to arrive at the best possible predictions of the long-term impact of UTT and the possibility of elimination of HIV.

METHODS AND FINDINGS

We developed nine structurally different mathematical models of the South African HIV epidemic in a stepwise approach of increasing complexity and realism. The simplest model resembles the initial deterministic model, while the most comprehensive model is the stochastic microsimulation model STDSIM, which includes sexual networks and HIV stages with different degrees of infectiousness. We defined UTT as annual screening and immediate ART for all HIV-infected adults, starting at 13% in January 2012 and scaled up to 90% coverage by January 2019. All models predict elimination, yet those that capture more processes underlying the HIV transmission dynamics predict elimination at a later point in time, after 20 to 25 y. Importantly, the most comprehensive model predicts that the current strategy of ART at CD4 count ≤350 cells/µl will also lead to elimination, albeit 10 y later compared to UTT. Still, UTT remains cost-effective, as many additional life-years would be saved. The study's major limitations are that elimination was defined as incidence below 1/1,000 person-years rather than 0% prevalence, and drug resistance was not modeled.

CONCLUSIONS

Our results confirm previous predictions that the HIV epidemic in South Africa can be eliminated through universal testing and immediate treatment at 90% coverage. However, more realistic models show that elimination is likely to occur at a much later point in time than the initial model suggested. Also, UTT is a cost-effective intervention, but less cost-effective than previously predicted because the current South African ART treatment policy alone could already drive HIV into elimination. Please see later in the article for the Editors' Summary.

Individual-based simulation models of HIV transmission: reporting quality and recommendations

BACKGROUND

Individual-based modeling is a growing technique in the HIV transmission and prevention literature, but insufficient attention has been paid to formally evaluate the quality of reporting in this field. We present reporting recommendations for individual-based models for HIV treatment and prevention, assess the quality of reporting in the existing literature, and comment on the contribution of this model type to HIV policy and prediction.

METHODS

We developed reporting recommendations for individual-based HIV transmission mathematical models, and through a systematic search, used them to evaluate the reporting in the existing literature. We identified papers that employed individual-based simulation models and were published in English prior to December 31, 2012. Articles were included if the models they employed simulated and tracked individuals, simulated HIV transmission between individuals in a particular population, and considered a particular treatment or prevention intervention. The papers were assessed with the reporting recommendations.

FINDINGS

Of 214 full text articles examined, 32 were included in the evaluation, representing 20 independent individual-based HIV treatment and prevention mathematical models. Manuscripts universally reported the objectives, context, and modeling conclusions in the context of the modeling assumptions and the model's predictive capabilities, but the reporting of individual-based modeling methods, parameterization and calibration was variable. Six papers discussed the time step used and one discussed efforts to maintain internal validity in coding.

CONCLUSION

Individual-based models represent detailed HIV transmission processes with the potential to contribute to inference and policy making for many different regions and populations. The rigor in reporting of assumptions, methods, and calibration of individual-based models focused on HIV transmission and prevention varies greatly. Higher standards for reporting of statistically rigorous calibration and model assumption testing need to be implemented to increase confidence in existing and future modeling results.

A randomized trial to optimize HIV/TB care in South Africa: design of the Sizanani trial

BACKGROUND

Despite increases in HIV testing, only a fraction of people newly diagnosed with HIV infection enter the care system and initiate antiretroviral therapy (ART) in South Africa. We report on the design and initial enrollment of a randomized trial of a health system navigator intervention to improve linkage to HIV care and TB treatment completion in Durban, South Africa.

METHODS/DESIGN

We employed a multi-site randomized controlled trial design. Patients at 4 outpatient sites were enrolled prior to HIV testing. For all HIV-infected participants, routine TB screening with sputum for mycobacterial smear and culture were collected. HIV-infected participants were randomized to receive the health system navigator intervention or usual care. Participants in the navigator arm underwent a baseline interview using a strengths-based case management approach to assist in identifying barriers to entering care and devising solutions to best cope with perceived barriers. Over 4 months, participants in the navigator arm received scheduled phone and text messages. The primary outcome of the study is linkage and retention in care, assessed 9 months after enrollment. For ART-eligible participants without TB, the primary outcome is 3 months on ART as documented in the medical record; participants co-infected with TB are also eligible to meet the primary outcome of completion of 6 months of TB treatment, as documented by the TB clinic. Secondary outcomes include mortality, receipt of CD4 count and TB test results, and repeat CD4 counts for those not ART-eligible at baseline. We hypothesize that a health system navigator can help identify and positively affect modifiable patient factors, including self-efficacy and social support, that in turn can improve linkage to and retention in HIV and TB care.

DISCUSSION

We are currently evaluating the clinical impact of a novel health system navigator intervention to promote entry to and retention in HIV and TB care for people newly diagnosed with HIV. The details of this study protocol will inform clinicians, investigators, and policy makers of strategies to best support HIV-infected patients in resource-limited settings.

TRIAL REGISTRATION

Clinicaltrials.gov. unique identifier: NCT01188941.

Evolving uses of oral reverse transcriptase inhibitors in the HIV-1 epidemic: from treatment to prevention

The HIV epidemic continues unabated, with no highly effective vaccine and no cure. Each new infection has significant economic, social and human costs and prevention efforts are now as great a priority as global antiretroviral therapy (ART) scale up. Reverse transcriptase inhibitors, the first licensed class of ART, have been at the forefront of treatment and prevention of mother to child transmission over the past two decades. Now, their use in adult prevention is being extensively investigated. We describe two approaches: treatment as prevention (TasP) - the use of combination ART (2NRTI and 1NNRTI) following HIV diagnosis to limit transmission and pre-exposure prophylaxis (PrEP) –the use of single or dual oral agents prior to sexual exposure. Prevention of mother-to-child transmission using NRTI has been highly successful, though does not involve sustained use of NRTI to limit transmission. Despite theoretical and preliminary support for TasP and PrEP, data thus far indicate that adherence, retention in care and late diagnosis are the major barriers to their successful, sustained implementation. Future advances in drug technologies will be needed to overcome the issue of drug adherence, through development of drugs that involve both less frequent dosing as well as reduced toxicity, possibly through specific targeting of infected cells.

Clinical uncertainties, health service challenges, and ethical complexities of HIV "test-and-treat": a systematic review

Despite the HIV "test-and-treat" strategy's promise, questions about its clinical rationale, operational feasibility, and ethical appropriateness have led to vigorous debate in the global HIV community. We performed a systematic review of the literature published between January 2009 and May 2012 using PubMed, SCOPUS, Global Health, Web of Science, BIOSIS, Cochrane CENTRAL, EBSCO Africa-Wide Information, and EBSCO CINAHL Plus databases to summarize clinical uncertainties, health service challenges, and ethical complexities that may affect the test-and-treat strategy's success. A thoughtful approach to research and implementation to address clinical and health service questions and meaningful community engagement regarding ethical complexities may bring us closer to safe, feasible, and effective test-and-treat implementation.

Identifying HIV most-at-risk groups in Malawi for targeted interventions. A classification tree model

OBJECTIVES

To identify HIV-socioeconomic predictors as well as the most-at-risk groups of women in Malawi.

DESIGN

A cross-sectional survey.

SETTING

Malawi

PARTICIPANTS

The study used a sample of 6395 women aged 15-49 years from the 2010 Malawi Health and Demographic Surveys.

INTERVENTIONS N/A PRIMARY AND SECONDARY OUTCOME MEASURES

Individual HIV status: positive or not.

RESULTS

Findings from the Pearson χ(2) and χ(2) Automatic Interaction Detector analyses revealed that marital status is the most significant predictor of HIV. Women who are no longer in union and living in the highest wealth quintiles households constitute the most-at-risk group, whereas the less-at-risk group includes young women (15-24) never married or in union and living in rural areas.

CONCLUSIONS

In the light of these findings, this study recommends: (1) that the design and implementation of targeted interventions should consider the magnitude of HIV prevalence and demographic size of most-at-risk groups. Preventive interventions should prioritise couples and never married people aged 25-49 years and living in rural areas because this group accounts for 49% of the study population and 40% of women living with HIV in Malawi; (2) with reference to treatment and care, higher priority must be given to promoting HIV test, monitoring and evaluation of equity in access to treatment among women in union disruption and never married or women in union aged 30-49 years and living in urban areas; (3) community health workers, households-based campaign, reproductive-health services and reproductive-health courses at school could be used as canons to achieve universal prevention strategy, testing, counselling and treatment.

Understanding the potential impact of a combination HIV prevention intervention in a hyper-endemic community

OBJECTIVES

Despite demonstrating only partial efficacy in preventing new infections, available HIV prevention interventions could offer a powerful strategy when combined. In anticipation of combination HIV prevention programs and research studies we estimated the population-level impact of combining effective scalable interventions at high population coverage, determined the factors that influence this impact, and estimated the synergy between the components.

METHODS

We used a mathematical model to investigate the effect on HIV incidence of a combination HIV prevention intervention comprised of high coverage of HIV testing and counselling, risk reduction following HIV diagnosis, male circumcision for HIV-uninfected men, and antiretroviral therapy (ART) for HIV-infected persons. The model was calibrated to data for KwaZulu-Natal, South Africa, where adult HIV prevalence is approximately 23%.

RESULTS

Compared to current levels of HIV testing, circumcision, and ART, the combined intervention with ART initiation according to current guidelines could reduce HIV incidence by 47%, from 2.3 new infections per 100 person-years (pyar) to 1.2 per 100 pyar within 4 years and by almost 60%, to 1 per 100 pyar, after 25 years. Short-term impact is driven primarily by uptake of testing and reductions in risk behaviour following testing while long-term effects are driven by periodic HIV testing and retention in ART programs. If the combination prevention program incorporated HIV treatment upon diagnosis, incidence could be reduced by 63% after 4 years and by 76% (to about 0.5 per 100 pyar) after 15 years. The full impact of the combination interventions accrues over 10-15 years. Synergy is demonstrated between the intervention components.

CONCLUSION

High coverage combination of evidence-based strategies could generate substantial reductions in population HIV incidence in an African generalized HIV epidemic setting. The full impact could be underestimated by the short assessment duration of typical evaluations.

Barriers and facilitators to linkage to ART in primary care: a qualitative study of patients and providers in Blantyre, Malawi

Introduction

Linkage from HIV testing and counselling (HTC) to initiation of antiretroviral therapy (ART) is suboptimal in many national programmes in sub-Saharan Africa, leading to delayed initiation of ART and increased risk of death. Reasons for failure of linkage are poorly understood.

Methods

Semi-structured qualitative interviews were undertaken with health providers and HIV-positive primary care patients as part of a prospective cohort study at primary health centres in Blantyre, Malawi. Patients successful and unsuccessful in linking to ART were included.

Results

Progression through the HIV care pathway was strongly influenced by socio-cultural norms, particularly around the perceived need to regain respect lost during a period of visibly declining health. Capacity to call upon the support of networks of families, friends and employers was a key determinant of successful progression. Over-busy clinics, non-functioning laboratories and unsuitable tools used for ART eligibility assessment (WHO clinical staging system and centralized CD4 count measurement) were important health systems determinants of drop-out.

Conclusions

Key interventions that could rapidly improve linkage include guarantee of same-day, same-clinic ART eligibility assessments; utilization of the support offered by peer-groups and community health workers; and integration of HTC and ART programmes.

Human resources needs for universal access to antiretroviral therapy in South Africa: a time and motion study

BACKGROUND

Although access to life-saving treatment for patients infected with HIV in South Africa has improved substantially since 2004, treating all eligible patients (universal access) remains elusive. As the prices of antiretroviral drugs have dropped over the past years, availability of human resources may now be the most important barrier to achieving universal access to HIV treatment in Africa. We quantify the number of HIV health workers (HHWs) required to be added to the current HIV workforce to achieve universal access to HIV treatment in South Africa, under different eligibility criteria.

METHODS

We performed a time and motion study in three HIV clinics in a rural, primary care-based HIV treatment program in KwaZulu-Natal, South Africa, to estimate the average time per patient visit for doctors, nurses, and counselors. We estimated the additional number of HHWs needed to achieve universal access to HIV treatment within one year.

RESULTS

For universal access to HIV treatment for all patients with a CD4 cell count of ≤350 cells/μl, an additional 2,200 nurses, 3,800 counselors, and 300 doctors would be required, at additional annual salary cost of 929 million South African rand (ZAR), equivalent to US$ 141 million. For universal treatment ('treatment as prevention'), an additional 6,000 nurses, 11,000 counselors, and 800 doctors would be required, at an additional annual salary cost of ZAR 2.6 billion (US$ 400 million).

CONCLUSIONS

Universal access to HIV treatment for patients with a CD4 cell count of ≤350 cells/μl in South Africa may be affordable, but the number of HHWs available for HIV treatment will need to be substantially increased. Treatment as prevention strategies will require considerable additional financial and human resources commitments.

Risk factors, barriers and facilitators for linkage to antiretroviral therapy care: a systematic review

OBJECTIVE

To characterize patient and programmatic factors associated with retention in care during the pre-antiretroviral therapy (ART) period and linkage to ART care.

DESIGN

Systematic literature review.

METHODS

An electronic search was conducted on MEDLINE, Global Health, Google Scholar and conference databases to identify studies reporting on predictors, barriers and facilitators of retention in care in the pre-ART period, and linkage to care at three steps: ART-eligibility assessment, pre-ART care and ART initiation. Factors associated with attrition were then divided into areas for intervention.

RESULTS

Seven hundred and sixty-eight citations were identified. Forty-two studies from 12 countries were included for review, with the majority from South Africa (16). The most commonly cited category of factors was transport costs and distance. Stigma and fear of disclosure comprised the second most commonly cited category of factors followed by staff shortages, long waiting times, fear of drug side effects, male sex, younger age and the need to take time off work.

CONCLUSION

This review highlights the importance of investigating interventions that could reduce transport difficulties. Decentralization, task-shifting and integration of services need to be expedited to alleviate health system barriers. Patient support groups and strategic posttest counselling are essential to assist patients deal with stigma and disclosure. Moreover, well tolerated first-line drugs and treatment literacy programmes are needed to improve acceptance of ART. This review suggests a combination of interventions to retain specific groups at risk for attrition such as workplace programmes for employed patients, dedicated clinic and support programmes for men and younger individuals.

The Promise of Antiretrovirals for HIV Prevention

With an estimated 2.6 million new HIV infections diagnosed annually, the world needs new prevention strategies to partner with condom use, harm reduction approaches for injection drug users, and male circumcision. Antiretrovirals can reduce the risk of mother-to-child HIV transmission and limit HIV acquisition after occupational exposure. Macaque models and clinical trials demonstrate efficacy of oral or topical antiretrovirals used prior to HIV exposure to prevent HIV transmission, ie pre-exposure prophylaxis (PrEP). Early initiation of effective HIV treatment in serodiscordant couples results in a 96% decrease in HIV transmission. HIV testing to determine serostatus and identify undiagnosed persons is foundational to these approaches. The relative efficacy of different approaches, adherence, cost and long-term safety will affect uptake and impact of these strategies. Ongoing research will help characterize the role for oral and topical formulations and help quantify potential benefits in sub-populations at risk for HIV acquisition.

Antiviral agents and HIV prevention: controversies, conflicts, and consensus

Antiviral agents can be used to prevent HIV transmission before exposure as preexposure prophylaxis (PrEP), after exposure as postexposure prophylaxis, and as treatment of infected people for secondary prevention. Considerable research has shed new light on antiviral agents for PrEP and for prevention of secondary HIV transmission. While promising results have emerged from several PrEP trials, the challenges of poor adherence among HIV-negative clients and possible increase in sexual risk behaviors remain a concern. In addition, a broader pipeline of antiviral agents for PrEP that focuses on genital tract pharmacology and safety and resistance issues must be developed. Antiretroviral drugs have also been used to prevent HIV transmission from HIV-infected patients to their HIV-discordant sexual partners. The HIV Prevention Trials Network 052 trial demonstrated nearly complete prevention of HIV transmission by early treatment of infection, but the generalizability of the results to other risk groups - including intravenous drug users and MSM - has not been determined. Most importantly, the best strategy for use of antiretroviral agents to reduce the spread of HIV at either the individual level or the population level has not been developed, and remains the ultimate goal of this area of investigation.

Barriers to HIV testing in Côte d'Ivoire: the role of individual characteristics and testing modalities

Background

Expanding HIV testing requires a better understanding of barriers to its uptake. We investigated barriers to HIV testing in Côte d'Ivoire, taking into account test circumstances (client vs. provider-initiated).

Methods

We used data from the 2005 nationally representative Demographic and Health Survey conducted in Côte d'Ivoire. Socio-demographic characteristics, sexual behaviour and knowledge and attitudes toward HIV/AIDS associated with recent (<2 years) HIV testing were identified using gender-specific univariate and multivariate logistic regressions. Among women, differential effects of barriers to testing according to test circumstance (whether they have been offered for a prenatal test or not) were assessed through interaction tests.

Results

Recent HIV testing was reported by 6.1% of men and 9.5% of women (including 4.6% as part of antenatal care). Among men, having a low socioeconomic status, having a low HIV-related knowledge level and being employed [compared to those inactive: adjusted Odds Ratio (aOR) 0.46; 95% confidence interval (CI) 0.25–0.87] were associated with lower proportions of recent HIV testing. Among women without a prenatal HIV testing offer, living outside the capital (aOR 0.38; CI 0.19–0.77) and reporting a unique lifetime sexual partner constituted additional barriers to HIV testing. By contrast, among women recently offered to be tested in prenatal care, none of these variables was found to be associated with recent HIV testing.

Conclusions

Various dimensions of individuals' characteristics constituted significant barriers to HIV testing in Côte d'Ivoire in 2005, with gender specificities. Such barriers are substantially reduced when testing was proposed in the framework of antenatal care. This suggests that provider-initiated testing strategies may help overcome individual barriers to HIV testing.

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.

Achieving universal access for human immunodeficiency virus and tuberculosis: potential prevention impact of an integrated multi-disease prevention campaign in kenya

In 2009, Government of Kenya with key stakeholders implemented an integrated multi-disease prevention campaign for water-borne diseases, malaria and HIV in Kisii District, Nyanza Province. The three day campaign, targeting 5000 people, included testing and counseling (HTC), condoms, long-lasting insecticide-treated bednets, and water filters. People with HIV were offered on-site CD4 cell counts, condoms, co-trimoxazole, and HIV clinic referral. We analysed the CD4 distributions from a district hospital cohort, campaign participants and from the 2007 Kenya Aids Indicator Survey (KAIS). Of the 5198 individuals participating in the campaign, all received HTC, 329 (6.3%) tested positive, and 255 (5%) were newly diagnosed (median CD4 cell count 536 cells/μL). The hospital cohort and KAIS results included 1,284 initial CD4 counts (median 348/L) and 306 initial CD4 counts (median 550/μL), respectively (campaign and KAIS CD4 distributions P = 0.346; hospital cohort distribution was lower P < 0.001 and P < 0.001). A Nyanza Province campaign strategy including ART <350 CD4 cell count could avert approximately 35,000 HIV infections and 1,240 TB cases annually. Community-based integrated public health campaigns could be a potential solution to reach universal access and Millennium Development Goals.

HIV treatment as prevention: systematic comparison of mathematical models of the potential impact of antiretroviral therapy on HIV incidence in South Africa

BACKGROUND

Many mathematical models have investigated the impact of expanding access to antiretroviral therapy (ART) on new HIV infections. Comparing results and conclusions across models is challenging because models have addressed slightly different questions and have reported different outcome metrics. This study compares the predictions of several mathematical models simulating the same ART intervention programmes to determine the extent to which models agree about the epidemiological impact of expanded ART.

METHODS AND FINDINGS

Twelve independent mathematical models evaluated a set of standardised ART intervention scenarios in South Africa and reported a common set of outputs. Intervention scenarios systematically varied the CD4 count threshold for treatment eligibility, access to treatment, and programme retention. For a scenario in which 80% of HIV-infected individuals start treatment on average 1 y after their CD4 count drops below 350 cells/µl and 85% remain on treatment after 3 y, the models projected that HIV incidence would be 35% to 54% lower 8 y after the introduction of ART, compared to a counterfactual scenario in which there is no ART. More variation existed in the estimated long-term (38 y) reductions in incidence. The impact of optimistic interventions including immediate ART initiation varied widely across models, maintaining substantial uncertainty about the theoretical prospect for elimination of HIV from the population using ART alone over the next four decades. The number of person-years of ART per infection averted over 8 y ranged between 5.8 and 18.7. Considering the actual scale-up of ART in South Africa, seven models estimated that current HIV incidence is 17% to 32% lower than it would have been in the absence of ART. Differences between model assumptions about CD4 decline and HIV transmissibility over the course of infection explained only a modest amount of the variation in model results.

CONCLUSIONS

Mathematical models evaluating the impact of ART vary substantially in structure, complexity, and parameter choices, but all suggest that ART, at high levels of access and with high adherence, has the potential to substantially reduce new HIV infections. There was broad agreement regarding the short-term epidemiologic impact of ambitious treatment scale-up, but more variation in longer term projections and in the efficiency with which treatment can reduce new infections. Differences between model predictions could not be explained by differences in model structure or parameterization that were hypothesized to affect intervention impact.

HIV testing and antiretroviral treatment strategies for prevention of HIV infection: impact on antiretroviral drug resistance

'Test and treat' is a strategy in which widespread screening for human immunodeficiency virus (HIV) is followed by immediate antiretroviral therapy for those testing positive, thereby potentially reducing infectiousness in larger cohorts of infected patients. However, there is a concern that test and treat could lead to increased the levels of transmissible drug-resistant HIV, especially if viral load and/or drug resistance is not routinely monitored. Reviews of the existing literature show that up to now, even in the absence of laboratory tests, drug resistance has not created major problems in sub-Saharan Africa. Here, we discuss the current evidence for the effectiveness of a preventive test and treat approach and the challenges and implications for daily clinical practice and public health.

HIV self-testing and the missing linkage

Rochelle Walensky and Ingrid Bassett discuss new research in <I>PLoS Medicine</I> that assessed the feasibility of home-based oral HIV self-testing in Malawi, and suggest that linkage to care must be demonstrated before the success of oral self-testing can be determined.

Harnessing the prevention benefits of antiretroviral therapy to address HIV and tuberculosis

After 30 years we are still struggling to address a devastating HIV pandemic in which over 25 million people have died. In 2010, an estimated 34 million people were living with HIV, around 70% of whom live in sub-Saharan Africa. Furthermore, in 2009 there were an estimated 1.2 million new HIV-associated TB cases, and tuberculosis (TB) accounted for 24% of HIV-related deaths. By the end of 2010, 6.6 million people were taking antiretroviral therapy (ART), around 42% of those in need as defined by the 2010 World Health Organization (WHO) guidelines. Despite this achievement, around 9 million people were eligible and still in need of treatment, and new infections (approximately 2.6 million in 2010 alone) continue to add to the future caseload. This combined with the international fiscal crisis has led to a growing concern regarding weakening of the international commitment to universal access and delivery of the Millennium Development Goals by 2015. The recently launched UNAIDS/WHO Treatment 2.0 platform calls for accelerated simplification of ART, in line with a public health approach, to achieve and sustain universal access to ART, including maximizing the HIV and TB preventive benefit of ART by treating people earlier, in line with WHO 2010 normative guidance. The potential individual and public health prevention benefits of using treatment in the prevention of HIV and TB enhance the value of the universal access pledge from a life-saving initiative, to a strategic investment aimed at ending the HIV epidemic. This review analyzes the gaps and summarizes the evidence regarding ART in the prevention of HIV and TB.

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.