Insights from an individual-level model of HIV programmes in southern Africa: HIV testing, ART and resistance

Antiretroviral therapy (ART) has transformed HIV infection from a death sentence into a chronic condition. In sub-Saharan Africa, the area most affected by this disease, availability of ART has increased dramatically over the last few years. Nevertheless, many people are still not receiving ART either because they are not aware of being HIV-positive or because they struggle to access ART or to engage in HIV care. It is fundamental to take decisions which maximise the health benefits with the limited resources available. When I was writing this thesis, there were countless discussions regarding whether the recommendation on when to start ART had to be modified to a CD4 count threshold higher than 350 cells/μL, given the compelling evidence that ART reduces substantially the risk of transmission in heterosexual serodifferent couples. In this thesis I evaluated the effectiveness and cost-effectiveness of alternative ways of increasing the number of adults receiving ART in South Africa: increasing the CD4 count threshold at which a person is eligible to be initiated on ART, or maintaining the eligibility criteria to CD4 count below 350 cells/μL but expanding the number of people who are diagnosed and engaged in care. In particular, I focused on the impact these two alternatives would have on the development and transmission of resistance. To inform the model on the extent to which NNRTI resistance mutations are present in people who have interrupted NNRTI, I conducted an analysis using data from the UK resistance database. In addition, since I found that the most cost-effective strategy was to expand the number of people engaged in HIV care without modifying the CD4 threshold at which a person is eligible to receive ART, I evaluated at which steps in the current leaky cascade of HIV care it was most cost-effective to intervene. Finally, as new evidence regarding the accuracy and acceptability of HIV self-testing came up, I decided to evaluate the cost-effectiveness of introducing HIV self-testing in a setting such as Zimbabwe

Assessment of the Potential Impact and Cost-effectiveness of Self-Testing for HIV in Low-Income Countries.

Studies have demonstrated that self-testing for human immunodeficiency virus (HIV) is highly acceptable among individuals and could allow cost savings, compared with provider-delivered HIV testing and counseling (PHTC), although the longer-term population-level effects are uncertain. We evaluated the cost-effectiveness of introducing self-testing in 2015 over a 20-year time frame in a country such as Zimbabwe

Preferences for HIV testing services among men who have sex with men in the UK: A discrete choice experiment.

BACKGROUND: In the UK, approximately 4,200 men who have sex with men (MSM) are living with HIV but remain undiagnosed. Maximising the number of high-risk people testing for HIV is key to ensuring prompt treatment and preventing onward infection. This study assessed how different HIV test characteristics affect the choice of testing option, including remote testing (HIV self-testing or HIV self-sampling), in the UK, a country with universal access to healthcare. METHODS AND FINDINGS: Between 3 April and 11 May 2017, a cross-sectional online-questionnaire-based discrete choice experiment (DCE) was conducted in which respondents who expressed an interest in online material used by MSM were asked to imagine that they were at risk of HIV infection and to choose between different hypothetical HIV testing options, including the option not to test. A variety of different testing options with different defining characteristics were described so that the independent preference for each characteristic could be valued. The characteristics included where each test is taken, the sampling method, how the test is obtained, whether infections other than HIV are tested for, test accuracy, the cost of the test, the infection window period, and how long it takes to receive the test result. Participants were recruited and completed the instrument online, in order to include those not currently engaged with healthcare services. The main analysis was conducted using a latent class model (LCM), with results displayed as odds ratios (ORs) and probabilities. The ORs indicate the strength of preference for one characteristic relative to another (base) characteristic. In total, 620 respondents answered the DCE questions. Most respondents reported that they were white (93%) and were either gay or bisexual (99%). The LCM showed that there were 2 classes within the respondent sample that appeared to have different preferences for the testing options. The first group, which was likely to contain 86% of respondents, had a strong preference for face-to-face tests by healthcare professionals (HCPs) compared to remote testing (OR 6.4; 95% CI 5.6, 7.4) and viewed not testing as less preferable than remote testing (OR 0.10; 95% CI 0.09, 0.11). In the second group, which was likely to include 14% of participants, not testing was viewed as less desirable than remote testing (OR 0.56; 95% CI 0.53, 0.59) as were tests by HCPs compared to remote testing (OR 0.23; 95% CI 0.15, 0.36). In both classes, free remote tests instead of each test costing £30 was the test characteristic with the largest impact on the choice of testing option. Participants in the second group were more likely to have never previously tested and to be non-white than participants in the first group. The main study limitations were that the sample was recruited solely via social media, the study advert was viewed only by people expressing an interest in online material used by MSM, and the choices in the experiment were hypothetical rather than observed in the real world. CONCLUSIONS: Our results suggest that preferences in the context we examined are broadly dichotomous. One group, containing the majority of MSM, appears comfortable testing for HIV but prefers face-to-face testing by HCPs rather than remote testing. The other group is much smaller, but contains MSM who are more likely to be at high infection risk. For these people, the availability of remote testing has the potential to significantly increase net testing rates, particularly if provided for free

Evaluating HIV treatment as prevention in the European context

Executive summary The goal of this project is to gather evidence regarding the population-level, and to some extent, individual-level effects of the use of antiretroviral treatment (ART) to prevent HIV infection, and to relate this to current HIV treatment guidelines. To inform the project, formal literature reviews were performed for the three main areas of interest: the effect of antiretroviral therapy in adults on preventing sexual transmission of HIV, prevention of mother-to-child transmission (pMTCT) and post exposure prophylaxis (PEP). The strongest evidence with regard to the effect of treatment of HIV positive individuals to prevent onwards sexual transmission comes from the recent randomised controlled trial (RCT), HPTN052. This study demonstrated that early versus delayed ART led to a 96% relative reduction in onwards linked transmission. Several observational studies of HIV sero-discordant heterosexual couples have also reported that transmission is rare in patients on ART, particularly in those with low HIV-RNA concentrations. However, the findings of HPTN052 and these observational studies are mainly applicable to vaginal heterosexual sex. No direct empirical evidence regarding the relationship between ART use and the risk of HIV transmission through anal intercourse is currently available. Whilst the major HIV treatment guidelines do not explicitly recommend prescribing antiretroviral treatment to prevent onwards transmission, they do not rule out individuals starting ART at a high CD4 count on a case-by-case basis. However, one must also consider the impact of earlier treatment on the HIV positive individual with regard to side effects, and development of drug resistance. Early studies showed that pMTCT regimens containing a single antiretroviral agent (short course zidovudine or single dose nevirapine) or two antiretroviral agents (zidovudine and lamivudine with or without single dose nevirapine) led to clinically important reductions in MTCT rates. However, the most substantial reductions in MTCT rates occurred when combination antiretroviral regimens (more than three antiretroviral drugs) were introduced. These regimens involve the receipt of ART before the third trimester of pregnancy, intrapartum treatment, maternal post-partum treatment and some form of neonatal treatment. There is some evidence from RCTs and extensive evidence from observational studies of the efficacy of these combination regimens, with very low rates of transmission of around 0% to 6%, in settings with no or very little breastfeeding, and 1%-9% when breastfeeding occurs. Furthermore, in settings where avoidance of breastfeeding is not possible, there are a number of studies demonstrating that receipt of maternal and/or neonatal ART during the six months after birth can reduce the risk of perinatal transmissions. All treatment guidelines recommend that HIV-positive pregnant women should receive ART to prevent MTCT, although the exact timing of when ART should begin is not always explicit. Furthermore, where mentioned, use of neonatal ART is also recommended, regardless of whether infants are breastfed. Much of the data supporting the use of PEP are based on animal models, which suggest that PEP is most efficacious if commenced as soon as possible after exposure. When considering occupational exposure to HIV, human studies are limited, as no RCTs exist for ethical reasons. Evidence for efficacy is based on one case control study which demonstrated an 81% reduction in transmission of HIV through the use of zidovudine. Other studies have demonstrated that PEP following occupational exposure is not always effective and there are cases of PEP failure. Similarly, there are also no RCTs assessing the efficacy of PEP for prevention of HIV transmission after sexual exposure, and limited evidence from observational data. Most treatment guidelines agree that PEP is not always effective and PEP policies need to emphasise the importance of risk prevention in the first place in all settings where there is a risk of HIV transmission. Side effects are not uncommon when using PEP, so it is important to consider carefully whether an individual should receive PEP and some studies have suggested that increase in availability of PEP may lead to an increase in risky sex behaviour. Antiretroviral treatment has well documented benefits in reducing transmission of HIV and, in particular, has had a major population level impact on HIV acquisition in children from HIV positive mothers. Further research is needed to help us understand how we can best use ART to prevent HIV infections through other transmission routes, and to develop evidence-based policy recommendations, particularly in the European context

Changes in chemsex and sexual behaviour over time, among a cohort of MSM in London and Brighton: Findings from the AURAH2 study.

BACKGROUND: Recent evidence has suggested that chemsex (the use of mephedrone, crystal methamphetamine and γ -hydroxybutyrate/ γ -butryolactone (GHB/GBL) to enable, enhance and prolong sexual interactions) has increased among men having sex with men (MSM) attending sexual health clinics in large UK cities. To date there has been no data from the UK or Europe that describes changes in chemsex over time within a cohort of MSM. METHODS: The prospective cohort study, Attitudes to and Understanding Risk of Acquisition of HIV over Time (AURAH2), collected online questionnaire data from HIV negative or undiagnosed MSM (at enrolment) from 2015 to 2018, recruited from sexual health clinics. We aim to investigate changes in chemsex, three individual drugs associated with chemsex, frequency of chemsex sessions and measures of sexual behaviour, among the cohort of MSM over the study's 3 year follow-up period. RESULTS: In total 622 MSM completed at least one online questionnaire for the AURAH2 study, of which 400 (64.3%) were still engaged with the study within the last six months of follow-up. Prevalence of chemsex significantly declined during the follow-up from 31.8% (198/622) at the first online questionnaire, to 11.1% (8/72; p < 0.001) at the 9th. This decline was reflected in the proportion of MSM reporting use of two of the three individual chemsex drugs: mephedrone use had significantly declined from 25.2% at the first online questionnaire to 9.7% (p < 0.001) at the 9th, GHB/GBL use had also declined from 19.9% to 8.3% (p = 0.001). While crystal methamphetamine use declined, but not significantly (11.1%-6.9% [p = 0.289]). Most measures of sexual behaviour (any anal sex, group sex, recent HIV test and bacterial STI) also tended to decline over the follow-up period, with the exception of CLAI with more than one and more than two partners. CONCLUSIONS: Chemsex and use of two individual chemsex drugs (mephedrone and GHB/GBL) significantly declined over time among individuals in the study, alongside most measures of sexual behaviour with the exception of those related to CLAI. Focusing health promotion and HIV prevention, such as awareness of post-exposure prophylaxis (PEP) and access to pre-exposure prophylaxis (PrEP), on MSM that report chemsex, and in particular problematic chemsex, would be highly beneficial, potentially only necessary for a relatively short period of time for individuals, and could have long term benefits for HIV and STI prevention

Attitudes to and Understanding of Risk of Acquisition of HIV Over Time: Design and Methods for an Internet-based Prospective Cohort Study Among UK Men Who Have Sex With Men (the AURAH2 Study)

Background: The annual number of new HIV infections among men who have sex with men (MSM) has risen in the UK and, of those HIV positive, the proportion undiagnosed is high. The prospective AURAH2 study aims to assess factors associated with HIV acquisition among MSM in the UK, and to investigate changes over time within individuals in sexual behaviour and HIV-testing practices. / Methods/Design: AURAH2 is a prospective study among MSM without diagnosed HIV, aiming to recruit up to 1000 sexually active MSM attending sexual health clinics in London and Brighton. Participants complete an initial paper-based questionnaire, followed by four monthly online follow-up questionnaires collecting socio-demographic, health and behavioural data, including sexual behaviour, recreational and other drug use, HIV testing practices and Pre-Exposure Prophylaxis use, over a planned three year period. / Discussion: The results from AURAH2 study will provide an important insight into established and emerging risk behaviours that may be associated with acquisition of HIV in MSM, in the UK, changes over time within individuals in sexual behaviour, and inform on HIV testing practices. This data will be crucial to inform future HIV prevention strategies