Implications for a policy of initiating antiretroviral therapy in people diagnosed with human immunodeficiency virus: the CAPRA research programme

Background: More than 100,000 people in the UK are living with a human immunodeficiency virus (HIV) infection. There are currently estimated to be around 4000 people newly infected in the UK per year, mostly men who have sex with men (MSM). It has become increasingly clear that antiretroviral therapy (ART) used to treat people infected with HIV also has a profound effect on infectivity. At the initiation of the programme, it was the policy in the UK to initiate ART in people when their cluster of differentiation 4 (CD4) count was approaching 350/µl. Objectives: To assess what would be the effectiveness and cost-effectiveness of a policy of immediate initiation of ART at diagnosis among MSM, taking into account the potential reductions in new infections. Design: We calibrated an individual-based model of HIV transmission, progression and the effect of ART in MSM, informed by a series of studies on sexual behaviour in relation to ART use and the transmission risk in people with viral suppression on ART, and by surveillance data collected by Public Health England. Setting, participants and interventions: The series of studies used to inform the model included (1) the Antiretrovirals, Sexual Transmission Risk and Attitudes (ASTRA) study, a cross-sectional self-administered questionnaire study of people diagnosed with HIV attending eight HIV outpatient clinics in the UK (2011–12); (2) the Cognitive Impairment in People with HIV in the European Region (CIPHER) study, a study of levels of neurocognitive impairment in HIV-positive ASTRA participants and people from HIV clinics in Rome, Copenhagen and Minsk; (3) the Attitudes to, and Understanding of, Risk of Acquisition of HIV (AURAH) study, a cross-sectional self-administered questionnaire study of individuals who have not been diagnosed as HIV-positive attending 20 genitourinary medicine clinics across the UK (2013–14); (4) a substudy of sexual behaviour among individuals enrolled in an open-label multicentre international randomised trial (from 2013) of immediate versus deferred ART (to CD4 cell counts of 350/µl) in people with CD4 cell counts of > 500/µl [the Strategic Timing of Antiretroviral Therapy (START) trial]; and (5) Partners of People on ART: a new Evaluation of the Risks (PARTNER), an observational multicentre longitudinal study of HIV serodifferent heterosexual and MSM couples, in which the HIV-positive partner is on ART (2010–14). Main outcome measures: The main outcome measures were the clinical effectiveness and cost-effectiveness of a policy of immediate initiation of ART at diagnosis. Results: Based on data from studies (i)–(v), we estimated from our modelling work that increases in condomless sex (CLS) among MSM as a whole may explain the increase in HIV infection incidence in MSM epidemics over a time when ART coverage and viral suppression increased, demonstrating the limiting effects of non-condom use on the HIV epidemic among MSM. Accordingly, an increase in the overall proportion of MSM living with HIV who are virally suppressed on ART from the current level of 500/µl, supporting ART initiation in people diagnosed with a HIV infection. Future work: There is a need for future research into the means of increasing the frequency with which MSM test for HIV. Funding: The National Institute for Health Research Programme Grants for Applied Research programme.