Background: Implementation studies demonstrated that it is possible to substantially reduce the leakages at different steps of the cascade of care. Our aim is to evaluate the effectiveness of potential improvements in each step and of changing the eligibility criteria to initiate ART (EC) in South Africa.
Methodology: The ‘HIV Synthesis’ model calibrated to South Africa was used. By the end of 2013 it is assumed 62% of the population ever tested for HIV, 29% in the last year, 71% are linked to care (LK) by 1 year since diagnosis, 42% of those not eligible at staging are retained in pre-ART care (RPC) at 1 year, EC is CD4<350 cells/μ, 84% are retained on ART (RA) at 1 year since initiation and the median time to switch to 2nd line after virological failure is 12 months. The maintenance of this status is referred to as R. The following improvements, implemented over 2014 and 2015, are considered: EC of CD4<500 cells/μ (F), EC at diagnosis (D), increase in HIV testing so that 85% ever tested for HIV (T), reduction in loss at diagnosis so that 85% are LK (L), improvements in pre-ART retention, so that 72% are RPC (P), improvements in retention on ART, so that 92% are RA (A), reduction in the time to switching to 2nd line to 5 months (S). In addition the following combination of the above are considered: improvement in T with change in EC to CD4 <500 cells/μ (TF) and at diagnosis (TD); improvement in LK and RPC with EC respectively CD4<350 cells/μ (LP), <500 cells/μ (LPF) and at diagnosis (LPD); as LP with improvement in HIV testing and on ART (TLPA); as TLPA with EC at CD4<500 cells/μ (TLPAF) and at diagnosis(TLPAD); improvements at all steps with EC at CD4<350 cells/μ (TLPAS), <500 cells/μ (TLPASF) and at diagnosis (TLPASD).
Results: The single improvement which leads to the highest increment in life-years over 20 years is the improvement in retention on ART (7.6 million), which leads to the greatest reduction in deaths among HIV+ (930,000). Modifying the EC to initiate ART at diagnosis saves the highest number of HIV infections (760,000), but results in an increment in lifeyears of 3.5 million. Improvements at all steps of the cascade allow gaining over 15 million life-years over 20 years.
Conclusions: Our modelling helps to understand which interventions will have the biggest impact on maximising life years, and shows that improving retention on ART has the greatest impact. Cost-effectiveness analysis could help to identify which interventions would represent value for money from limited health sector resources.