The relative cost-effectiveness of long-acting injectable cabotegravir versus oral pre-exposure prophylaxis: a modelled economic evaluation and threshold analysis in South Africa based on the HPTN 083 and 084 trials


BACKGROUND: Long-acting cabotegravir (CAB-LA), administered 2-monthly, is more effective at preventing HIV infection than daily oral tenofovir (TDF)/emtricitabine (FTC), but its cost-effectiveness in a high-prevalence setting is not known. We estimated the cost-effectiveness of CAB-LA compared to TDF/FTC in South Africa and determined the threshold price at which CAB-LA is as cost-effective as TDF/FTC.
METHODS: We used deterministic HIV transmission modelling, evaluating the impact of CAB-LA provision compared to scaling up standard-of-care, TDF/FTC, to adolescent girls, young women, female sex workers, adolescent boys, young men, and men who have sex with men. We estimated the average cost by population using ingredients-based costing (costs in 2021 USD). We model the cost-effectiveness over 2022-2041, assuming two coverage scenarios (medium, high), assuming higher uptake of CAB-LA compared to TDF/FTC throughout based on preference studies. Under CAB-LA we modelled two scenarios defined by average duration of use (minimum: same duration as TDF/FTC of 5-11 months; maximum: longer duration than TDF/FTC, 12-24 months). We compare scenarios to the current baseline of low TDF/FTC roll-out.
RESULTS: Across CAB-LA scenarios, 15%-28% of new HIV infections were averted over baseline compared to 5%-8% in oral TDF/FTC scale-up scenarios (Table 1). Assuming equivalent drug costs between CAB-LA and TDF/FTC, the incremental cost of CAB-LA to the HIV programme was higher than TDF/FTC (5%-14% vs 2%-4%) due to higher assumed uptake of CAB-LA. The cost per infection averted was $4,553-$6,803 (CAB-LA) and $6,053-$6,610 (TDF/FTC). The cost per CAB-LA injection needed to be less than twice that of a 2-month supply of TDF/FTC to remain as cost-effective, with threshold prices ranging between $8.99/injection (high coverage; maximum duration) and $14.21/injection (medium coverage; minimum duration).

CONCLUSIONS: CAB-LA is potentially game-changing for HIV prevention. However, for its implementation to be financially feasible across low- and middle-income countries with high HIV incidence, CAB-LA must be reasonably priced.