BACKGROUND: In Canada, the incidence of HIV increased by 24.9% between 2021 and 2022. Cabotegravir long-acting (CAB-LA) injectable, the first long-acting injectable, administered every two months was approved in Canada (May 2024) as pre-exposure prophylaxis (PrEP) to reduce the risk of sexually acquired HIV infection in at-risk adults and adolescents, including men who have sex with men (MSM), transgender women (TGW), and cisgender women (CGW). The HIV Prevention Trials Network (HPTN) 083 (MSM and TGW) and HPTN 084 (CGW) studies demonstrated the superiority of every two-month CAB-LA versus daily oral tenofovir disoproxil fumarate/emtricitabine (TDF/FTC) for PrEP.
METHODS: A decision-analytic Markov model was used to estimate the lifetime clinical and economic impact of CAB-LA compared with oral TDF/FTC and no PrEP from a Canadian public payer perspective. Modelled individuals initiated a PrEP option (CAB-LA, TDF/FTC, or no PrEP) upon model entry and continued to receive their initially assigned PrEP option until discontinuation, HIV acquisition, or death. Secondary HIV seroconversions related to onward transmission were also estimated in the model. An indirect treatment comparison including the HPTN-083 and -084 studies provided estimate of the effectiveness of CAB-LA vs. no PrEP based on the observed effectiveness of CAB-LA vs. TDF/FTC and the predicted effectiveness of TDF/FTC vs. no PrEP.
RESULTS: The number needed to treat (NNT) to prevent one primary HIV infection over the modelled lifetime was 13 for CAB-LA and 19 for TDF/FTC compared with No PrEP; compared with TDF/FTC, the NNT was 37 with CAB-LA. CAB-LA was less costly ($174,847) and more effective (36.86 QALYs) than TDF/FTC ($192,328; 36.67 QALYs) and no PrEP ($261,682; 36.29 QALYs). These values resulted in incremental cost savings of $17,481 and QALY gains of 0.20 versus TDF/FTC, and $86,835 and 0.57 versus no PrEP (Table 1). CAB-LA would be the dominant PrEP option based on the $50,000 willingness-to-pay threshold in Canada.
CONCLUSION: Overall, compared to TDF/FTC and no PrEP, the results indicate the introduction of CAB-LA as PrEP in Canada would result in substantial public health and monetary benefits by preventing additional HIV infections and reducing the clinical and economic burden of HIV.
