OBJECTIVES : Current antiretroviral therapy (ART) has dramatically improved outcomes for people living with HIV (PLWH), but requires daily dosing, making adherence to treatment a significant challenge for some patients. The availability of new, long-acting (LA), injection-based ART regimens which will be administered by healthcare professionals as directly observed therapy (DOT) may improve adherence to ART and clinical outcomes in PLWH. This study models the potential impact of improved adherence and reduced subsequent HIV transmission with LA DOT.

METHODS : A previously published decision tree and Markov cohort state-transition model was adapted to model the impact of treatment adherence and disease transmission. Health states were defined by viral load and CD4 cell count. As LA DOT removes the need for adherence to daily dosing, the efficacy of LA DOT was modelled independent of adherence whereas virologic suppression in the standard of care arm was adjusted to reflect published data on adherence to daily dosing. A Canadian perspective was adopted, with costs and quality-adjusted life-years (QALYs) discounted annually at a rate of 1.5%.

RESULTS : Eliminating suboptimal adherence among PLWH in Canada (average adherence is 8.12% below the optimal levels observed in clinical trials) averted 4 (240) new HIV cases per 1,000 persons treated (overall in Canada), achieved lifetime cost-savings of $154,643 ($9.8 million) as well as QALY and life-year gains of 100 (6,341) and 134 (8,457), respectively. Greater benefits were estimated when assessing the impact in subgroups with lower adherence; such as women, younger adults or people with aboriginal ancestry.

CONCLUSIONS : Studies evaluating LA DOT ART need to account for the impact of adherence and reduced subsequent disease transmission. Providing PLWH and healthcare providers with novel modes of ART administration that enhance individualisation of treatment may facilitate achievement of UNAIDS 95-95-95 objectives.