Sexual and drug use risk behaviour trajectories among people treated for recent HCV infection: the REACT study

INTRODUCTION: Exploration of sexual and drug use behaviours following treatment for recent hepatitis C virus (HCV) is limited. This analysis modelled behavioural trajectories following treatment for recent HCV and assessed reinfection. METHODS: Participants treated for recent HCV in an international trial (enrolled 2017–2019) were followed at 3‐monthly intervals for up to 2 years to assess longitudinal behaviours. Population‐averaged changes were assessed using generalized estimating equations. Distinct behavioural trajectories were identified using group‐based trajectory modelling. HCV reinfection incidence was calculated using person‐years (PY) of observation. RESULTS: During the follow‐up of 212 participants (84% gay and bisexual men [GBM]; 69% HIV; 26% current injecting drug use [IDU]), behavioural trajectories for IDU and stimulant use (past month) did not change. However, population‐averaged decreases in the likelihood of daily IDU (adjusted odds ratio [AOR] 0.83; 95% CI 0.72, 0.95) and opioid use (AOR 0.84; 95% CI 0.75, 0.93) were observed. Among GBM, behavioural trajectories for chemsex did not change. Population‐averaged decreases in condomless anal intercourse with casual male partners (CAI‐CMP) (AOR 0.95; 95% CI 0.90, 0.99) and group‐sex (AOR 0.86; 95% CI 0.80, 0.93) were observed, but masked distinct trajectories. While a proportion had a decreased probability of CAI‐CMP (23%) and group‐sex (59%) post‐treatment, a substantial proportion retained a high probability of these behaviours. High HCV reinfection incidence was observed for the sustained high probability IDU (33.0/100 PY; 95% CI 17.7, 61.3) and chemsex (23.3/100 PY; 95% CI 14.5, 37.5) trajectories. CONCLUSIONS: Limited sexual and drug use behavioural change was observed following treatment for recent HCV, supporting access to surveillance and (re)treatment.