Behavioural trajectories following DAA treatment for HCV among people with HIV: findings from an international consortium of prospective cohort studies.

Objective Examine the proportion of people with HIV engaging in behaviours associated with hepatitis C virus (HCV) infection after successful direct-acting antiviral (DAA) treatment and establish longitudinal patterns of behavioural risk over time.Design Multinational, prospective cohort study (International Collaboration on Hepatitis C Elimination in HIV Cohorts).Methods Individuals with HIV successfully treated with DAAs and ≥2 follow-up visits with behavioural data were included. Changes in the proportion of any risk behaviour after treatment, which included sexual and drug use behaviours, were analysed using logistic regression with generalized estimating equations. We identified distinct trajectories of any risk behaviour over time using group-based trajectory models (GBTM).Results Of the 1,477 individuals included, 487 (33.0%) were people who inject drugs, 378 (25.6%) were men who have sex with men and 442 (29.9%) were both. During a median 2.7 years (IQR=1.6-3.9) of follow-up, the proportion engaging in any risk behaviour slightly decreased over time (adjusted odds ratio per half year=0.97, 95% confidence interval=0.95-0.99). GBTM revealed four distinct behavioural trajectories: consistently low (n=433, 29.3% of total population), moderate at baseline and increasing (n = 119, 8.1%), high at baseline and decreasing (n = 184, 12.5%) and consistently high (n = 741, 50.2%).Conclusions Despite slight decreases in behaviours following successful DAA treatment, half of individuals had a consistently high probability of behaviours that put them at risk of HCV reinfection over time. As reinfections comprise a growing proportion of new incident HCV cases, these findings underscore the importance of ongoing primary prevention measures alongside testing and retreatment to eliminate HCV.