BACKGROUND: Successful treatment of hepatitis C virus (HCV) can lead to liver fibrosis regression. It is not known who will experience fibrosis regression or how quickly it will occur. METHODS: We modelled transient elastography (TE) measurements from 1470 HIV-HCV coinfected participants followed in cohorts contributing data to InCHEHC, an international collaboration. Participants were eligible if they had at least one TE measurement in the year prior to starting a successful direct acting antiviral treatment for HCV. This measurement was used to classify participants into one of three fibrosis subgroups. We analysed measurement sequences in each subgroup using a covariate adjusted generalised additive mixed model, with an adaptive spline representing changes in the mean measurement before, during and after treatment. RESULTS: Each fibrosis subgroup had a distinctly different response. Most participants with cirrhosis (F4, TE ≥14.6 KPa) prior to HCV treatment did not show meaningful fibrosis regression - almost 70% were predicted to remain above 12 KPa three years after treatment ended. Participants with significant fibrosis (F2-F3, TE ≥7.2 and <14.6KPa) showed appreciable regression in the first two years after treatment, falling on average to levels below 7.2 KPa. Those without fibrosis prior to treatment (F0-F1) did not progress. CONCLUSION: Most coinfected people with cirrhosis prior to HCV cure will remain cirrhotic. For those with significant fibrosis, regression can be expected within two years to levels not normally associated with an increased risk of endstage liver disease. A TE measurement two years after cure should give a reliable estimate of residual fibrosis.< Leer menos