Incidence of hepatitis C virus infection in the prison setting: The SToP-C study.

People in prison are at high risk of HCV given high injecting drug use prevalence. This study evaluated HCV incidence and associated injecting drug use characteristics in prison. The SToP-C study enrolled people incarcerated in four Australian prisons. Participants were tested for HCV at enrolment and then every 3-6 months (October-2014 to November-2019). Participants eligible for this analysis included those at-risk of HCV primary infection (anti-HCV negative) or re-infection (anti-HCV positive, HCV RNA negative) with follow-up assessment. A total of 1643 eligible participants were included in analyses (82% male; median age 33 years; 30% injected drugs in prison; 1818 person-years of follow-up). Overall HCV incidence was 6.11/100 person-years (95%CI: 5.07-7.35), with higher rate of re-infection (9.34/100 person-years; 95%CI: 7.15-12.19) than primary infection (4.60/100 person-years; 95%CI: 3.56-5.96). In total population (n = 1643), HCV risk was significantly higher among participants injecting drugs in prison [vs. no injecting; adjusted hazard ratio (aHR): 10.55, 95%CI: 5.88-18.92), and those who were released and re-incarcerated during follow-up (vs. remained incarcerated; aHR: 1.60, 95%CI: 1.03-2.49). Among participants who injected recently (during past month, n = 321), HCV risk was reduced among those receiving high-dosage opioid agonist therapy (OAT), i.e. methadone ≥60 mg/day or buprenorphine ≥16 mg/day, (vs. no OAT, aHR: 0.11, 95%CI: 0.02-0.80) and increased among those sharing needles/syringes without consistent use of disinfectant to clean injecting equipment (vs. no sharing, HR: 4.60, 95%CI: 1.35-15.66). This study demonstrated high HCV transmission risk in prison, particularly among people injecting drugs. High-dosage OAT was protective, but improved OAT coverage and needle/syringe programmes to reduce sharing injecting equipment are required.

Screening for Hepatitis C Virus Reinfection Using a Behaviour-Based Risk Score among Men Who Have Sex with Men with HIV: Results from a Case-Control Diagnostic Validation Study.

We assessed the predictive capacity of the HCV-MOSAIC risk score, originally developed for primary early HCV infection, as a screening tool for HCV reinfection in 103 men who have sex with men (MSM) with HIV using data from the MOSAIC cohort, including MSM with HIV/HCV-coinfection who became reinfected (cases, n = 27) or not (controls, n = 76) during follow-up. The overall predictive capacity of the score was assessed using the area under the receiver operating characteristic (AUROC) curve. The effects of covariates on the receiver operating characteristic (ROC) curve were assessed using parametric ROC regression. The score cut-off validated for primary early infection (≥2.0) was used, from which the sensitivity and specificity were calculated. The AUROC was 0.74 (95% confidence interval (CI) = 0.63-0.84). Group sex significantly increased the predictive capacity. Using the validated cut-off, sensitivity was 70.4% (95%CI = 49.8-86.2%) and specificity was 59.2% (95%CI: 47.3-70.4%). External validation from a cohort of 25 cases and 111 controls, all MSM with HIV, resulted in a sensitivity of 44.0% (95%CI = 24.4-65.1) and specificity of 71.2% (95%CI = 61.8-79.4). The HCV-MOSAIC risk score may be useful for identifying individuals at risk of HCV reinfection. In sexual health or HIV-care settings, this score could help guide HCV-RNA testing in MSM with a prior HCV infection.

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.

Reinfection incidence and risk among people treated for recent hepatitis C virus infection.

OBJECTIVE: Reinfection poses a challenge to hepatitis C virus (HCV) elimination. This analysis assessed incidence of, and factors associated with reinfection among people treated for recent HCV (duration of infection <12 months). METHODS: Participants treated for recent HCV (primary infection or reinfection) in an international randomized trial were followed at 3-monthly intervals for up to 2 years to assess for reinfection. Reinfection incidence was calculated using person-time of observation. Factors associated with HCV reinfection were assessed using Cox proportional hazards regression analysis. RESULTS: Of 222 participants treated for recent HCV, 196 (62% primary infection, 38% reinfection) were included in the cohort at risk for reinfection, of whom 87% identified as gay or bisexual men, 71% had HIV and 20% injected drugs in the month prior to enrolment. During 198 person-years of follow-up, 28 cases of HCV reinfection were identified among 27 participants, for an incidence of 14.2 per 100 person-years [95% confidence interval (CI) 9.8-20.5]. Reinfection was associated with prior HCV reinfection [adjusted hazards ratio (aHR) 2.42; 95% CI 1.08-5.38], injection drug use posttreatment (aHR 2.53; 95% CI 1.14-5.59), condomless anal intercourse with casual male partners (aHR 3.32; 95% CI 1.14-9.65) and geographic region (United Kingdom, aHR 0.21; 95% CI 0.06-0.75). Among gay and bisexual men (GBM), reinfection was also associated with sexualized drug use involving injecting posttreatment (aHR 2.97; 95% CI 1.10-8.02). CONCLUSION: High reinfection incidence following treatment for recent HCV among people with ongoing sexual and drug use risk behaviour highlights the need for posttreatment surveillance, rapid retreatment of reinfection and targeted harm reduction strategies.

Hepatitis C Virus Reinfection in a Real-World Cohort of Homeless-Experienced Individuals in Boston.

BACKGROUND: People experiencing homelessness are disproportionately affected by hepatitis C virus (HCV) infection compared with housed populations. Surveillance for HCV reinfection after successful treatment is a critical step in the care cascade, but limited data on reinfection are available among this highly marginalized group. This study assessed posttreatment reinfection risk in a real-world cohort of homeless-experienced individuals in Boston. METHODS: Individuals receiving HCV direct-acting antiviral treatment through Boston Health Care for the Homeless Program during 2014-2020 with posttreatment follow-up assessment were included. Reinfection was identified based on recurrent HCV RNA at 12 weeks posttreatment with HCV genotype switch or any recurrent HCV RNA following sustain virologic response. RESULTS: A total of 535 individuals were included (81% male, median age 49 years, 70% unstably housed or homeless at treatment initiation). Seventy-four HCV reinfections were detected, including 5 second reinfections. HCV reinfection rate was 12.0/100 person-years (95% confidence interval [CI]: 9.5-15.1) overall, 18.9/100 person-years (95% CI: 13.3-26.7) among individuals with unstable housing and 14.6/100 person-years (95% CI: 10.0-21.3) among those experiencing homelessness. In adjusted analysis, experiencing homelessness (vs stable housing, adjusted hazard ratio, 2.14; 95% CI: 1.09-4.20; P = .026) and drug use within 6 months before treatment (adjusted hazard ratio, 5.23; 95% CI: 2.25-12.13; P < .001) were associated with increased reinfection risk. CONCLUSIONS: We found high HCV reinfection rates in a homeless-experienced population, with increased risk among those homeless at treatment. Tailored strategies to address the individual and systems factors impacting marginalized populations are required to prevent HCV reinfection and to enhance engagement in posttreatment HCV care.

National trends in retreatment of HCV due to reinfection or treatment failure in Australia.

BACKGROUND & AIMS: Population-level uptake of direct-acting antiviral (DAA) treatment for hepatitis C virus (HCV) infection, including retreatment, can be estimated through administrative pharmaceutical dispensation data. However, the reasons for retreatment are not captured in these data. We developed a machine learning model to classify retreatments as reinfection or treatment failure at a national level. METHODS: Retreatment data from the REACH-C cohort (n = 10,843 treated with DAAs; n = 320 retreatments with known reason), were used to train a random forest model. Nested cross validation was undertaken to assess model performance and to optimise hyperparameters. The model was applied to data on DAA retreatment dispensed during 2016-2021 in Australia, to identify the reason for retreatment (treatment failure or reinfection). RESULTS: Average predictive accuracy, precision, sensitivity, specificity and F1-score for the model were 96.3%, 96.5%, 96.3%, 96.3% and 96.3%, respectively. Nationally, 95,272 individuals initiated DAAs, with treatment uptake declining from 32,454 in 2016 to 6,566 in 2021. Of those treated, 6,980 (7%) were retreated. Our model classified 51.8% (95% CI 46.7-53.6%; n = 3,614) of cases as reinfection and 48.2% (95% CI 46.4-53.3%; n = 3,366) as treatment failure. Retreatment for reinfection increased steadily over the study period from 14 in 2016 to 1,092 in 2020, stabilising in 2021. Retreatment for treatment failure increased from 73 in 2016 to 1,077 in 2019, then declined to 515 in 2021. Among individuals retreated for treatment failure, 50% had discontinued initial treatment. CONCLUSIONS: We used a novel methodology with high classification accuracy to evaluate DAA retreatment patterns at a national level. Increases in retreatment uptake for treatment failure corresponded to the availability of pangenotypic and salvage regimens. Increasing retreatment uptake for reinfection likely reflects increasing reinfection incidence. IMPACT AND IMPLICATIONS: This study used machine learning methodologies to analyse national administrative data and characterise trends in HCV retreatment due to reinfection and treatment failure. Retreatment for reinfection increased over time, reflecting increasing numbers of people at risk for reinfection following HCV cure. Increased retreatment for treatment failure corresponded to the availability of pangenotypic and salvage DAA regimens. The findings of this study can be used by public health agencies and policy makers to guide and assess HCV elimination strategies, while the novel methodology for monitoring trends in HCV retreatment has the potential to be used in other settings, and health conditions.

Retreatment for hepatitis C virus direct acting antiviral therapy virological failure in primary and tertiary settings: the REACH-C cohort.

Virological failure occurs in a small proportion of people treated for hepatitis C virus (HCV) with direct-acting antiviral (DAA) therapies. This study assessed retreatment for virological failure in a large real-world cohort. REACH-C is an Australian observational study (n=10843) evaluating treatment outcomes of sequential DAA initiations across 33 health services between March 2016 to June 2019. Virological failure retreatment data were collected until October 2020. Of 408 people with virological failure (81% male; median age 53; 38% cirrhosis; 56% genotype 3), 213 (54%) were retreated once; 15 were retreated twice. A range of genotype specific and pangenotypic DAAs were used to retreat virological failure in primary (n=56) and tertiary (n=157) settings. Following sofosbuvir/velpatasvir/voxilaprevir availability in 2019, the proportion retreated in primary care increased from 21% to 40% and median time to retreatment initiation declined from 294 to 152 days. Per-protocol (PP) sustained virological response (SVR12) was similar for people retreated in primary and tertiary settings (80% vs 81%; p=1.000). In regression analysis, sofosbuvir/velpatasvir/voxilaprevir (vs. other regimens) significantly decreased likelihood of second virological failure (PP SVR12 88% vs. 77%; adjusted odds ratio [AOR] 0.29; 95%CI 0.11-0.81); cirrhosis increased likelihood (PP SVR12 69% vs. 91%; AOR 4.26; 95%CI 1.64-11.09). Indigenous Australians had lower likelihood of retreatment initiation (AOR 0.36; 95%CI 0.15-0.81). Treatment setting and prescriber type were not associated with retreatment initiation or outcome. Virological failure can be effectively retreated in primary care. Expanded access to simplified retreatment regimens through decentralised models may increase retreatment uptake and reduce HCV-related mortality.

Hepatitis C Virus Reinfection Following Direct-Acting Antiviral Treatment in the Prison Setting: The SToP-C Study.

BACKGROUND: Injection drug use (IDU) following treatment for hepatitis C virus (HCV) infection may lead to reinfection, particularly if access to harm reduction services is suboptimal. This study assessed HCV reinfection risk following direct-acting antiviral therapy within Australian prisons that had opioid agonist therapy (OAT) programs but did not have needle and syringe programs (NSPs). METHODS: The Surveillance and Treatment of Prisoners With Hepatitis C (SToP-C) study enrolled people incarcerated in 4 prisons between 2014 and 2019. Participants treated for HCV were followed every 3-6 months to identify reinfection (confirmed by sequencing). Reinfection incidence and associated factors were evaluated. RESULTS: Among 388 participants receiving treatment, 161 had available posttreatment follow-up and were included in analysis (92% male; median age, 33 years; 67% IDU in prison; median follow-up 9 months). Among those with recent (in the past month) IDU (n = 71), 90% had receptive needle/syringe sharing. During 145 person-years (PY) of follow-up, 18 cases of reinfection were identified. Reinfection incidence was 12.5/100 PY (95% confidence interval [CI]: 7.9-19.8) overall, increasing to 28.7/100 PY (95% CI: 16.3-50.6) among those with recent IDU and needle/syringe sharing. In adjusted analysis, recent IDU with needle/syringe sharing was associated with increased reinfection risk (adjusted hazard ratio [aHR], 4.74 [95% CI: 1.33-16.80]; P = .016) and longer HCV testing interval with decreased risk (ie, chance of detection; aHR, 0.41 per each month increase [95% CI: .26-.64]; P < .001). CONCLUSIONS: A high rate of HCV reinfection was observed within prison. Posttreatment surveillance and retreatment are -essential to limit the impact of reinfection. High-coverage OAT and NSPs should be considered within prisons. CLINICAL TRIALS REGISTRATION: NCT02064049.

High Effectiveness of Broad Access Direct-Acting Antiviral Therapy for Hepatitis C in an Australian Real-World Cohort: The REACH-C Study.

Australia was one of the first countries with unrestricted access to government subsidized direct-acting antiviral (DAA) therapy for adults with chronic hepatitis C virus. This study assessed real-world DAA treatment outcomes across a diverse range of Australian clinical services and evaluated factors associated with successful treatment and loss to follow-up. Real-world Effectiveness of Antiviral therapy in Chronic Hepatitis C (REACH-C) consisted a national observational cohort of 96 clinical services including specialist clinics and less traditional settings such as general practice. Data were obtained on consecutive individuals who commenced DAAs from March 2016 to June 2019. Effectiveness was assessed by sustained virological response ≥12 weeks following treatment (SVR) using intention-to-treat (ITT) and per-protocol (PP) analyses. Within REACH-C, 10,843 individuals initiated DAAs (male 69%; ≥50 years 52%; cirrhosis 22%). SVR data were available in 85% (9,174 of 10,843). SVR was 81% (8,750 of 10,843) by ITT and 95% (8,750 of 9,174) by PP. High SVR (≥92%) was observed across all service types and participant characteristics. Male gender (adjusted odds ratio [aOR] 0.56, 95% confidence interval [CI] 0.43-0.72), cirrhosis (aOR 0.52, 95% CI 0.41-0.64), recent injecting drug use (IDU; aOR 0.64, 95% CI 0.46-0.91) and previous DAA treatment (aOR 0.50, 95% CI 0.28-0.90) decreased the likelihood of achieving SVR. Multiple factors modified the likelihood of loss to follow-up including IDU ± opioid agonist therapy (OAT; IDU only: aOR 1.75, 95% CI 1.44-2.11; IDU + OAT: aOR 1.39, 95% CI 1.11-1.74; OAT only, aOR 1.36; 95% CI 1.13-1.68) and age (aOR 0.97, 95% CI 0.97-0.98). Conclusion: Treatment response was high in a diverse population and through a broad range of services following universal access to DAA therapy. Loss to follow-up presents a real-world challenge. Younger people who inject drugs were more likely to disengage from care, requiring innovative strategies to retain them in follow-up.

Effectiveness of treatment for hepatitis C virus reinfection following direct acting antiviral therapy in the REACH-C cohort.

BACKGROUND: Direct acting antiviral (DAA) therapy is highly effective for hepatitis C virus (HCV) infection, but reinfection following treatment may compromise benefits of cure. This study assessed the real-world effectiveness of treatment for reinfection. METHODS: Real-world effectiveness of antiviral therapy in chronic hepatitis C (REACH-C) is an observational study evaluating treatment outcomes following sequential DAA initiations across 33 health services in Australia between March 2016-June 2019. Reinfection was defined by post-treatment genotype switch or HCV viraemia after sustained virologic response (SVR12). RESULTS: Of the 10,843 individuals initiating DAA therapy post-treatment viraemia was reported in 526 of whom 99 were reinfections. Treatment for reinfection occurred in 88 individuals. In those with available treatment outcomes, SVR12 was similar to initial treatment in the overall REACH-C cohort (95% vs 95%; p = 0.745) and comparable across primary, tertiary, and prison settings. Classifying unknown treatment outcomes as failures, SVR12 for treatment of reinfection was lower than initial treatment in REACH-C (67% vs 81%; p = 0.002), due to higher lost to follow-up. CONCLUSIONS: Treatment of reinfection is highly effective and can be delivered in non-specialist settings. Access to treatment for reinfection in high-risk populations is crucial to HCV elimination.