Discussion
HCV treatment willingness and intent were high in this large prospective study of people with chronic HCV infection and a history of injecting drug use assessed for HCV infection. Factors independently associated with HCV treatment willingness included non-Aboriginal ethnicity, living with a spouse or other relatives/friends and never receiving OST. Factors independently associated with HCV treatment intent included age (35–54 years), non-Aboriginal ethnicity, living with a spouse or other relatives/friends, never receiving OST and non-1 HCV genotype. High HCV treatment willingness and early treatment intent were both predictive of subsequent HCV specialist assessment and treatment uptake. These findings highlight the need for development and implementation of strategies for enhanced specialist assessment and treatment with an initial focus on people more willing to receive treatment. Strategies are needed to increase treatment willingness and intent among those less willing.
The majority of participants were definitely willing to receive HCV treatment (67%) and had plans to initiate antiviral therapy in the short-term (70%). Previous findings have similarly shown high levels of HCV treatment willingness (53–86%) among cohorts of PWID.In one of the earlier studies, 53% of PWID were willing to receive an HCV treatment regimen which had very low efficacy (20%)and required a liver biopsy. Higher levels of HCV treatment willingness and intent in the current study are therefore unsurprising, given that liver biopsy is no longer required for treatment in Australia and current antiviral regimes have higher efficacy (50–90%).
More than half of participants in the ETHOS study (53%) were assessed by an HCV specialist and 27% initiated antiviral therapy. In adjusted analyses, high HCV treatment willingness increased the odds of specialist assessment and treatment uptake by three and four fold, respectively. Notably, early HCV treatment intent increased the odds of specialist assessment and treatment uptake by four and ten fold, respectively. Continuing attention to factors associated with HCV treatment willingness and intent, is required to enhance HCV care among those less willing to receive antiviral therapy.
In adjusted analysis, several demographic, behavioural and clinical factors were independently associated with high HCV treatment willingness and early treatment intent. Older age (35–45 vs. 18–35 years) was found to be associated with early HCV treatment intent. It has been suggested that the risk of developing HCV-related complications increases with age. Given than the mean age at first injecting drug use among ETHOS participants was 19 years, older PWID may be more likely to have more progressive liver disease or have witnessed others with HCV-related ill-health, and therefore more driven to consider HCV treatment uptake in the short-term.
Aboriginal participants were less likely to have high treatment willingness and early treatment intent. In the US, black ethnicity has been shown to be associated with lower HCV treatment uptake. In Australia, access to HCV testing is similar between Aboriginal and non-Aboriginals. However, compared to non-Aboriginal Australians, it has been demonstrated that Aboriginal people have lower levels of health education and limited access to culturally appropriate health programs. Similarly, these factors may contribute to lower levels of HCV treatment willingness and lack of early treatment intent among Aboriginal Australians. Further efforts are required to develop culturally appropriate programs to enhance education and knowledge about HCV infection among Australian Aboriginal people, which may be important for improving HCV treatment willingness and intent.
Living with a spouse or other relatives/friends was associated with high HCV treatment willingness and early treatment intent. Social support has been shown to be associated with HCV assessment. As an indicator of greater social support, living with family and/or friends may contribute to a patients' readiness to consider HCV treatment and engage with HCV care services.
High HCV treatment willingness and early treatment intent were associated with not having a history of OST. Compared to ETHOS participants who were currently receiving OST, those with no history of OST appeared to be older, less drug dependent and less marginalized. Previous findings suggest that people with HCV infection are more willing to receive antiviral therapy if they are in stable drug dependence treatment programs, not currently enrolled in drug treatment or considering quitting drug use receiving detoxification treatment and not currently injecting drugs. Participants' reports of lower willingness may reflect their concerns about the tolerability of current HCV treatment regimens, given their social and drug use situations. Treatment programs are required to provide support for complex needs of those who are less willing to receive HCV treatment and appear less suitable for antiviral therapy.
HCV genotype 1 was found to be associated with lack of early HCV treatment intent, compared with other genotypes (predominantly genotypes 2/3). HCV genotype 1 is associated with lower sustained virological response among patients receiving interferon-based therapy. Given the limited access to HCV genotype 1 triple therapy (including telaprevir or boceprevir) during the study period, ongoing evaluation of the impact of HCV genotype on treatment intent will be of great interest as direct-acting antiviral (DAA) therapy becomes more broadly available (telaprevir and boceprevir were approved for Australian government subsidization from April 2013).
There are a number of limitations of this study. Given the recruitment methodology and that all participants were assessed by a nurse or general practitioner at enrolment, the study population may represent a group that is more engaged in health services, leading to an overestimation of proportions with HCV treatment willingness and intent. Similarly, the proportions receiving HCV specialist assessment and treatment might not reflect those in populations that are not connected with health services. Furthermore, these findings may not be generalizable to other populations of people with HCV infection, particularly those less engaged in health services.
A multidisciplinary approach has been the core of many successful models delivering HCV care services to drug-using populations. Given that many clinics in the current study had limited prior expertise with specialised HCV care, provision of HCV nursing and specialist support within the existing infrastructure for addiction treatment has produced encouraging results. Improved engagement of marginalized populations with HCV care services has broadened our understanding of the role of treatment willingness on subsequent HCV specialist assessment and treatment uptake. While new interferon-free regimes are anticipated to remove many barriers to HCV care services, evidence-based and sustainable strategies are required to further engage those willing to receive antiviral therapy and develop programs to support those less willing to receive therapy.