Illness perceptions and treatment outcomes in Hepatitis C

Hepatitis C (HCV) is a high prevalence blood borne disease, often chronic in nature that can potentially be associated with a number of physical comorbidities such as cirrhosis of the liver, hepatocellular carcinoma, musculoskeletal pain, and cognitive impairment (Barkhuizen et al., 1999; Chen & Morgan, 2006; Forton, Taylor-Robinson, & Thomas, 2003; Glacken, Coates, Kernohan, & Hegarty, 2003; Hoofnagle, 1997; Koziel, 2005; Lehman & Cheung, 2002; Mendez et al., 2001; Ramalho, 2003), and psychological comorbidities such as depression and anxiety (Chapko et al., 2005; Chen & Morgan, 2006; Fried et al., 2002; Hauser, Zimmer, Schiedermaier, & Grandt, 2004; Lee & Harrison, 2005; Shiffman et al., 2004; Simmonds, 2001). Despite the potential for individuals to clear HCV through anti-viral treatment regimens, variance in treatment outcomes remain, and unlike other types of Hepatitis, such as Hepatitis B (HBV), no vaccine currently exists to protect individuals from contracting HCV (Coppola et al., 2004; Shiffman et al., 2004). Recent estimates suggest that approximately 170 million individuals have been infected with HCV worldwide (Lee & Abdo, 2003; Shiffman et al., 2004). Due to data collection limitations, the exact number of individuals infected with HCV in New Zealand remains unknown. Despite these limitations that are largely related to many cases of HCV remaining undiagnosed, it has been estimated that in New Zealand, approximately 54,000 individuals are currently living with HCV (Gane et al., 2014). This is compared to Australia, where it has been estimated that approximately 270,000 individuals are living with chronic cases of HCV (Gane et al., 2014). Further, estimates of HCV prevalence in New Zealand related to ethnicity have suggested that the vast majority of reported cases of HCV come from individuals from a European background (approximately 76%), compared to 15% of reported cases from within the Maori population, and 1% of reported cases coming from within the Pacific Islander population (New Zealand Health Information Service, 2001). By comparison, in Australia, estimates of HCV prevalence among individuals from an indigenous background have been problematic to determine due to a number of data collection limitations, including in many cases, the lack of a requirement to include reporting of ethnicity in many states and territories when reporting acute HCV infection (National Centre in HIV Epidemiology and Clinical Research, 2007). At the time data were collected for the present study, the standard treatment protocol for HCV included interferon (once weekly self-administered intramuscular injection), ribavirin (daily oral self-administered medication), and depending on pretreatment medical assessment results, an additional protease inhibitor drug (either boceprevir or telaprevir) (Jacobson et al., 2012; Shiffman et al., 2004; Thompson, 2016; Wackernah, Lou, & Park, 2011). Similar to ribarvirin, boceprevir and telaprevir require the individual to take an oral tablet on a daily basis for the required treatment period (Jacobson et al., 2012). Treatment periods for individuals undergoing interferon, ribavirin and protease inhibitor HCV treatment can be between 12 to 48 weeks depending on pre-treatment medical assessment results (e.g., cirrhosis of the liver typically requires longer treatment) (Jacobson et al., 2012; Wackernah et al., 2011). Further, for individuals preparing for interferon based HCV treatment, a comprehensive psychosocial assessment is often required, in addition to other pre-treatment bio-medical assessments, to determine the individual's psychological preparedness for HCV treatment (Thompson, 2016). The rationale for the inclusion of pre-treatment psychosocial assessments is primarily due to the potential for interferon to exacerbate existing mental health conditions, cause endogenous depression, or in rare cases psychosis. (Holmes, Thompson, & Bell, 2013; Sarkar, Sarkar, Berg, & Schaefer, 2015; Wackernah et al. …