516 Higgs P et al. disorder and those without (62, 63). One study found no difference in end of treatment response or SVR between patients with a history of mental health issues and/or drug use and those patients without (64) Notably, 8 of 10 studies listed above involved fewer than 100 individuals, and many studies did not perform multivariate analysis (56, 58-64), were conducted retrospectively (56, 60, 63, 64), and/or had various exclusion criteria relating to ongoing or uncontrolled psychiatric illness (58, 59, 63, 64). Multiple studies have found an association between a lifetime history of depression, or high depression scores at baseline, and development of depression during HCV treatment (57, 59, 64-67). One study found no difference in the symptoms of depression, schizophrenia, or mania between those with and without schizophrenia at baseline (68). Similarly, no difference was found in the development of symptoms during treatment when a group of patients with various psychiatric disorders was compared to a group of patients without any psychiatric disorders (69) or when a group of patients with a history of psychiatric disorders and/ or illicit drug use was compared to a group of patients without any of these (63). However, similar to the studies investigating the relationship between pre-existing mental health problems and treatment outcomes, 8 of 11 studies involved fewer than 100 participants, and 2 studies were conducted retrospectively (60, 64). 4.3.1. Implications Although, there is some evidence to suggest that having a history of depression or a high depression score when commencing treatment increases the likelihood of an individual developing depression during HCV treatment and potentially affecting treatment completion, there is no evidence to suggest that a pre-existing psychiatric disorder could adversely affect the likelihood of attaining an end-of-treatment response or SVR. Evidence also suggests that people experience a number of side effects from their HCV treatment. These results suggest that rather than automatically excluding individuals with pre-existing psychiatric disorders from treatment, they should receive appropriate care for their psychiatric disorder before, during, and after HCV treatment. 5. Conclusion In most developing countries, formal policies restricting PWID from accessing HCV treatment have been lifted over the past 10 years. Although some PWID now receive treatment, the rates remain low; many PWID are still being excluded from treatment because of concerns about their continuous alcohol consumption, injecting drug use, and pre-existing mental illness. Our review highlights the lack of evidence supporting these exclusions. Many of the studies that we reviewed included only a small number of participants and failed to adjust their findings to account for potential ambiguity. Our Intravenous drug users and hepatitis C treatment evidence suggests that a patient’s likelihood of attaining SVR is impacted more by the adherence to treatment than by the frequency of drug injecting during the treatment period. Likewise, although there is evidences showing that a pre-existing mental illness may increase the likelihood of experiencing depression as a side effect of the treatment, from our review, it appears that the patients with pre-existing mental illnesses who complete the treatment are just as likely as other patients to attain SVR; this highlights the role of concurrent management of mental health problems with HCV treatment. To ensure that alcohol consumption does not have a direct effect on treatment efficacy, continued counseling should be offered to patients on reducing their alcohol consumption before and during treatment. However, as some patients have successfully completed treatment even while continuing to consume moderate amounts of alcohol, alcohol consumption should not be seen as an automatic exclusion criterion for HCV treatment. The decision to treat HCV should be patient centered and made on a case-by-case basis with foremost attention to the needs and interests of the person seeking treatment. The research in this area is ongoing, and as the number of studies increases, we will be able to pool more data on a range of indicators, which may help understand the factor that has the greatest impact on the HCV treatment outcome. At present, there is no compelling evidence for restricting access to PWID seeking HCV treatment. We consider this the right time for making evidence-based decisions rather than making decisions based on pre- conceived ideas about patients who deserve treatment for HCV, and we hope that those involved in deciding to offer HCV treatment would consider the results of our study. Financial support None declared. Conflict of interest None declared. References 1. Aceijas C, Rhodes T. Global estimates of prevalence of HCV infection among injecting drug users. Int J Drug Policy. 2007;18(5):352-8. 2. Te HS, Jensen DM. Epidemiology of hepatitis B and C viruses: a global overview. Clin Liver Dis. 2010;14(1):1-21. 3. Edlin BR. Hepatitis C prevention and treatment for substance users in the United States: acknowledging the elephant in the living room. Int J Drug Policy. 2004;15(2):81-91. 4. Mehta S, Genberg B, Astemborski J, Kavasery R, Kirk G, Vlahov D, et al. Limited Uptake of Hepatitis C Treatment Among Injection Drug Users. J Community Health. 2008;33(3):126-33. 5. Kresina TF, Khalsa J, Cesari H, Francis H. Hepatitis C virus infection and substance abuse: medical management and developing models of integrated care--an introduction. Clin Infect Dis. 2005;40(Suppl 5):S259-62. 6. Hellard M, Sacks-Davis R, Gold J. Hepatitis C treatment for injection drug users: a review of the available evidence. Clin Hepat Mon. 2011;11(7):513-518