Regimens with high cure rates in the immediate future, if these barriers to referral are not addressed, a large proportion of Nafcillin Sodium patients will never be linked to receive HCV treatment. It was unexpected that ongoing Oxysophocarpine substance abuse or neuropsychiatric disorders were positive predictors of HCV treatment referral. Ascertainment bias is the most likely explanation for this finding. Patients who were not referred for HCV therapy were less engaged in care, and the reliability of self-reported ongoing drug or alcohol abuse in this group of patients is uncertain. Similarly, there were more systematic evaluations and documentation of alcohol, drug abuse and neuropsychiatric disorders in the electronic medical records of patients who were referred for HCV therapy. This study found that the most common factor associated with non-initiation of HCV therapy was attributed to the combination of drug, alcohol abuse or neuropsychiatric disorders that also affect patient’s engagement in care; however, among patients who were referred for HCV therapy, the study findings suggest that even in a real-world challenging population, successful HCV therapy can be accomplished. While the numbers are small, almost 50% of those starting therapy attained a sustained viral response. Response rates are only expected to increase as interferon-free therapies that are highly efficacious in shorter time are approved. Emphasis needs to be placed on implementing models of care with integrated multidisciplinary treatment services for HIV and HCV, including treatment of alcohol and substance use, without stigma and discrimination. This strategy may increase the number of HIV coinfected patients linked to and retained in care who could also initiate and complete HCV curative therapy. Our study has several limitations. First, there was no information on insurance status and income level that in most health systems influences referral to HCV therapy. Our HCV coinfection clinic operates within the main HIV clinic and no additional insurance coverage is required, allowing our patients universal access to HCV therapy evaluation. Second, it could be argued that our definition of engagement in care is not the gold standard as there are other measures such as missed visits, gaps in care and visit constancy that could provide us a more comprehensive description of patient’s level of engagement in care. We, however, chose the HRSA HIV/AIDS Bureau performance measure for retention in HIV care that aligns with the updated HIV Medicine Association primary HIV care guidelines that highlight the concept of adherence to clinical care. Third, restricting the analysis of reasons for not initiating HCV therapy to only those patients who finish HCV clinical staging could be criticized. In fact, 53 of 303 patients referred for HCV therapy either never showed up for their HCV appointment or did not return after their first HCV appointment. We cannot rule out that other unmeasured factors, such as travel distance to our clinic and low HCV health literacy, may have negatively impacted HCV therapy initiation ; however, this limitation is balanced by the strength that most patients who completed HCV clinical staging underwent a detailed characterization of common medical, social and logistical barriers that influence HCV treatment initiation in clinical practice. Finally, as with other single site studies, our results may not be generalizable due to many factors such as different funding mechanisms of health care systems in different geographic areas.