Facilitating engagement of persons with opioid use disorder in treatment for hepatitis C virus infection via telemedicine: Stories of onsite case managers.

Although hepatitis C virus (HCV) infection has high prevalence and incidence in persons with opioid use disorder (PWOUD), their engagement in HCV care has been limited due to a variety of factors. In an ongoing multisite study at 12 opioid treatment programs (OTPs) throughout New York State (NYS), we have been evaluating telemedicine accompanied by onsite administration of direct acting antiviral (DAA) medications compared with usual care including offsite referral to a liver specialist for HCV management. Each site has a case manager (CM) who is responsible for all study-related activities including participant recruitment, facilitating telemedicine interactions, retention in care, and data collection. Our overall objective is to analyze CM experiences of clients' stories and events to understand how the telemedicine model facilitates HCV treatment. Hermeneutic phenomenology was used to interpret and to explicate common meanings and shared practices of the phenomena of case management, and a focus group with CMs was conducted to reinforce and expand on key themes identified from the CMs' stories. We identified three themes: (1) building trust, (2) identification of multiple competing priorities, and (3) development of personalized care approaches. Our results illustrate that trust is a fundamental pillar on which the telemedicine system can be based. Participants' experiences at the OTP can reinforce trust. Understanding the specific competing priorities and routinizing dedicated personalized approaches to overcome them are key to increasing participation in HCV care among PWOUD.

A framework for patient-centered telemedicine: Application and lessons learned from vulnerable populations.

Virtual technologies can facilitate clinical monitoring, clinician-patient interactions, and enhance patient-centered approaches to healthcare delivery. Telemedicine, two-way communication between a healthcare provider and a patient not in the same physical location, emphasizes patient preference and convenience by substituting the transportation of patients with information transfer. We present a framework for implementation of a comprehensive, dynamic, patient-centered telemedicine network deployed in 12 opioid treatment programs (OTP) located throughout New York State (NYS). The program aims to effectively manage hepatitis C virus (HCV) infection via telemedicine with co-administration of HCV and substance use medications. We have found that the Sociotechnical System model with emphasis on patient-centered factors provides a framework for telemedicine deployment and implementation to a vulnerable population. The issue of interoperability between the telemedicine platform and the electronic health record (EHR) system as well as clinical information retrieval for medical decision-making are challenges with implementation of a comprehensive, dynamic telemedicine system. Targeting telemedicine to a vulnerable population requires additional consideration of trust in the security and confidentiality of the telemedicine system. Our contribution is the valuable lessons learned from implementing a comprehensive, dynamic, patient-centered telemedicine system among an OTP network throughout NYS as applied to a vulnerable population that can be generalized to other difficult-to-reach populations.

Genetic Variation at IFNL4 Influences Extrahepatic Interferon-Stimulated Gene Expression in Chronic HCV Patients.

Polymorphisms at IFNL4 strongly influence spontaneous resolution and interferon therapeutic response in hepatitis C virus (HCV) infection. In chronic HCV, unfavorable alleles are associated with elevated interferon (IFN)-stimulated gene (ISG) expression in the liver, but extrahepatic effects are less well characterized. We used RNA sequencing (RNA-Seq) to examine whether IFNL4 genetic variation (rs368234815) modulates ISG expression in peripheral blood mononuclear cells (PBMC) during chronic HCV infection. ISG expression was elevated in unstimulated PBMC homozygous for the unfavorable ΔG IFNL4 variant; expression following IFN-α stimulation was comparable across genotypes. These findings suggest that lambda interferons may have broader systemic effects during HCV infection.

Hepatitis C virus core antigen: A potential alternative to HCV RNA testing among persons with substance use disorders.

BACKGROUND: The hepatitis C virus (HCV) core antigen (HCVcAg) may be an alternative diagnostic method to HCV RNA especially in populations such as substance users, the homeless or in resource-limited settings. AIMS: To evaluate performance of HCVcAg test in patients with opioid use disorder (OUD) on methadone in order to document its performance characteristics in the target population and to ensure that its specificity remains consistent across different populations. METHODS: HCVcAg levels from 109 methadone-maintained patients were compared to HCV RNA levels. RESULTS: Mean age was 53.8±7.8years, 59.6% were male, 68.8% African American, and 44% HCV-infected. HCVcAg was detectable in 47 of 48 HCV-infected, and undetectable in all HCV RNA negative patients. The HCVcAg assay had sensitivity of 97.9% and specificity of 100%. Correlation with HCV RNA levels was excellent (r=0.88, 95% CI 0.76; 0.95, p<0.01). CONCLUSION: HCVcAg has excellent performance for the diagnosis of HCV infection in patients with OUD on methadone.

Liver Disease and Fibrosis Assessment in Substance Use-Related Disorders.

Substance users have the highest prevalence of hepatitis C virus (HCV) infection but have rarely been treated, largely because of their mistrust of the health care system, misconceptions about the consequences of the infection, and concerns regarding interferon-related side effects. With the development of highly efficacious, interferon-free therapeutic regimens without significant side effects, the concept of colocating HCV and substance use treatment would appear to be highly feasible. This process has been further facilitated by widespread clinical adaptation of noninvasive assays for fibrosis assessment, which could be performed routinely in substance use treatment facilities. The most commonly used noninvasive fibrosis assessment methods are serum marker indexes and transient elastography, both of which are very accurate in detecting cirrhosis or the absence of fibrosis, but much less successful in identifying intermediate fibrosis stages. The effect of drugs of abuse on the liver is not completely understood or sufficiently studied. There are no indications that heroin and cocaine affect fibrosis progression, but some recreational drugs (eg, alcohol and cannabis) can induce hepatic injury. In addition, knowledge gaps exist on the effect of impaired liver function on metabolism or transport of agents used to treat substance disorders as well as their interactions with HCV antivirals.

Fibrosis Progression in Patients With Chronic Hepatitis C Virus Infection.

BACKGROUND: Fibrosis progression varies markedly in hepatitis C virus (HCV)-infected individuals. We investigated factors that influence fibrosis progression in chronic HCV infection. METHODS: HCV-infected patients who underwent at least 2 liver biopsies were included in this study. Associations between fibrosis progression and epidemiologic, virologic, and disease-associated factors were analyzed using logistic regression and multistate Markov modeling. RESULTS: We analyzed 936 biopsy specimens obtained from 378 individuals. Mean age (±SD) at first biopsy was 48.3 ± 9.3 years, 59.3% of patients were male, 59.9% were white, and 86.7% were infected with HCV genotype 1. Fibrosis progression and cirrhosis occurred in 57.4% and 5.8%, respectively. Fibrosis progression between the first and last biopsies was associated with lower fibrosis in the first biopsy specimen (P < .001) and with the occurrence of at least 1 flare in the alanine aminotransferase (ALT) level (>200 U/L; P = .007). We found the highest fibrosis progression rate between stages 0 and 1 and the lowest between stages 2 and 3. Increased necroinflammation and higher ALT level were associated with faster progression. HCV genotype 3-infected patients were more likely to progress to cirrhosis (P < .001). CONCLUSIONS: Fibrosis progression in HCV is not linear but varies according to stage, with the highest progression in patients with the lowest fibrosis severity. Patients who experience flares in the ALT level are also more likely to progress.

Improvements in HCV-related Knowledge Among Substance Users on Opioid Agonist Therapy After an Educational Intervention.

OBJECTIVES: Lack of knowledge about hepatitis C virus (HCV) is a principal barrier to substance users' engagement into care for the infection. As a step toward their increased engagement into HCV care, the objective of this study was to deliver an HCV-related educational intervention to substance users on opioid agonist therapy and to assess the change in HCV-related knowledge after the intervention. METHODS: We designed a comprehensive and interactive hepatitis C-related educational intervention, composed of two 30 to 60-minute sessions conducted during 2 consecutive weeks. Patients' knowledge about hepatitis C was assessed immediately before and after the intervention using a 7-item questionnaire. RESULTS: A total of 110 patients completed both educational sessions. Patients' mean age was 54.7 ±â€Š7.8 years, 58.7% were men, 70.4% African American, and 30% were Hispanic. We observed a significant increase in HCV-related knowledge after completion of the educational intervention. Whereas 65.45% of patients answered 5 or more questions correctly before the intervention, 83.64% had 5 or more questions answered correctly on the posteducational quiz (P < 0.001). Male sex, ever receiving an HCV diagnostic test before the educational intervention, and a higher level of HCV knowledge on the preeducational quiz were found to be significantly associated with HCV-related knowledge after the educational intervention. CONCLUSIONS: Patients' knowledge about hepatitis C was found to be significantly improved after the educational intervention. Therefore, HCV-related education could be the first step toward effective enrollment of patients on opioid agonist therapy into hepatitis C care.

IFN-α-Induced Downregulation of miR-221 in Dendritic Cells: Implications for HCV Pathogenesis and Treatment.

Although interferon (IFN)-α is known to exert immunomodulatory and antiproliferative effects on dendritic cells (DCs) through induction of protein-coding IFN-stimulated genes (ISGs), little is known about IFN-α-regulated miRNAs in DCs. Since several miRNAs are involved in regulating DC functions, it is important to investigate whether IFN-α's effects on DCs are mediated through miRNAs as well. In this study, we examined miRNA expression patterns in myeloid DCs (mDCs) and plasmacytoid DCs after exposing them to IFN-α. We report that IFN-α downregulates miR-221 in both DC subsets via inhibition of STAT3. We validated proapoptotic proteins BCL2L11 and CDKN1C as miR-221 targets suggesting that IFN-α can induce DC apoptosis via miR-221 downregulation. In addition, we validated another miR-221 target, SOCS1, which is known to be a negative regulator of JAK/STAT signaling. Consistent with this, miR-221 overexpression in mDCs enhanced the secretion of proinflammatory cytokines IL-6 and TNF-α. In peripheral blood mononuclear cells (PBMCs) of HIV-1/HCV co-infected individuals undergoing IFN-α-based treatment the baseline miR-221 expression was lower in non-responders compared with responders; and miR-221 expression directly correlated with DC frequency and IL-6/TNF-α secretion. In addition to PBMCs, we isolated total liver cells and kupffer cells from HCV-infected individuals and individuals with alcoholic cirrhosis. We found that both total liver cells and kupffer cells from HCV-infected individuals had significantly higher miR-221 levels compared with individuals with cirrhosis. Overall, we demonstrate that IFN-α exerts both antiproliferative and immunomodulatory effects on mDCs via miR-221 downregulation; and IFN-miR-221 axis can play important role in HCV pathogenesis and treatment.

Intrahepatic and Peripheral CXCL10 Expression in Hepatitis C Virus-Infected Patients Treated With Telaprevir, Pegylated Interferon, and Ribavirin.

UNLABELLED: We assessed peripheral and liver CXCL10 levels in 15 patients treated with telaprevir/pegylated interferon/ribavirin. Induction of peripheral CXCL10 messenger RNA (mRNA) peaked (mean fold-induction [±SD], 3.1 ± 1.9) between treatment hour 6 and day 2, while induction of intrahepatic CXCL10 mRNA peaked (mean fold-induction [±SD], 1.3 ± 0.54) at hour 10 or day 4. Peripheral CXCL10 levels were higher at treatment hour 10 (P = .032) and day 2 (P = .009) in patients with undetectable virus 2 weeks after treatment initiation. Treatment hour 10 (P = .023) and peak (P = .034) intrahepatic CXCL10 levels were also higher in these patients. CXCL10 did not distinguish treatment responders from nonresponders. In conclusion, CXCL10 identified very rapid virological response in patients treated with a direct-acting antiviral. CLINICAL TRIALS REGISTRATION: NCT00892697.

FibroSURE as a noninvasive marker of liver fibrosis and inflammation in chronic hepatitis B.

BACKGROUND: Noninvasive markers of liver fibrosis have not been extensively studied in patients with chronic hepatitis B virus (HBV) infection. Our aim was to evaluate the capacity of FibroSURE, one of the two noninvasive fibrosis indices commercially available in the United States, to identify HBV infected patients with moderate to severe fibrosis. METHODS: Forty-five patients who underwent liver biopsy at a single tertiary care center were prospectively enrolled and had FibroSURE performed within an average interval of 11 days of the biopsy. RESULTS: Of the 45 patients, 40% were Asian, 40% were African American, and 13% were Caucasian; 27% were co-infected with HIV and 67% had no or mild fibrosis. We found FibroSURE to have moderate capacity to discriminate between patients with moderate to high fibrosis and those with no to mild fibrosis (area under receiver operating characteristic [AUROC] curve = 0.77; 95% confidence interval [CI] [0.61, 0.92]). When we combined the fibrosis score determined by FibroSURE with aspartate aminotransferase (AST) measurements and HIV co-infection status, the discriminatory ability significantly improved reaching an AUROC of 0.90 (95% CI [0.80, 1.00]). FibroSURE also had a good ability to differentiate patients with no or mild from those with moderate to high inflammation (AUROC = 0.83; 95% CI [0.71, 0.95]). CONCLUSIONS: FibroSURE in combination with AST levels has an excellent capacity to identify moderate to high fibrosis stages in chronic HBV-infected patients. These data suggest that FibroSURE may be a useful substitute for liver biopsy in chronic HBV infection.

Telaprevir-based treatment effects on hepatitis C virus in liver and blood.

UNLABELLED: Understanding hepatitis C virus (HCV) replication has been limited by access to serial samples of liver, the primary site of viral replication. Our understanding of how HCV replicates and develops drug-resistant variants in the liver is limited. We studied 15 patients chronically infected with genotype 1 HCV treated with telaprevir (TVR)/pegylated-interferon alpha/ribavirin. Hepatic fine needle aspiration was performed before treatment and at hour 10, days 4 and 15, and week 8 after initiation of antiviral therapy. We measured viral kinetics, resistance patterns, TVR concentrations, and host transcription profiles. All patients completed all protocol-defined procedures that were generally well tolerated. First-phase HCV decline (baseline/treatment day 4) was significantly slower in liver than in plasma (slope plasma: -0.29; liver, -0.009; P < 0.001), whereas second-phase decline (posttreatment days 4-15) did not differ between the two body compartments (-0.11 and -0.15, respectively; P = 0.1). TVR-resistant variants were detected in plasma, but not in liver (where only wild-type virus was detected). Based upon nonstructural protein 3 sequence analysis, no compartmentalization of viral populations was observed between plasma and liver compartments. Gene expression profiling revealed strong tissue-specific expression signatures. Human intrahepatic TVR concentration, measured for the first time, was lower, compared to plasma, on a gram per milliliter basis. We found moderate heterogeneity between HCV RNA levels from different intrahepatic sites, indicating differences in hepatic microenvironments. CONCLUSION: These data support an integrated model for HCV replication wherein the host hepatic milieu and innate immunity control the level of viral replication, and the early antiviral response observed in the plasma is predominantly driven by inhibition of hepatic high-level HCV replication sites.

Hepatitis C virus-related knowledge and willingness to receive treatment among patients on methadone maintenance.

OBJECTIVES: Although persons who inject drugs have high prevalence of hepatitis C virus (HCV) infection, few receive treatment mostly because of lack of knowledge about the infection and its treatment. We assessed the level of HCV-related knowledge and willingness to participate in HCV treatment among methadone-maintained patients. METHODS: A 30-item survey covering HCV-related knowledge and willingness to engage in HCV-related education and treatment was developed and completed by 320 methadone-maintained patients. RESULTS: Respondents' mean age was 53 ± 8.7 years, 59.5% were male, 55.1% were African American, and 38.3% were Hispanic. The mean duration of methadone maintenance was 7 ± 6.7 years. In the preceding 6 months, 6.9% of patients reported injection drug use, whereas 37.3% used noninjection drugs. Hepatitis C virus seropositivity was self-reported by 46.3% of patients. The majority of patients (78%) expressed willingness to participate in HCV-related education and to receive HCV treatment. Most patients (54.7%) correctly answered 5 or more of 7 questions assessing HCV knowledge. Hepatitis C virus-seropositive individuals and prior attendees at HCV-related educational activities demonstrated a higher level of HCV-related knowledge (P < 0.001 and P = 0.002, respectively). Younger patients (P = 0.014), those willing to attend an HCV-related educational activity (P < 0.001), and those with higher-HCV-related knowledge (P = 0.029) were more accepting of HCV treatment. Fear of medication-related side effects was the most common reason for treatment avoidance. CONCLUSIONS: The majority of patients reported willingness to receive HCV-related education and treatment. Treatment willingness was significantly associated with previous attendance at an HCV educational activity and a higher level of HCV-related knowledge.

Host Genetic Factors and Dendritic Cell Responses Associated with the Outcome of Interferon/Ribavirin Treatment in HIV-1/HCV Co-Infected Individuals.

HIV-1/HCV co-infection is a significant health problem. Highly active antiretroviral treatment (HAART) against HIV-1 has proved to be fairly successful. On the other hand, direct acting antiviral drugs against HCV have improved cure rates but high cost and development of drug resistance are important concerns. Therefore PEGylated interferon (PEG-IFN) and ribavirin (RBV) still remain essential components of HCV treatment, and identification of host factors that predict IFN/RBV treatment response is necessary for effective clinical management of HCV infection. Impaired dendritic cell (DC) and T cell responses are associated with HCV persistence. It has been shown that IFN/RBV treatment enhances HCV-specific T cell functions and it is likely that functional restoration of DCs is the underlying cause. To test this hypothesis, we utilized an antibody cocktail (consisting of DC maturation, adhesion and other surface markers) to perform comprehensive phenotypic characterization of myeloid DCs (mDCs) and plasmacytoid DCs (pDCs) in a cohort of HIV-1/HCV co-infected individuals undergoing IFN/RBV treatment. Our results show that pre-treatment frequencies of mDCs are lower in non-responders (NRs) compared to responders (SVRs) and healthy controls. Although, the treatment was able to restore the frequency of mDCs in NRs, it downregulated the frequency of CCR7+, CD54+ and CD62L+ mDCs. Pre-treatment frequencies of pDCs were lower in NRs and decreased further upon treatment. Compared to SVRs, NRs exhibited higher ratio of PD-L1+/CD86+ pDCs prior to treatment; and this ratio remained high even after treatment. These findings demonstrate that enumeration and phenotypic assessment of DCs before/during therapy can help predict the treatment outcome. We also show that before treatment, PBMCs from SVRs secrete higher amounts of IFN-γ compared to controls and NRs. Upon genotyping IFNL3 polymorphisms rs12979860, rs4803217 and ss469415590, we found rs12979860 to be a better predictor of treatment outcome. Collectively, our study led to identification of important correlates of IFN/RBV treatment response in HIV-1/HCV co-infected individuals.

Hepatitis C virus control among persons who inject drugs requires overcoming barriers to care.

Despite a high prevalence of hepatitis C virus (HCV) infection, the vast majority of persons who inject drugs (PWID) have not engaged in HCV care due to a large number of obstacles. Education about the infection among both PWID and providers remains an important challenge as does discrimination faced by PWID in conventional health care settings. Many providers also remain hesitant to prescribe antiviral therapy due to concerns about adherence and relapse to drug use resulting in reinfection. Presently, however, as a result of improvements in treatment efficacy combined with professional society and government endorsement of HCV treatment for PWID, a pressing need exists to develop strategies to engage these individuals into HCV care. In this article, we propose several strategies that can be pursued in an attempt to engage PWID into HCV management. We advocate that multidisciplinary approaches that utilize health care practitioners from a wide range of specialties, as well as co-localization of medical services, are strategies likely to result in increased numbers of PWID entering into HCV management. Pursuit of HCV therapy after stabilization through drug treatment is an additional strategy likely to increase PWID engagement into HCV care. The full impact of direct acting antivirals for HCV will only be realized if innovative approaches are pursued to engage all HCV infected individuals into treatment.

Persistence of hepatitis C virus during and after otherwise clinically successful treatment of chronic hepatitis C with standard pegylated interferon α-2b and ribavirin therapy.

Resolution of chronic hepatitis C is considered when serum HCV RNA becomes repeatedly undetectable and liver enzymes normalize. However, long-term persistence of HCV following therapy with pegylated interferon-α/ribavirin (PegIFN/R) was reported when more sensitive assays and testing of serial plasma, lymphoid cells (PBMC) and/or liver biopsies was applied. Our aim was to reassess plasma and PBMCs collected during and after standard PegIFN/R therapy from individuals who became HCV RNA nonreactive by clinical testing. Of particular interest was to determine if HCV genome and its replication remain detectable during ongoing treatment with PegIFN/R when evaluated by more sensitive detection approaches. Plasma acquired before (n = 11), during (n = 25) and up to 12-88 weeks post-treatment (n = 20) from 9 patients and PBMC (n = 23) from 3 of them were reanalyzed for HCV RNA with sensitivity <2 IU/mL. Clone sequencing of the HCV 5'-untranslated region from plasma and PBMCs was done in 2 patients. HCV RNA was detected in 17/25 (68%) plasma and 8/10 (80%) PBMC samples collected from 8 of 9 patients during therapy, although only 5.4% plasma samples were positive by clinical assays. Among post-treatment HCV RNA-negative plasma samples, 9 of 20 (45.3%) were HCV reactive for up to 59 weeks post-treatment. Molecularly evident replication was found in 6/12 (50%) among PBMC reactive for virus RNA positive strand collected during or after treatment. Pre-treatment point mutations persisted in plasma and/or PBMC throughout therapy and follow-up. Therefore, HCV is not completely cleared during ongoing administration of PegIFN/R otherwise capable of ceasing progression of CHC and virus commonly persists at levels not detectable by the current clinical testing. The findings suggest the need for continued evaluation even after patients achieve undetectable HCV RNA post-treatment.

IL28B polymorphism, pretreatment CXCL10, and HCV RNA levels predict treatment response in racially diverse HIV/HCV coinfected and HCV monoinfected patients.

OBJECTIVE: We sought to develop a score to predict sustained virological response (SVR) in racially diverse HIV/hepatitis C virus (HCV)-coinfected and HCV-monoinfected pegylated interferon/ribavirin-treated patients. METHODS: We retrospectively evaluated 374 patients (259 monoinfected and 115 coinfected) treated at a single tertiary care center. The IL28B rs12979860 single nucleotide polymorphism genotyping was performed in 335 patients, and plasma CXCL10 levels were measured by enzyme-linked immunosorbent assay in 171 patients. RESULTS: Of the 374 patients, 64.9% were white, 17.2% were African American, 76.5% were HCV genotype 1 infected, and 49.3% had advanced fibrosis. Sustained virological response was achieved by 151 (40.4%) patients, 106 (40.9%) patients monoinfected, and 45 (39.1%) patients coinfected. Patients with IL28B C/C genotype were significantly more likely to achieve an SVR compared with non-C/C genotype patients, but only if they were infected with HCV genotypes 1/4 (59.1% vs 21.1%, P < 0.0001). No significant differences existed in IL28B predictive capacity between coinfected and monoinfected patients. Pretreatment CXCL10 levels were significantly higher in nonresponders, both monoinfected and coinfected, compared with SVR patients (P = 0.0018). Coinfected patients had higher CXCL10 levels compared with monoinfected patients (P = 0.03). The combination of IL28B genotype, pretreatment CXCL10 and HCV RNA levels, and HCV genotype had the best ability to predict treatment response in both patient groups (area under the receiver operating characteristic curve = 0.85). Among all patients, a cutoff score of -0.94 or more had a sensitivity of 0.93 and specificity of 0.59. In coinfected patients, a score of -0.55 or more had sensitivity of 0.81 and specificity of 0.80. CONCLUSIONS: IL28B genotype, pretreatment CXCL10, and HCV RNA levels have very good capacity to predict pegylated interferon/ribavirin-treatment outcome in both HIV/HCV coinfected and HCV monoinfected patients.

Assessment of methadone clinic staff attitudes toward hepatitis C evaluation and treatment.

We used a 25-item, self-administered questionnaire to assess staff's perceived barriers and willingness to engage in onsite treatment of hepatitis C virus (HCV) at the Beth Israel Medical Center methadone maintenance treatment program (MMTP) at its Harlem sites. Of 80 participants, 50% were counselors and 24% were directly involved in referral or HCV testing. Although 92% of the MMTP staff indicated that they discuss HCV evaluation and treatment with patients at least annually, 70% believed that less than 25% of patients accept referral for HCV treatment and attend their initial appointment. Most staff (66%) supported onsite HCV evaluation and treatment, although support was higher among those with a bachelor's degree or higher (p = 0.046). Lack of infrastructure was perceived as the greatest obstacle to onsite treatment. Educational interventions and skill building for staff to confidently engage and support MMTP patients in HCV treatment may be necessary prerequisites for onsite HCV management in MMTPs.

Determinants of hepatitis C virus treatment completion and efficacy in drug users assessed by meta-analysis.

BACKGROUND: Hepatitis C virus (HCV)-infected drug users (DUs) have largely been excluded from HCV care. We conducted a systematic review and meta-analysis of the literature on treatment completion and sustained virologic response (SVR) rates in DUs. We assessed the effects of different treatment approaches and services to promote HCV care among DUs as well as demographic and viral characteristics. METHODS: Studies of at least 10 DUs treated with pegylated interferon/ribavirin that reported SVR were analyzed. Heterogeneity was assessed (Cochran test) and investigated (meta-regression), and pooled rates were estimated (random effects). RESULTS: Thirty-six studies comprising 2866 patients were retrieved. The treatment completion rate among DUs was 83.4% (95% confidence interval [CI], 77.1%-88.9%). Among studies that included addiction-treated and untreated patients during HCV therapy, the higher the proportion of addiction-treated patients, the higher the HCV treatment completion rate (P < .0001). After adjusting for human immunodeficiency virus (HIV)/HCV coinfection, sex, and treatment of addiction, support services during antiviral therapy increased treatment completion (P < .0001). The pooled SVR rate was 55.5% (95% CI, 50.6%-60.3%). Genotype 1/4 (P = .0012) and the proportion of HIV-coinfected DUs (P = .0173) influenced the SVR rate. After adjusting for HCV genotype 1/4 and HIV/HCV coinfection, the SVR rate was positively correlated with involvement of a multidisciplinary team (P < .0001). CONCLUSIONS: Treatment of addiction during HCV therapy results in higher treatment completion. Our pooled SVR rate is similar to that obtained in registration trials in the general population. Treatment of addiction during HCV therapy will likely be important for HCV-infected DUs undergoing treatment with more complex regimens including direct-acting antivirals.