While current medications used to treat patients with chronic hepatitis C virus (HCV) effectively produce sustained viral response (SVR), postponement of therapy is oftentimes attributed to patient perceptions of unfavourable outcomes. However, an instrument to assess patient perceptions of therapy (i.e. treatment satisfaction) has not been developed.
To describe the development and validation the chronic Hepatitis C Virus Treatment Satisfaction (HCVTSat) instrument.
Focus groups, expert review and cognitive debriefing were used to develop a draft 37-item instrument (scale: 1 = not important at all; 5 = extremely important). The preliminary instrument was administered to a pre-test sample of 145 patients through Mayo Clinic, Rochester, MN. A refined HCVTSat was administered to a main sample of 333 participants with a chronic HCV diagnosis through Harris Interactive.
The HCVTSat was completed by 333 participants with an average age of 51 (s.d. = 12.1) years, 55% male, current or previous HCV treatment experience, and a diagnosis of HCV for approximately 12 (s.d. = 8.9) years. Twelve items for the 3 dimensions, Treatment Experience (TE), Side Effects (SE) and Social Aspects (SA), were internally consistent (Cronbach's α range: 0.70–0.90), responsive and valid. Confirmatory factor analysis (goodness-of-fit indexes: χ2 = 20.9, df= 23, P =0.59; CFI = 1.00, GFI = 0.99, TFI = 1.00, RMSEA = 0.001) revealed a better fit with 9 items. All path coefficients were significant (P <0.05). SE and SA were strong predictors of TE, while TE was positively associated with the 1-item global measure of TS (path coefficient = 0.12).
The 10-item HCVTSat demonstrated valid psychometric properties and assessed patient satisfaction with HCV therapies. However, additional studies are needed to validate the HCVTSat in conjunction with SVR and in patients in underrepresented populations.
Chronic hepatitis C virus (HCV) affects more than 170 million people worldwide and is a leading cause of chronic liver disease and hepatocellular carcinoma for an estimated 3–5 million people infected with HCV throughout the United States.[1-3] While pegylated interferon alfa and ribavirin provide a foundation for chronic HCV treatment, patient response to therapy varies as a function of time from diagnosis and appears to be linked to the extent of liver fibrosis, cirrhosis and baseline risk for developing hepatocellular carcinoma. Long-term effects from HCV negatively impact patient perceptions of health; however, side effects from pegylated interferon and ribavirin therapy (including anemia, fatigue, headache, upset stomach, depression, irritability, loss of appetite, difficulty with glucose control, skin reactions and insomnia) may cause patients to postpone, avoid or stop therapy.[6-10] While the most recently approved regimens for chronic HCV that combine pegylated interferon and ribavirin with direct-acting-antiviral (DAA) agents are expected to improve patient outcomes, these agents also expose patients to risks of blood dyscrasia, rash, pruritis, depression and anxiety.[11, 12]
Considering these issues as well as other presentations (e.g. co-morbidities, alcohol, and drug abuse) frequently encountered in patients with chronic HCV, the ability to assess satisfaction with therapy could provide an opportunity to help patients overcome therapeutic challenges, reduce their reluctance to initiate and continue therapy, and improve long-term survival.[13, 14] Moreover, as the paradigm shifts from interferon containing regimens to newer, all oral, DAA regimens with potentially less side effect profiles and improved clinical efficacy, the development of an instrument to assess treatment satisfaction may provide prescribers with a decision tool to guide treatment choice and patient progress in a potentially complex treatment environment. The recent proposal by the Center for Disease Control and Prevention to mandate 1-time HCV screening for the 1945–1965 birth cohort would potentially identify significant numbers of additional patients for treatment and further emphasise the need to evaluate the acceptability of therapy
Patient-reported outcome (PRO) instruments are commonly used to understand how treatment satisfaction is influenced by patient perceptions of their experience with therapy. The focus on satisfaction with therapy is a natural evolution of previous constructs assessing satisfaction with the healthcare system, healthcare services and patient access to care. Conceptually, treatment satisfaction represents a culmination of experiences (e.g. perceptions of treatment, satisfaction with therapy) related to patient expectations, intentions to continue treatment, effectiveness, side effects and the impact of treatment at higher levels of cognitive functioning.[16-18] Besides treatment satisfaction, patient responses to other PRO measures related to health-related quality of life and patient care are commonly used to assess functional status during and following HCV therapy.[19, 20] Although treatment satisfaction has been examined in other chronic disease states,[21-24] there are no instruments available that use a psychometric approach to examine the effects of therapy on treatment satisfaction for patients with chronic HCV. In this study, we describe the development and validation of the Chronic Hepatitis C Virus Treatment Satisfaction (HCVTSat) Instrument to assess treatment satisfaction for patients with chronic HCV.
Patients and Methods
To ensure that items in the draft instrument represented the domain of treatment satisfaction, we conducted a literature review of peer-reviewed articles on the topic of chronic HCV that appeared between 1995 and 2012. Databases examined included PUBMED, SOCIAL CITATION INDEX and MEDLINE, etc. Keywords included primary health care, HCV, treatment satisfaction (TS), treatment experience (TE), satisfaction with treatment, patient-reported outcomes, treatment assessment, treatment value, treatment expectations, treatment reluctance, health-related outcomes, treatment preference and other outcomes that were pertinent to patients with chronic HCV. Items from the articles were compiled and examined by an expert panel consisting of seven individuals, including physicians, pharmacists, and researchers with expertise in study design and psychometrics to determine their relevance to the scope of the study. Throughout the initial process of instrument development, the panel of experts was instructed to review the instrument and recommend any changes to the items as deemed necessary to improve readability, comprehension and acceptability. After several discussions, consensus was reached on a final set of items to serve as the foundation for instrument development.
Input from patients with a history of HCV was obtained from two focus groups conducted at Mayo Clinic, Rochester, MN. There were a total of 15 participants; 6 in one focus group and 9 in another group. The interview process lasted more than 1 h and was facilitated by a moderator trained to elicit experiences and perceptions of living with HCV and treatment information using a thematic and evaluative approach. Focus groups were transcribed verbatim using NVivo 8 qualitative analysis software (QSR International, Cambridge, MA, USA) and assessed through inductive analysis by three independent reviewers. Discrepancies in coding were examined and discussed until consensus was reached among these analysts. The consensus coding structure was used to generate a model of focus group results conveyed by a series of categories and themes to ascertain the alignment with items selected for instrument development. After the process of thematic development was completed, experts and investigators convened one last time to discuss and resolve any discrepancies between items identified through expert opinion and items generated from the two focus groups.
Information from the focus groups was used to draft an initial instrument, which contained 37 items that were grouped into the following themes: treatment satisfaction, side effects, barriers to seeking treatment, psychological impact of HCV, benefits of treatment and stigma associated with chronic HCV. The preliminary instrument elicited information pertaining to 37 items regarding patient perceptions of each item's relational importance to TS ranging from 1 = not important at all to 5 = extremely important. In addition, overall treatment satisfaction was measured by a single item using a ten-point scale ranging from not satisfied at all to extremely satisfied. Information pertaining to health co-morbidities, demographics, ethnicity and symptom severity was also elicited.
To ensure instrument readability, evaluate reliability and collect information for later use to assess validity, the initial 37-item instrument was administered to 145 patients who were currently under the care of gastroenterologists and primary care physicians at one of two large medical centres in Rochester, MN. The instrument was either mailed to patients or administered during patient visits to the clinic. Patients visiting the clinic were encouraged to provide comments and item interpretation (i.e. cognitive debriefing). After a careful examination of responses from the pretest, researchers determined that no additional changes to the 37-item instrument were needed.
Main validation study
Members of a large web-based panel were recruited through Harris Interactive for the main validation study. Harris Interactive maintains a US database containing a self-elected population of members who routinely contribute to studies from this well-recognised research provider. Panel members and affiliated partner members were invited through a password protected email invitation to complete the instrument covering health-related topics. The panel consisted of several million people who have preagreed to participate in survey research. Panellists joined the online panel through 100 different sources that used diverse recruitment strategies (e.g. geographical placement, professional meetings and telephone recruitment) to reduce selection bias. Data integrity was maintained by password protection, reminder invitations and the availability of selected survey results after completion. Besides obtaining approval from an Institutional Review Board of the Olmsted Medical Center and the Mayo Clinic, the instrument was also reviewed by an ethics committee where the sample for the main study was obtained.
Respondents confirmed their desire to participate in the panel by clicking on a designated link and registering. Qualified respondents were US citizens, 18 years of age or older with a physician-confirmed diagnosis for chronic HCV, and were either receiving treatment for HCV or received treatment in the past. Through completing the questionnaire, participants accumulated points that could be used to purchase items of nominal value (<$20.00) at their discretion.
Data were analysed using spss 17.0 Windows (SPSS Inc., Chicago, IL, USA). Confirmatory factor analysis (CFA) and structural equation modelling (SEM) were performed using analysis of moment structures (amos), version 17.0, software and user's guide (James L. Arbuckle 1995–2006). First, descriptive statistics and t-tests were employed to assess demographic variables, symptom severity and any experience with treatment and treatment satisfaction. Second, a principal components exploratory factor analysis (EFA), using Varimax rotation to increase the interpretability of factors, was performed to identify items with the strongest relationship to respective factors. To be included for further analysis, items had to demonstrate acceptable loadings (≥0.3) on one factor and not have extensive cross-loadings on other factors. Item-to-total correlations were examined with items having Cronbach's α of 0.70 or higher retained for scale development. Third, after discriminant validity was substantiated with items loading on their appropriate constructs, reliability and validity were further assessed using CFA.
To assess model fit, modifications recommended by AMOS outputs were made to paths connecting items to constructs, the constructs themselves, and to paths existing among the measurement error terms to improve the fit between the CFA model and the data. Once modifications were made as provided, various fit measures were examined to assess the impact of these modifications on the CFA model. Fit measures included χ2, the Comparative Fit Index (CFI: >0.90 acceptable, >0.95 excellent), the Tucker-Lewis Index (TLI ≥0.90 acceptable), and Root Mean Square Error of Approximation (RMSEA), which should be ≤0.05 to indicate a good fit between the proposed CFA model and the data. Finally, after acceptable levels of fit and validity were demonstrated for the CFA model, SEM was used to assess the hypothesised relationship between the observed variables and unobserved (latent) constructs in the proposed structural model.
The average age for the fifteen community-based focus group participants was 45.7 years (range = 23–69) with males comprising 68% of sample. Eight patients received a single-episode of treatment using a combination of pegylated interferon and ribavirin, while two others received treatment twice. One patient had cirrhosis and 40% had elevated liver enzymes with one-half of those (20% overall) having elevated liver enzymes more than 1.5 times the upper limit of normal. With respect to disease and disease progression, several patients reported fatigue (43%), depression (14%), and most patients complained of anxiety regarding HCV. An initial viral response and decreased viral load at end of therapy were obtained for all individuals in their final round of therapy. Data at 6 months after therapy were available for all except one individual treated outside Minnesota who stated he was ‘cured.’ Counting the ‘cure’ as a sustained viral response, the documented sustained viral response was 70% (7 of 10) for the ten people treated one or more times.
Of major concern to these patients was the stigma surrounding the disease, particularly in reference to its perceived similarity to Human Immunodeficiency Virus and its association with drug abuse. Patients reported that this stigma prompted secrecy between those afflicted by the disease and their friends, family and co-workers. The most commonly elicited side effect of treatment was profound fatigue, followed by other side effects including depression, stomach pains, nausea, sexual dysfunction and immunosuppression. Despite approximately three-fourths of the patients having insurance coverage, there were several comments from focus-group participants relating to the burden of cost and insurance barriers. In addition, the hassle of frequent doctor visits, blood draws and medication injections were cited as ranging from mildly burdensome to overwhelming. Finally, patients provided extensive information relating to their treatment experience, satisfaction with treatment, self-reported liver function test results and the importance of family support.
Cognitive debriefing in 145 patients resulted in only minor modifications in the wording of items used in the final instrument, which was then available for the main validation study.
Main validation study
A total of 660 potential participants entered the password-protected site to initiate the survey process, 268 were not qualified and 38 entered the site, but did not complete the instrument. A total of 333 qualified participants who completed 85% or more of the instrument from 10 November 2010 to 17 November 2010 were included in the final analysis. Males comprised 55.0% of the sample. Participants were 82.3% Caucasian with an average age of 51 (s.d. = 12.1) years and had a diagnosis of chronic hepatitis C for approximately 12 (s.d. = 8.9) years (Table 1). A majority of the participants (55.3%) reported having depression, while others reported anxiety, history of drug use, alcohol use, allergic disease and diabetes. The reported source for hepatitis C virus was from IV drug use (26.1%), exposure to contaminated blood (36.9%) and tattoos (27.9%). Approximately three-fourths of the participants had insurance coverage for HCV. No differences were noted between symptom severity before and after treatment. However, results from linear regression analysis revealed a significant and negative relationship between length of time having a diagnosis of HCV and TS (β= −0.30; P <0.001). Patients (21%) currently undergoing treatment were diagnosed more recently compared with patients who received treatment in the past (mean = 5.9 years vs. mean = 13.6 years respectively; P <0.01).
Table 1. Sample characteristics (n = 333)
Gender (% male)
Age (mean years, s.d.)
Diagnosis for how long? (mean years, s.d.)
Comorbidities (% yes)
History of drug use
History of alcohol use
Allergic disease, asthma, breathing problems
Asian or Pacific Islander
Hepatitis C came from: (% yes)
IV drug use
Blood transfusion or contact contamination
Multiple sex partners
Receiving current treatment: (% yes)
Insurance coverage: (% yes)
Results from principal components EFA revealed a factor structure that was highly interrelated (KMO = 0.97), indicating that the domain of TS was well represented by the items. After removing items with low communalities (≤0.4), and any item that was not identifiable with any particular dimension the factor structure was reduced to 12 items (Cronbach‘s α = 0.95). The initial factor structure yielded two factors with eigenvalues either greater than 1 or very close to 1, accounting for 70.0% of the variance. However, the factor structure was not easily interpreted. After attempting a forced three-factor and four-factor solution, it was determined that the forced three-factor solution produced the best results with 75.0% of the variance explained. Despite the advantages of the three-factor solution, one factor alone contained 8 items and explained 38.4% of the variance relating to the dimension of treatment satisfaction.
Scale purification and responsiveness
Items from the EFA were further verified by examining the reliabilities for each dimension. Items were eliminated if the item-to-total correlation improved when the respective item was removed. Cronbach`s α for the three dimensions including Treatment Experience (TE), Side Effects (SE) and Social Aspects (SA) ranged from 0.70 to 0.90. Cronbach‘s α for the final 12 items was 0.95, indicating that the items were highly interrelated relative to variance resulting from measurement error (Table 2).
Table 2. Twelve item exploratory factor solution for patients with chronic HCVa
Cronbach α = 0.95; total explained variance = 75.0% using varimax rotation.
Scale: 1 = not important at all; 5 extremely important.
Side effects, α = 0.86
SE1 Dosing scheduled can be adjusted
SE2 Medication does not affect physical or sexual function
SE3 Side effects can be avoided
Treatment experience, α = 0.90
TE1 Medication use produces a complete cure
TE2 Currently used medications are effective
TE3 Medication safe for long-term use
TE4 Treatment works as expected
TE5 Medication use improves liver-function test
TE6 Treatment adds value to overall health
TE7 Relief from symptoms
Social, α = 0.70
S1 Support from family, friends, and others
S2 Feel better about myself after medication use
A one-way analysis of variance was performed to determine if the items comprising the composite measure of TE and the global measure of TS were able to detect differences in TS for patients who reported different levels (e.g. extremely satisfied compared to not satisfied at all) of TS from treatment for HCV. Results revealed that the items in the composite measure for TE were able to distinguish between patients with high/low levels of TS (P <0.05). Although explicit analysis of TS by SVR status was not possible due to data constraints, the dimension for TE contained items relating to patient perceptions of effectiveness and cure, thus providing evidence that patients associated higher levels of treatment satisfaction with the effectiveness of HCV therapy. Values representing changes in TS were in the predicted direction and were larger than the values obtained for the standard errors associated with the measurement of TS, suggesting that the resulting changes were true observed changes in TS.
Confirmatory factor analysis
Confirmatory factor analysis (CFA) was used to assess the fit between the hypothesised model and the data to further determine if the underlying constructs were unidimensional (the set of items was represented by one construct) and consistent with findings from EFA.[31, 32] The diagram in Figure 1 describes the relationship between the observed variables (represented by boxes) and the latent constructs (represented by circles). The curved lines connecting the latent constructs represent the correlation between these latent constructs in the measurement model, which should be allowed to correlate. Goodness of fit indexes for the final measurement model improved when the model was reduced from 12 items to 9 items (χ2 = 20.9, df = 23, P =0.59; CFI = 1.00, GFI = 0.99, TLI = 1.00, RMSEA = 0.001).All parameters were significant (P <0.05).
Structural equation modeling
Figure 2 presents a summarised structural equation model (S.E.M.) containing the standardised path coefficients between the dimensions, which were used to assess the hypothesised relationship among the latent constructs. Side Effects were positively correlated with Social Aspects (path coefficient = 0.85), while a strong positive relationship was observed between social aspects and treatment experience (path coefficient = 0.95). Treatment Experience was positively related to Treatment Satisfaction (path coefficient = 0.12). All standardised parameter estimates were significant (P <0.05), indicating that data from the sample supported an excellent fit between the data and the hypothesised model presented in Figure 2. The χ2 was 41.2, df = 31; P =0.104; CFI = 0.995; TLI = 0.992; RMSEA =0.032. Details of the SEM analysis can be found in Appendix A.
The purpose of the HCVTSat instrument was to better understand patients’ perceptions of treatment satisfaction with HCV therapy. The chronic aspects of the disease were considered during instrument development as many patients remain asymptomatic or mildly symptomatic and postpone therapy despite an understanding of the long-term risks associated with chronic HCV infection. The HCVTSat instrument is the first instrument developed and validated specifically to address the concerns of these patients. As more treatment options become available for HCV patients, implementation of the HCVTSat instrument may permit the comparative evaluation of the degree of treatment satisfaction and factors contributing to treatment satisfaction and patient experience with treatment regimens.
Results from this study also provided some insight into the relationship between social support from others, especially when social support was viewed from a more personal perspective of physical and sexual performance, and side effects within the context of the treatment experience. While others have observed the lack of a relationship between side effects and overall treatment experience with newly prescribed medications in the general population, the relationship between social aspects and side effects in this study was a very important predictor of the TE for patients with HCV. In one study, patients indicated that the loss of social support was related to concerns about possible transmission of HCV to family members and friends, ignorance leading to discrimination and feelings of isolation and to stress regarding the unpredictability of the disease. Given the strength of the relationship between SA and SE with respect to the TE and TS, and that SEs were perceived as significantly more important to those patients who were undergoing treatment currently compared with those patients who received treatment in the past (P =0.01), educational strategies would be imperative to help family members and friends understand HCV and to help improve their coping abilities and psychological well-being when undergoing treatment. Opportunities to integrate these findings with recently developed models to treat patients in underserved populations may provide additional impetus to help patients continue therapy and improve outcomes.
Treatment satisfaction continues to be an important outcome in the experience with therapy. In this study, the final SEM was evaluated to determine if a reciprocal relationship existed between TE and TS. From this assessment, only the path coefficient supporting the relationship going from TE to TS was significant. Thus, the four items; ‘medication use was effective,’ ‘medication worked as expected,’ ‘improvements in liver function test,’ and ‘added value to overall health’ assessed the TE, which was a predictor of overall TS with past therapy. As documented from the focus groups, patient perceptions of liver health that were reinforced through clinical evaluation and consultation appear to be an important driver of the TE for patients with chronic HCV.
Besides being the first instrument to assess TS in patients with chronic HCV, another contribution of this study was the use of SEM to assess the correlation between the TE and the global (exogenous) measure of TS. While global and general measures of TS may not always perform as desired,[22, 36] they are important from the perspective of clinical research for use as a validation measure in comparison with the data obtained from patient history, other instruments and clinical evaluation. Furthermore, instructing patients to consider multiple aspects of their treatment experience when making global ratings might increase the validity of their perceptions if such ratings more adequately characterise patient experiences with their treatment compared with global ratings without such instructions.
With the HCVTSat instrument, both TE and TS appear to capture subtle nuances that are characteristic to these patients. Although clinical data from medical records were not available, this relationship may be attributed to the asymptomatic nature of the infection for many patients. Thus, undergoing treatment without having overt symptoms of HCV may leave some patients feeling worse with subsequent adverse consequences on their perceptions of treatment satisfaction. Alternatively, in another study of patients with type 2 diabetes, it was noted that TS was inversely related to insulin treatment and the presence of kidney disease. Although co-morbidities in this study were not significant predictors of TE or TS, chronic kidney disease and diabetes have been associated with an increased risk of mortality for patients with chronic HCV. While the negative effects of therapy on TS may be compounded by the presence of co-morbid conditions and by decisions to postpone treatment until clinical evidence of chronic liver disease emerges, treatment deferral is not without cost and may lead to worse outcomes. For example, patients who remain asymptomatic for years usually do not perceive the full effects of chronic HCV until they experience liver cirrhosis, which affects about 20% of patients. Therefore, early adoption of treatment offers multiple benefits and satisfaction with treatment may enable salutary outcomes.
Participants for this study were obtained from a large medical centre in Rochester, MN and through Harris Interactive. To be included in the study, patients were physician-diagnosed as having chronic HCV, and were either currently undergoing treatment or were treated in the past. However, without access to medical records, any information provided could not be confirmed. Despite a rigorous development process for the instrument, EFA was unable to provide a clear cut factor solution, thus necessitating the use of a forced factor solution. While this approach is not uncommon, the final items used from the EFA to develop the SEM model may not represent all perceptions of TS. Despite the significant relationship between TE and TS, the relationship was somewhat attenuated as the multiple items comprising SA, SE, and TE were highly inter-correlated and thus related to the single-item global measure of TS only through TE. With only 145 patients included from the medical centre, it was not possible to perform a cross-validation study with the entire SEM model. However, the construct representing the TE was cross-validated and supported in both groups. In addition, no significant differences were noted between patients who were undergoing treatment currently or who were treated in the past with respect to treatment satisfaction. Furthermore, perceptions of TS elicited from patients and participants using a subjective rating scale may relate to measures of effectiveness other than SVR. Nonetheless, future studies are needed to determine the responsiveness of this instrument in patients receiving DAA agents and in conjunction with sustained virological response data for patients from multiple practice settings. Considering that patients included in this study came from a tertiary practice setting and large panel of participants in the US, the characteristics of these patients would suggest an older population that acquired HCV through blood transfusions (e.g. haemophiliacs, injuries, etc.). Thus, further validation of the HCVTSat should include populations that were underrepresented in the present study (e.g. younger patients with HCV, drug users and patients in methadone maintenance programs).
In both psychology and marketing research, treatment satisfaction is defined as an attitudinal response arising from value judgments that patients make concerning treatment experiences and clinical encounters. Consequently, the assessment of treatment satisfaction is recommended temporally at the end of therapy while impressions remain strong. The evolution of DAA regimens may offer therapies characterised by reduced duration and limited symptomatic impairment (compared with current interferon-based standard of care) with potential positive impact on treatment satisfaction. The HCVTSat instrument may be effectively implemented at the conclusion of therapy in longitudinal studies of these new DAAs so as to document overall comparative treatment satisfaction with oral versus interferon-based regimens and other factors contributing to treatment satisfaction.
The HCVTSat instrument was developed to evaluate treatment satisfaction as part of the total experience with therapy for patients with chronic HCV. As treatment options and patterns for HCV patients evolve, a comparative evaluation of satisfaction with treatment will be an important factor influencing selection of therapy and the motivation to initiate and continue therapy. Findings from this study support the use of the HCVTSat to evaluate patient experiences that may lead to improvements in treatment satisfaction. However, additional studies are needed to validate the HCVTSat in conjunction with SVR and in patients in underrepresented populations.
Guarantor of the article: S. L. Szeinbach.
Author contributions: SLS, RWB, BD and BPY designed the study. LGR and DL were responsible for data collection in Rochester, MN. Data for the main study were provided to SLS by Harris Interactive. Data analyses were performed by SLS, LGR, DL and BPY. Data interpretation was performed by SLS, RWB and BPY. The manuscript was drafted by SLS, LGR, DL and BPY. A critical review of the manuscript was provided by RWB and BD. All authors reviewed and contributed to the final version of the manuscript. All authors approved the final version of this manuscript.
We acknowledge the insightful review and contribution provided by Dr Mudra Kapoor.
Declaration of personal interests: Drs Robert W. Baran and Birgitta Dietz are employed by Abbott Laboratories.
Declaration of funding interests: Sheryl L. Szeinbach and Barbara Yawn received research support from Abbott Laboratories, Abbott Park, IL to complete this study.
Structural equation model of dimensions relating to treatment satisfaction for patients with chronic HCV