ABSTRACT
Background: Chronic hepatitis C virus (HCV) infection is common among people who inject drugs (PWID) and is associated with morbidity and premature death. Although HCV can be cured, treatment may be inaccessible. We studied HCV testing, status and treatment among marginalized people who use drugs in Ottawa, Canada, a setting with universal insurance coverage for physician services.
Methods: We analyzed data from the Participatory Research in Ottawa: Understanding Drugs study, a cross-sectional, peer-administered survey of people who use drugs from 2012 to 2013. We linked responses to population-based health administrative databases and used multivariable Poisson regression to identify factors independently associated with self-reported HCV testing, self-reported positive HCV status, and database-determined engagement in HCV treatment. Results: Among 663 participants, 562 (84.8%) reported testing for HCV and 258 (45.9%) reported HCV-positive status. In multivariable analysis, HCV-positive status was associated with female gender (RR 1.27; 95%CI 1.04 to 1.55), advancing age (RR 1.03/year; 95%CI 1.02 to 1.04), receiving disability payments (RR 1.42; 95%CI 1.06 to 1.91), injecting drugs (RR 5.11; 95%CI 2.64 to 9.91), ever injecting with a used needle (RR 1.30; 95%CI 1.12 to 1.52), and ever having taken methadone (RR 1.26; 95%CI 1.05 to 1.52). Of HCV positive participants, 196 (76%) were engaged in primary care but only 23 (8.9%) had received HCV therapy. Conclusions/Importance: Although HCV testing and positive status rates are high among PWID in our study, few have received HCV treatment. Innovative initiatives to increase access to HCV treatment for PWID are urgently needed.
Introduction
People who inject drugs (PWID) have high rates of hepatitis C virus (HCV) infection. More than 60% of PWID in Canada have chronic HCV infection and 83% of incident HCV infections occur among PWID (Remis, Citation2007). Chronic HCV is associated with liver fibrosis and failure, cancer, and premature death (Grebely et al., Citation2015a). Timely HCV testing is essential for preventing disease progression and for targeting public health strategies to prevent forward transmission (Grebely et al., Citation2015b). However, health care systems, care and social service settings, providers, and systematic discrimination present potential barriers to HCV testing and treatment (Paterson, Hirsch, & Andres, Citation2013; Pauly, McCall, Browne, Parker, & Mollison, Citation2015; Van Boekel, Brouwers, Van Weeghel, & Garretsen, Citation2013). Moreover, PWID who have chronic HCV also have high rates of concurrent mental health diagnoses and incarceration, factors which further necessitate enhancing engagement and retention in care for this population (Canadian Public Health Association, Citation2004; Millson, Leonard, Remis, Strike, & Challacombe, Citation2004).
While highly effective Direct Acting Antiviral (DAA) treatments can cure HCV for most people living with chronic infection, PWID may not receive treatment for several reasons (Hellard, Doyle, Sacks-Davis, Thompson, & McBryde, Citation2014). First, the toxicity, arduous treatment regimens, and limited effectiveness associated with interferon-based therapies have presented substantial barriers to treatment adherence and contributed to a lack of demand for treatment in this population (Grebely et al., Citation2008; Myers et al., Citation2015). Second, the high cost of DAA therapies have restricted access for marginalized PWID who often rely on public drug insurance, which has prioritized coverage based on fibrosis level and left decisions to treat active PWID up to physician discretion (Marshall et al., Citation2016). Third, despite clinical guidelines endorsing treatment for all patients with chronic HCV (Chung et al., Citation2015; European Association for the Study of the Liver, Citation2015; Myers et al., Citation2015), some clinicians are likely unaware of newer findings of the effectiveness of treating active PWID, and thus may continue to base treatment decisions on previous concerns, such as the risk of reinfection, low treatment adherence, or worse side effects due to comorbid conditions (Aspinall et al., Citation2013; Edlin et al., Citation2005; Grebely, Oser, Taylor, & Dore, Citation2013b; Myers et al., Citation2015).
In response to such barriers, some have argued that denying HCV care to PWID is discriminatory and further contributes to stigmatization of a population with high health care needs (Grebely et al., Citation2015a, Citation2016a; Wolfe et al., Citation2015). Furthermore, recent data demonstrates that adherence rates can be high among people with concurrent substance use and that treatment of HCV-infected PWID is cost-effective even considering potential reinfection rates (Aspinall et al., Citation2013; Grebely et al., Citation2015b, Citation2016b; Martin et al., Citation2012, Citation2013; Scott, Iser, Thompson, Doyle, & Hellard, Citation2016). Some even support prioritizing PWID in HCV treatment approaches as a way to prevent further transmission of the virus, and propose that the scale up of HCV treatment among PWID should be combined with increased support of harm reduction interventions, such as needle and syringe programs and opioid agonist therapy (European Association for the Study of the Liver, Citation2015; Hellard et al., Citation2014; Martin et al., Citation2013, Citation2015). Still, unaddressed social, substance use, and mental health issues among PWID may be more pressing than treating HCV, and as these are underlying factors behind the HCV epidemic, any HCV treatment approach should also address these issues in order to optimize health outcomes among this population (Tyndall, Citation2015).
To better understand these issues, we studied the uptake of HCV testing and treatment among marginalized people who use drugs in Ottawa, Ontario, Canada. Ontario has a single payer publicly funded health system with universal access for necessary physician services. We described HCV testing and status rates, identified predictors of HCV testing and HCV-positive status, and assessed use of HCV-specific treatment. We used data from the Participatory Research in Ottawa: Understanding Drugs (PROUD) study (Lazarus et al., Citation2014), a community-based cohort of people who use drugs in Ottawa, where rates of HCV and HIV are among the highest of any major Canadian city (Millson et al., Citation2004).
Methods
Data sources
Data for our study were obtained in two ways. First, as described previously (Lazarus et al., Citation2014), the PROUD study used a street-based peer recruitment approach to enrol participants 16 years of age or older who had injected or smoked drugs other than marijuana in the 12 months prior to recruitment. Participants completed a peer or medical student-administered survey that included questions about socio-demographic information and substance use, environmental-structural factors (e.g., legal issues, housing), interpersonal relationships (e.g., connection to community, sexual history), harm reduction practices, health status, and health and social services use.
Second, additional data were obtained by linking the survey responses for consenting participants with health administrative databases held at the Institute for Clinical Evaluative Sciences (ICES). Accredited researchers have access to ICES databases through a data sharing agreement with the Ontario Ministry of Health and Long-Term Care. We performed linkage deterministically using unique encoded identifiers based on participants’ reported Ontario Health Insurance Plan (OHIP) numbers if available, or probabilistically based on their names, dates of birth, and postal codes. After linkage, we excluded duplicates while retaining responses with the most complete data.
We used the following ICES databases for our study: the Registered Persons database, which holds mortality and demographic data for all provincial health care eligible residents; the 2006 Statistics Canada Census data to attribute the household income quintile to linked residential postal code as a proxy for socioeconomic status; the OHIP billing claims system, which contains 95% of physician services provided in the province; the Community Health Centre database, which contains encounter information for patients seen in Ontario's Community Health Centres; the Discharge Abstract Database, which captures all provincial hospital admission and discharge data, including information relevant to HIV and mental health diagnoses; the National Ambulatory Care Reporting System, which contains encounter-level information on visits to emergency departments, including physician services and diagnoses; the Client Agency Program Enrolment Registry, which compiles patient rosters for individual family physicians; the ICES Physician database, which contains physician demographic, training and practice setting information; and the Ontario Drug Benefits (ODB) to identify prescription claims by individuals aged 65 or older or who received income assistance, disability payments, or publicly subsidized catastrophic drug coverage.
Variables
We categorized sex using self-reported male or female gender from the PROUD survey or ICES-defined sex at birth for participants who reported other gender classifications (two-spirited or other) or who did not respond. Two-spirited is a common term within some Indigenous cultures, typically referring to a “third gender” that can include any combination of gender, sex or sexual orientation characteristics. We excluded self-reported transgender individuals who would be at risk of re-identification if analysed as a distinct gender category and for whom numbers were too small (n ≤ 6) to make valid inferences.
We used the Johns Hopkins Adjusted Clinical Groups Case-Mix Assignment software (Sun Microsystems Inc., Santa Clara, CA)(Johns Hopkins University Press, Citation1997) to categorize medical comorbidity by assigning individuals to one of 32 distinct Aggregated Diagnosis Groups (ADGs) based on condition duration, severity, diagnostic certainty, etiology, and specialty care involvement. Comorbidity burden was classified as low (≤5 ADGs), medium (6–9 ADGs) and high (≥10 ADGs). People with mental health conditions were ascertained using previously validated algorithms (Antoniou, Zagorski, Loutfy, Strike, & Glazier, Citation2011; Steele, Glazier, Lin, & Evans, Citation2004). We calculated the total number of primary care visits for each patient, excluding visits that were exclusively for purposes of opioid agonist therapy or monitoring.
Outcomes
We examined several HCV-related outcomes. First, we considered the rate of self-reported HCV testing among PROUD participants, determined by responses to the question “Have you ever been tested for hepatitis C?.” Second, among participants who answered yes to this question, we determined the prevalence of self-reported HCV infection using the question “What was the result of your last hepatitis C test?.” This question did not differentiate between testing for antibodies (serostatus) or testing for RNA or core antigen. Third, we examined patterns of engagement in outpatient medical care. We defined patients as engaged in primary care if they had three or more outpatient visits to the same family physician in any two year period starting two years before survey completion (with surveys completed between March and December 2013) and continuing for two years after survey completion (or until death). We categorized participants as having received treatment for HCV if they obtained at least one prescription for an HCV medication (see the Appendix) in the period starting two years prior to survey completion and February 2017; this span includes the time during which direct-acting HCV antivirals became available in Canada. We selected a long time horizon for this analysis, recognizing that some participants and prescribers may have delayed initiation of HCV therapy while waiting for new medications to be approved or reimbursed.
Analyses
All analyses were conducted at ICES. For the majority of PROUD survey questions, we dichotomized responses as “yes” vs. “other” (the latter including “no,” “no answer,” “don't know” and missing responses, depending on which options were available for each question). Across the survey questions, up to 25 participants provided “don't know” responses, up to 30 participants provided “no answer” responses, and up to 20 participants had missing responses. We also performed a complete case analysis for each multivariable model and the results were unchanged.
We used descriptive statistics to summarize the study populations with measures of central tendencies and dispersion. We compared groups by testing status and test result status using Wilcoxon rank sum tests for continuous variables and chi squared tests or Fisher's exact test as appropriate for categorical variables. As both self-reported testing participation and self-reported positive status were common events, we conducted nonparsimonious multivariable Poisson regression with robust error estimation to examine associated variables. We adjusted for selected covariates that the research team felt to be potential independent predictors or confounders of HCV testing and HCV-positive status, respectively, excluding some factors due to expected collinearity. We reported associations as rate ratios with 95% confidence intervals. To preserve confidentiality, cell sizes of 6 or less were reported in aggregate. SAS statistical software, version 9.3 (SAS Institute Inc., Cary, NC), was used to conduct all statistical analyses. This study received approval from the Ottawa Health Sciences Network Research Ethics Board (OHSN-REB #20120566-01H) and the institutional review board at Sunnybrook Health Sciences Centre in Toronto, Canada. We used a p-value threshold of 0.05 to determine statistical significance.
Results
A total of 858 PROUD participants completed the survey from March to December 2013, with 798 agreeing to linkage to ICES. After we excluded participants who did not have Ontario health insurance and those with duplicate enrolment, 663 of 782 participants (85%) were successfully linked. Among linked participants, 76% were men, the mean age was 41 years, and 69% lived in a neighbourhood in one of the lowest two income quintiles. Receiving disability or income assistance was common (76%). displays characteristics across all participants, only participants who reported testing, and only those who reported HCV positive status.
Table 1. Characteristics of the total participant cohort, participants by reported hepatitis C (HCV) testing participation, and participants by reported HCV status (limited to those who reported being tested for HCV (n = 562)).
Self-reported HCV testing participation
Among the PROUD participants linked to ICES, 562 (84.8%) reported previous testing for HCV. Rates were high among both participants who had ever injected (91.6%) and those who had never injected (69.2%). The majority of participants indicated that their most recent HCV test occurred in 2012 or 2013 (the year of the survey and one year prior). Self-reported HCV testing rates were lower among people who did not report English or French as their first language (71.4%). HCV testing rates were higher for those who reported that they had ever injected with a used needle (95.7%) or a needle whose previous use was unknown (95.2%), or had ever taken methadone (96.0%). Note that participants self-reported whether they had “ever been on methadone,” thus we cannot distinguish between those who obtained it via prescription or illicitly. In multivariable analysis (), no variables were significantly associated with self-reported HCV testing participation.
Table 2. Multivariable Poisson regression analysis of reported hepatitis C (HCV) testing (n = 663), adjusted for listed covariates.
Self-reported HCV status
Among the 562 participants who reported HCV testing, 258 (45.9%) reported testing HCV-positive and this was associated with older age. Reported HCV-positive status prevalence was higher among women (55.2%), those with the highest number of comorbidities (55.3%) and who reported being HIV-positive (80.4%). From a drug use perspective, the proportion reporting positive HCV results was higher among those who had ever injected drugs (58.9%), used drugs via both injection and noninjection (62.3%), injected with a used (71.8%) or unknown needle (61.5%), inject with other people usually, sometimes, or occasionally (64.6%) or never or other (62.1%), most frequently inject in a house or apartment rather than a public place (64.8%), had a history of overdose (58.5%) and had been taken to the emergency department or hospital at last overdose (55.7%). Among people who did not report injecting any drugs, 9 (6.5%) reported testing positive for HCV.
After adjustment (), among participants who reported having been tested, variables significantly associated with reported HCV-positive status included being female (RR 1.27; 95%CI 1.04 to 1.55), advancing age (RR 1.03; 95%CI 1.02 to 1.04), receiving prescription drug benefits through the Ontario Disability Support Program (RR 1.42; 95%CI 1.06 to 1.91), having previously injected drugs (RR 5.11; 95%CI 2.64 to 9.91), having ever injected with a used needle (RR 1.30; 95%CI 1.12 to 1.52), and having ever taken methadone therapy (RR 1.26; 95%CI 1.05 to 1.52). Only education, specifically having attended at least some college or university (RR 0.73; 95%CI 0.55 to 0.96) or having completed some college or university (RR 0.65; 95%CI 0.45 to 0.92), compared to having high school education or less, was associated with lower odds of positive HCV status.
Table 3. Multivariable Poisson regression analysis of reported hepatitis C (HCV) status (limited to those who reported being tested for HCV (n = 562)), adjusted for listed covariates.
Care engagement
Of 258 PROUD participants who reported being HCV-positive, 196 (76%; 95%CI 56.97 to 69.08) were engaged in primary care, whereas only 23 (8.9%; 95%CI 5.74 to 13.08) had received HCV therapy. As the numbers are small, we are unable to report most information about characteristics related to engagement in HCV treatment. Trends in the data indicate that of the 258 participants reporting HCV positive status, those who received HCV therapy may be older, include more women (12.5%) than men (7.3%), and have fewer comorbidities.
Discussion
We studied HCV testing participation, HCV status, and engagement in HCV therapy among a marginalized population of people who use drugs with a high prevalence of HCV infection among the subgroup of PWID. Although a large majority of participants had received HCV testing, only 9% of people who reported having chronic HCV infection had received HCV treatment. Our results underscore the importance of moving beyond identifying people with chronic HCV infection and towards comprehensively studying interventions that address the patient, provider, system, and structural barriers to effectively delivering HCV treatment.
Self-reported HCV testing was greater than 85% in our cohort and was over 95% among people at high risk for HCV, such as those who share needles. The PROUD survey asked only about lifetime testing, so we are unable to determine the frequency of testing. Overall, our results indicate that HCV testing among marginalized people who use drugs has been a public health success in Ottawa. Further success is evident by the recency testing, with over half of participants tested within 2 years prior to the survey. Importantly, such testing is available without charge at harm reduction sites, including needle and syringe distribution programs, as well as in clinic settings. Nevertheless, research has indicated that HCV testing programs are necessary to limit HCV transmission but are not sufficient, as awareness of HCV results may only have a small effect on risky injections (Aspinall et al., Citation2014; Bruneau et al., Citation2014).
Our finding that about 60% of PWID reported a positive HCV result is consistent with estimates from other studies in Ottawa using laboratory-based data (Bayoumi et al., Citation2012; Public Health Agency of Canada, Citation2013). 462 (69.7%) of total participants reported ever injecting drugs, 58.9% of whom reported HCV positive status. In comparison, 326 (49.2%) participants had injected within the past year, 62.3% of whom were HCV positive. Similar results have been reported from cohorts of PWID internationally, particularly those in high-income countries (Grebely et al., Citation2013a). However, the PROUD survey asked only about positive tests but did not distinguish between a positive antibody test, a positive HCV DNA test, or other HCV-related tests and we could not confirm self-reported test results with laboratory data; thus our findings of differences between groups may be confounded by self-report. Nevertheless, higher self-reported HCV-positive results with increasing age and among women may be of particular concern, as fibrosis in women with chronic HCV infection may progress more rapidly after menopause (Corsi, Karges, Thavorn, Crawley, & Cooper, Citation2015). The higher rates may also reflect greater engagement in care among these groups.
Among people who did not report a history of ever injecting, 6.5% reported a positive HCV test, which could indicate misclassification due to self-report regarding injection or HCV status. Alternatively, this finding may reflect an increased risk of HCV infection associated with cocaine or crack use, and underscores that all people who use drugs, including people who do not inject, may be at higher risk of HCV infection (Aaron et al., Citation2008; Fischer, Powis, Cruz, Rudzinski, & Rehm, Citation2008). The 6.5% prevalence rate is certainly higher than general population rates for HCV, even among birth cohorts with the highest prevalence (Bolotin et al., Citation2018; Remis, Citation2007). Moreover, 30.9% of our participants who had never injected reported no testing for HCV (vs. 8.4% of those who had ever injected), thus it is possible that some were unaware of their positive status. More research is needed to understand true rates and reasons for transmission among people who use drugs but do not inject.
Having ever injected drugs, ever injected with a used needle, receiving disability benefits or ever taking methadone were all associated with reporting as HCV positive. There was also a clear education gradient, with the highest education level associated with the lowest risk of reporting HCV positive. These findings highlight that suboptimal HCV care is likely concentrated within the most disadvantaged PWID, and that HCV prevention and treatment services should focus on integration of addiction and social services within targeted primary care services for PWID.
Our most striking finding was that only 9% of participants who self-reported as testing positive for HCV had been prescribed HCV antiviral drugs between 2011 and 2017 through public drug insurance plans. While we may have underestimated prescriptions due to misclassification of people with private insurance or those obtained through exceptional access programs (although participant numbers in these categories are expected to be small), 76% of our cohort used the public drug insurance plan, indicating potential eligibility. However, interferon-based treatment could have been contraindicated among many participants due to mental health issues, housing instability, or patient refusal due to the need for needles (Marshall et al., Citation2016; Myers et al., Citation2015). Our results are also consistent with other studies that have found low rates of treatment (Public Health Agency of Canada, Citation2013). People who use drugs face multiple barriers to care, including at the provider level (e.g., discrimination), system level (e.g., lack of drug insurance, lack of flexible clinic hours), and structural level (e.g., laws related to drug use); these barriers also interact in dynamic ways within specific contexts (Grebely et al., Citation2013b; Johnson, Toliver, Mao, & Oramasionwu, Citation2014; Wagner et al., Citation2009; Wolfe et al., Citation2015). Patient-related barriers, such as frequent injecting of drugs, may also be important, although evidence indicates that people who are actively using drugs can also be highly treatment adherent (Gonzalez, Fierer, & Talal, Citation2017; Grebely et al., Citation2013a). Obtaining HCV treatment may also serve as a catalyst for some PWID to reduce their drug use or increase other self-care behaviors (Batchelder, Peyser, Nahvi, Arnsten, & Litwin, Citation2015).
Within our study time period, potential access to HCV drugs changed over time as new drugs were introduced and reimbursement criteria changed. For people with public drug insurance, direct-acting HCV antivirals were restricted throughout the study period to people with moderate or advanced liver disease (at least stage 2)(Marshall et al., Citation2016), which we were unable to assess but it was unlikely to affect many in our relatively young cohort. On February 28, 2017, coinciding with the last update of our data source, coverage of DAA agents through ODB was expanded with a plan to provide access for people with all fibrosis scores within 12 months (Ministry of Health and Long-Term Care, Citation2017); hence our data may serve as a baseline for future work to understand the impact of this change. Furthermore, the PROUD survey did not assess willingness to use HCV therapies, which may also have changed over time.
To expand HCV treatment among PWID, efforts should capitalize on the current infrastructure that has facilitated HCV testing in our Ottawa population. Lessons learned regarding care engagement in the HIV community, such as the benefits of multidisciplinary teams and intensive case management, may also be applicable to increase linkage and retention in HCV therapy (Meyer et al., Citation2015). For example, integrated care models should be established between primary care providers and infectious diseases or addiction specialists to ensure continuity in managing HCV treatment, while concurrently providing comprehensive chronic illness care to address the many comorbid health and social issues faced by PWID (Artenie et al., Citation2015; Artenie, Bruneau, Lévesque, & Wansuanganyi, Citation2014; Gonzalez et al., Citation2017). Multidisciplinary and tailored approaches are needed as it is clear that “one size does not fit all”(Bruggmann & Litwin, Citation2013). In Toronto and Victoria, community health centers with existing services targeted to PWID have capitalized on their infrastructure to develop successful HCV care models (Grebely et al., Citation2015a; Mason et al., Citation2015; Milne et al., Citation2015), including low-threshold HCV treatment integrated in a primary care setting, with access to a variety of social supports such as case management, counseling, outreach and peer support. These models employ a harm reduction approach and serve as examples for other health care settings to deliver more accessible and equitable HCV treatment for PWID. One of the care models provided weekly support groups for HCV program participants at three different sites, while the other included on-site opioid substitution and HIV treatments. Coordinating HCV care directly through opioid substitution therapy clinics also shows promise (Grebely et al., Citation2016a; Litwin et al., Citation2009). Notably, the successful care models tend to do far more than offer HCV treatment: they target the underlying social determinants that are key causes of the HCV epidemic, which facilitates not only prevention of HCV reinfection or new infections but also improvement of other pertinent health outcomes among marginalized communities of PWID (Mason et al., Citation2015; Milne et al., Citation2015; Tyndall, Citation2015). Our study adds to the evidence for these emerging approaches, in particular integrating HCV treatment with primary care services. Expanding these efforts to other settings may also require implementing strategies to reduce health professionals’ negative attitudes toward people who use drugs, such as targeted training or enhancing connections with community-based support services, especially among generalist physicians who may lack adequate training on addiction-related issues (Artenie et al., Citation2015; Van Boekel et al., Citation2013).
Our study's strengths include use of a community-based participatory approach and integration with detailed measures of health and health care based on administrative health records within a publicly funded, single payer system. However, our cohort includes a marginalized population of people who use drugs and our results may therefore not be generalizable to other people who use drugs. Furthermore, participants’ self-reported responses may have been biased due to limited recall, miscomprehension, or social desirability.
Conclusions
We found high HCV testing rates among marginalized people who use drugs in our study, particularly among people with injection practices that put them at high risk for HCV infection. We also found high rates of HCV among PWID, yet very few participants received HCV treatment. Over 75% of HCV-positive people who use drugs were engaged in primary care, suggesting that there are many missed opportunities to engage patients in HCV care and treatment. Current HCV DAA regimens remove previous key barriers to HCV treatment, including the harsh side effects, burdensome administration, and lack of effectiveness for certain genotypes. Used in combination with enhanced efforts to engage patients in care and shared health care models between regional specialized HCV clinics and primary care providers, there is great opportunity to increase treatment initiation and completion in this population. Overall, our results suggest that innovative approaches to HCV care for PWID should be considered, including involving peers in care, locating care in harm reduction environments, integration of HCV care with substance use and social service delivery, and use of telehealth services (Gonzalez et al., Citation2017; Johnson et al., Citation2014; Meyer et al., Citation2015; Talal, Thomas, Reynolds, & Khalsa, Citation2017; Tyndall, Citation2015).
Declaration of interest
The authors have no conflicts of interest to declare.
This study was supported by the Institute for Clinical Evaluative Sciences (ICES), which is funded by an annual grant from the Ontario Ministry of Health and Long-Term Care (MOHLTC). The opinions, results and conclusions reported in this article are those of the authors and are independent from the funding sources. No endorsement by ICES or the Ontario MOHLTC is intended or should be inferred.
This project was also supported by grants from the Canadian Institutes of Health Research (CIHR) and the Ontario HIV Treatment Network (OHTN).
Acknowledgments
We are grateful for the contributions of all participants in the cohort study and the PROUD Community Advisory Committee. We thank IMS Brogan Inc., Ottawa, for use of their Drug Information Number Database.
Parts of this material are based on data and/or information compiled and provided by CIHI. However, the analyses, conclusions, opinions and statements expressed in the material are those of the authors, and not necessarily those of CIHI.
We acknowledge the Ontario HIV Treatment Network Cohort Study (OCS) for use of the HIVOHTN database.
Funding
Canadian HIV Trials Network, Canadian Institutes of Health Research.
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Appendix:
List of HCV drug codes (prescriptions used to identify participants who had received HCV therapy)