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Letters

Canadian hepatitis C virus screening guideline: a disconnect between evidence and recommendations

Alex Haines, William W.L. Wong and Murray Krahn
CMAJ September 11, 2017 189 (36) E1150; DOI: https://doi.org/10.1503/cmaj.733330
Alex Haines
Health Economist, Toronto Health Economics and Technology Assessment Collaborative, Toronto General Hospital Research Institute, Toronto, Ont.
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William W.L. Wong
Assistant Professor, School of Pharmacy, University of Waterloo, Kitchener, Ont.
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Murray Krahn
Director, Toronto Health Economics and Technology Assessment Collaborative, Toronto General Hospital Research Institute, Toronto, Ont.
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We believe that the evidence supporting the recommendations by the Canadian Task Force on Preventive Health Care1 has been misinterpreted in several key ways.

First, we disagree that our decision model (commissioned by the Public Health Agency of Canada) was “very low quality evidence.”1 We believe that the model, when judged by the correct standards, is of good quality. For example, in a systematic review by Coward and colleagues, the model received a perfect score using the Consolidated Health Economic Evaluation Reporting Standards checklist.2 The fact that the Grading of Recommendations Assessment, Development and Evaluation (GRADE) system was used to evaluate the model for the guideline represents a misunderstanding of both modelling and GRADE. The GRADE checklist is specifically designed for assessing primary clinical evidence, not secondary synthetic methods such as decision or economic models, which integrate a wide heterogeneous set of epidemiologic, economic and patient preference evidence. The GRADE handbook specifically states that models should not be included in evidence profiles.3 Our model was not only included but considered to be observational evidence, which it is not.

Other limitations for applying GRADE criteria to models are discussed in the review by Rehfuess and colleagues.4 Models have been and are routinely used around the world to inform public health and reimbursement decisions, clinical guidelines and screening policy. In the area of hepatitis C virus screening, where benefits occur decades into the future, modelling is the only practical option we have for fully incorporating all health and cost outcomes.

Second, the evidence cited to highlight the harms of screening seems, on direct inspection, to suggest the opposite. In three of the studies cited, where patients are directly asked their willingness to be screened, the proportion that approve exceeds 90%.5–7 Each paper cited by the task force either concludes with a strong preference toward screening or is designed to highlight implementation issues that need to be overcome to improve screening efficacy. It is never suggested that screening itself is harmful to patients and should not take place. The survey commissioned by the task force concludes: “In considering the benefits of screening and harms of treatment, participants reported a strong preference to [be] screened for hepatitis C (median rating of 8 [interquartile range 6–9] on a 9-point scale).”8 This is a very strong consensus in favour of screening. It is perplexing to us that such a negative conclusion was reached on the basis of this evidence.

We are not screening evangelists, and our concerns involve the interpretation of the evidence presented to the task force. We feel that rational public policy requires a fair and considered evaluation of all available evidence, including evidence from models and from patients.

Footnotes

  • Competing interests: William Wong and Murray Krahn have received research support from the Canadian Liver Foundation.

References

  1. Canadian Task Force on Preventive Health Care. Recommendations on hepatitis C screening for adults. CMAJ 2017;189:594–604.
    1. Coward S,
    2. Leggett L,
    3. Kaplan GG,
    4. et al
    . Cost effectiveness of screening for hepatitis C virus: a systematic review of economic evaluations. BMJ Open 2016;6:e011821.
    1. Schünemann H,
    2. Brożek J,
    3. Guyatt G,
    4. et al
    ., editors. GRADE handbook. GRADE Working Group; 2013. Available: http://gdt.guidelinedevelopment.org/app/handbook/handbook.html#h.f06pwvbsyasx (accessed 2017 July 6).
    1. Rehfuess EA,
    2. Akl EA
    . Current experience with applying the GRADE approach to public health interventions: an empirical study. BMC Public Health 2013;13:9.
    1. Myers RP,
    2. Crotty P,
    3. Town S,
    4. et al
    . Acceptability and yield of birth-cohort screening for hepatitis C virus in a Canadian population being screened for colorectal cancer: a cross-sectional study. CMAJ Open 2015;3:E62–7.
    1. Norton BL,
    2. Voils CI,
    3. Timberlake SH,
    4. et al
    . Community-based HCV screening: knowledge and attitudes in a high risk urban population. BMC Infect Dis 2014;14:74.
    1. Vallabhaneni S,
    2. Macalino GE,
    3. Reinert SE,
    4. et al
    . Prisoners favour hepatitis C testing and treatment. Epidemiol Infect 2006;134:243–8.
    1. Buckland D,
    2. Sayal R,
    3. Bashir N,
    4. et al
    . Canadian Task Force on Preventive Health Care: patient preferences in considering hepatitis C screening and treatment outcomes: phase two. Toronto: Li Ka Shing Knowledge Institute, St. Michael’s Hospital; 2016. Available: http://canadiantaskforce.ca/guidelines/published-guidelines/hepatitis-c/ (accessed 2017 July 27).

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Copyright 2019, Joule Inc. or its licensors. All rights reserved. ISSN 1488-2329 (e) 0820-3946 (p)

All editorial matter in CMAJ represents the opinions of the authors and not necessarily those of the Canadian Medical Association or its subsidiaries.

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