Digestive Diseases and Sciences

, Volume 64, Issue 10, pp 2784–2797 | Cite as

Content Validity and Reliability of a Self-Report Measure of Medication Nonadherence in Hepatitis C Treatment

  • Corrine I. VoilsEmail author
  • Heather A. King
  • Carolyn T. Thorpe
  • Dan V. Blalock
  • Ian M. Kronish
  • Bryce B. Reeve
  • Colleen Boatright
  • Ziad F. Gellad
Original Article



Nonadherence to direct-acting agents (DAAs) for hepatitis C (HCV) decreases viral response. To measure nonadherence to DAAs, a reliable, valid, and easily implemented method is needed.


The goals of this study were to refine a previously validated (in patients with hypertension) self-report measure of extent of nonadherence and reasons for nonadherence in the context of DAAs and to obtain initial evidence of content validity and reliability.


Phase I involved two focus groups with patients with HCV (n = 12) and one focus group with prescribers of HCV medications (n = 6) to establish content validity of reasons for nonadherence. Subsequent cognitive interviews with patients (n = 11) were conducted to refine items. Phase II was a prospective cohort study involving weekly administration of the refined measure by telephone to patients (n = 75) who are prescribed DAAs to evaluate reliability and consistency with viral response.


In the cohort study, internal consistency ranged from acceptable (α = .69) to very high (α = 1.00) across time points and was quite high on average (α = .91). Across the 75 participants, there were 895 measurement occasions; of those, nonadherence was reported on only 27 occasions (3%), all of which occurred in the first 12 weeks. These 27 occasions represented 19 (26%) different individuals. At 12 weeks, 1 (1%) of patients had a detectable HCV viral load; at 12–24 weeks posttreatment, 4 (5%) had a sustained viral response. Nonadherent patients reported an average of 1.41 reasons for nonadherence.


This multi-method study established content validity of reasons for nonadherence and reliability of extent of nonadherence. High rates of adherence and viral response were consistent with previous studies using other nonadherence measurement methods.


Adherence Content validity Cognitive interviews Focus groups Qualitative research Psychometrics 



The authors would like to extend special thanks to Andrew Muir, MD MHS, and Christine Hunt, MD, for their clinical input and Jamiyla Bolton, Jahdai Dawes, Leslie Gaillard, Tina Lucas, Elizabeth Strawbridge, and Cherisa Williams for their assistance with recruitment and data collection. The views represented in this article represent those of the authors and not those of the VA or the United States Government.


Phase I of this study was supported by an investigator-initiated grant from Vertex Pharmaceuticals to Dr. Voils. Phase II of this study was funded by the Department of Medicine at Duke University Medical Center. Effort on this paper was supported by resources and facilities at the Veterans Affairs Medical Centers in Madison and Durham and by a Research Career Scientist award to Dr. Voils from the Health Services Research and Development (HSR&D) service of the Department of Veterans Affairs (VA; RCS 14-443) and a VA HSR&D Career Development Award to Dr. Gellad (CDA 14-158).

Compliance with ethical standards

Conflict of interest

Dr. Gellad is cofounder and holds equity in Higgs Boson Inc. No other author declares a conflict of interest.

Ethical standard

All procedures performed in studies involving human participants were in accordance with the ethical standards of the institutional and/or national research committee and with the 1964 Helsinki Declaration and its later amendments or comparable ethical standards.


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Copyright information

© Springer Science+Business Media, LLC, part of Springer Nature 2019

Authors and Affiliations

  1. 1.William S. Middleton Memorial Veterans HospitalMadisonUSA
  2. 2.Department of SurgeryUniversity of Wisconsin School of Medicine and Public HealthMadisonUSA
  3. 3.Center of Innovation to Accelerate Discovery and Practice Transformation (ADAPT)Durham Veterans Affairs Health Care SystemDurhamUSA
  4. 4.Department of Population and Health SciencesDuke University Medical CenterDurhamUSA
  5. 5.Department of MedicineDuke University Medical CenterDurhamUSA
  6. 6.Center for Health Equity Research and PromotionVeterans Affairs Pittsburgh Healthcare SystemPittsburghUSA
  7. 7.Division of Pharmaceutical Outcomes and Policy, Eshelman School of PharmacyUniversity of North CarolinaChapel HillUSA
  8. 8.Department of PsychiatryDuke University Medical CenterDurhamUSA
  9. 9.Center for Behavioral Cardiovascular HealthColumbia University Medical CenterNew YorkUSA
  10. 10.Duke Clinical Research InstituteDurhamUSA

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