Treatment preference, adherence and outcomes in patients with cancer: literature review and development of a theoretical model

Abstract

Objective:

A patient’s preference may guide their behavior and influence their willingness to take medication or undergo treatment affecting outcomes, such as health-related quality of life, or survival. The importance of understanding patient preferences within oncology is unclear and few adherence studies exist compared with other therapeutic areas.

Research design and methods:

This study was designed to review the literature regarding patient preferences, adherence and their link to outcomes specifically in the oncology setting and to propose a theoretical model. An in-depth review was conducted, using Embase, MEDLINE and Cochrane Library databases to search for published data examining patient preference, adherence and oncology-specific outcomes, from 1982–2012. Articles were reviewed independently by two authors and rated for relevance and quality. Information from high-quality articles and discussion with oncology and patient preference experts were used to identify associations between important individual concepts as a basis for a theoretical model.

Results:

In total, 1362 abstracts were identified. After removal of duplicates and initial review, 1269 were excluded and 93 reviewed in detail. Of these publications, 18 were deemed ‘high-quality’ and used to develop the final model. Variables associated with patient preference, adherence and outcome were identified. External variables included communication, treatment and mode of administration; patient beliefs and values were identified as cognitive variables; and adherence was attributed as a behavioral variable. Relationships between patient preference, adherence and clinical outcomes were established. Adverse events had a strong relationship with adherence; patient beliefs and values were identified as having a moderating effect on adherence. Adherence behavior had a direct relationship to outcomes.

Conclusions:

Improving our understanding of patient preference may improve clinical outcomes in oncology patients. Although the proposed theoretical model is limited, it provides a basis to develop testable hypotheses for the relationships between patient preference, adherence and outcomes specific to oncology.

Keywords::

• Adherence
• Oncology
• Outcomes
• Patient preference
• Theoretical model

Transparency

Declaration of funding

This work was supported by the GlaxoSmithKline group of companies.

Declaration of financial/other relationships

J.A.C. has disclosed that she is a consultant to GSK. S.L.S. and A.J.L. have disclosed that they are employees of ICON plc, who were paid a fixed fee for designing and undertaking this research, and analyzing and reporting the findings. B.M.B. has disclosed that he was also employed by ICON plc between January 2012 and September 2013. A.T. has disclosed that he was paid a fixed fee by ICON plc for contributing to the research and analysis. C.T. has disclosed that he has no significant relationships with or financial interests in any commercial companies related to this study or article.

CMRO peer reviewers on this manuscript have received an honorarium from CMRO for their review work, but have no relevant financial or other relationships to disclose.

Acknowledgments

David Griffiths PhD, on behalf of Fishawack Indicia Ltd, provided medical writing services, funded by GlaxoSmithKline. Leticia Barcena of ICON plc (Health Economics Department) acted as a systematic reviewer to provide input regarding literature search strategies.