title: 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.
  
  
  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.
authors.affiliation: ICON plc , Oxford , UK.
authors.forename: Sarah L
authors.initials: SL
authors.lastname: Shingler
authors.forename: Bryan M
authors.initials: BM
authors.lastname: Bennett
authors.forename: Joyce A
authors.initials: JA
authors.lastname: Cramer
authors.forename: Adrian
authors.initials: A
authors.lastname: Towse
authors.forename: Christopher
authors.initials: C
authors.lastname: Twelves
authors.forename: Andrew J
authors.initials: AJ
authors.lastname: Lloyd
mesh_terms: D005260:Female; D006801:Humans; D008297:Male; D008962:Models, Theoretical; D009369:Neoplasms / Q000523:psychology* / Q000628:therapy*; D010349:Patient Compliance; D057240:Patient Preference; D011788:Quality of Life; D016896:Treatment Outcome
keywords: Adherence; Oncology; Outcomes; Patient preference; Theoretical model