How to define and measure concordance between patients' preferences and medical treatments: A systematic review of approaches and recommendations for standardization.

Objective: The purpose is to systematically review the methods used to calculate the association between patients' preferences and treatment choices and to present a set of recommendations for definition and measurement of this concept.

Methods: A systematic review of the literature from 1967 to 2007 identified articles that reported a relationship between patients' preferences and their treatment choices. Potential citations were identified from electronic databases, the Cochrane Collaborative review, and identified experts. Relevant articles were abstracted by two reviewers independently using standard forms.

Results: The search identified 3114 unique citations, the full text of 180 articles was examined, and 49 articles were included. These 49 studies used a variety of definitions of preferences and choices, and calculated concordance in different ways. Half of the studies tied their method to a theoretical framework. There were problems with many of the studies that limit the ability to generalize or make comparisons across studies.

Conclusion: There is no consistent method for defining or calculating the match between patients' preferences and treatment choices. There is a need for more clarity in the definition and reporting of this type of concordance in measures of decision quality.

Practice Implications: The match between an informed patient's preferences and treatment choices is a key component of patient-centered care. Valid and reliable measures of the level of concordance are needed.