AN IN-DEPTH REVIEW OF THE HISTORY AND USE OF THE CONTROL PREFERENCE SCALE

Purpose: We conducted an in-depth review to describe the history and use of the Control Preference Scale (CPS), the most widely used measure of patients’ preferred and actual involvement in making health care decisions.

Method: We used SCOPUS to identify articles that cited one of the ten Degner CPS studies (1988 study through the 1997 validation study).  After the removal of duplicates, we screened citations and full texts to include articles that were in English, involved healthcare decisions, and administered the CPS at more than one time point.   For relevant studies, we abstracted study characteristics (i.e., type of decision, healthcare topic) and information related to the CPS (i.e., CPS version, type of question, type of role, Degner CPS studies cited).

Result:   35 articles met our criteria.  Of the 35, the most common decision type was cancer treatment (57%), followed by cancer screening (22%), and non-cancer treatment (17%). The most common topics were breast cancer (34%) and prostate cancer (31%). The majority of the studies used the single-item version of the CPS (86%) compared to the card sort technique (14%).  About half (51%) of the studies used the CPS to measure general preferences or actual roles in health care decision-making, whereas a little over a third (37%) were focused on a specific healthcare decision. About half (48%) of the studies cited the Degner 1992 CPS study and less than half (40%) cited the 1997 validation study.

Conclusion: Most studies use a single-item version of the CPS as opposed to the original, validated card sort method.  In order to compare patient involvement across different healthcare decisions, both CPS versions must be psychometrically similar.  The adoption of the single-item version is concerning as its measurement properties are largely unknown.  The original CPS was developed to measure cancer patient involvement in treatment decisions.  However, the scale has been used to measure general and decision-specific preferences in a wide variety of healthcare contexts.  Research is needed to validate the CPS for different healthcare contexts.