The OPTION scale for the assessment of shared decision making (SDM): methodological issues

Background: Promoting patient involvement in medical decision making has become a desirable goal in medical consultations. Reliable and valid measures are necessary to evaluate interventions designed to promote shared decision making and to understand determinants and associations. The OPTION ("observing patient involvement'') scale is the most prominent observation instrument for assessing the extent to which clinicians actively involve patients in decision making. Objective: This paper discusses psychometric and methodological characteristics of the OPTION scale. Results: There is little support for the purported unidimensional structure. Although reliabilities are acceptable, results are highly heterogeneous across studies. There is also little evidence concerning validity. In particular, studies mainly failed to support convergent validity. Additional issues pertain to lack of item independence, restriction of range, and failure to consider dyadic aspects. Conclusions: Given these findings, a number of methodological and conceptual issues still need to be addressed for the effective measurement of patient involvement. Directions for future research are discussed.