Reliability and validity of the German version of the OPTION scale.

Objective: To examine the psychometric properties of the German version of the 'observing patient involvement' scale (OPTION) by analysing video recordings of primary care consultations dealing with counselling in cardiovascular prevention.

Design: Cross-sectional assessment of physician-patient interaction by two rater pairs and two experts in shared decision making (SDM).

Setting: Primary care.

Participants: Fifteen general practitioners provided 40 videographed consultations.

Measurements: Video ratings using the OPTION instrument.

Results: Mean differences on item level between the four raters were quite large. Most items were skewed towards minimal levels of shared decision making. Measures of inter-rater association showed low to moderate associations on item level and high associations on total score level. Cronbach-α of the whole scale based on the data of all four raters is 0.90 and therefore on a high level. An oblique factor analysis revealed two factors, but both factors were highly correlated so we can confirm a one-dimensional structure of the instrument. ROC analyses between the rater total scores and dichotomized expert ratings (SDM yes/no) revealed a good discriminability of the OPTION total score. Physicians with more expertise in shared decision making received higher OPTION ratings.

Conclusions: The German version of the OPTION scale is reliable at total score level. Some items need further revision in the direction of more concrete, observable behaviour. We were only able to perform a quasi-validation of the scale. Validity issues need further research efforts.