Objective: To examine the psychometric properties of a revised scale, named 'observing patient involvement in decision making' (OPTION), by analysing its reapplication to a sample of routine primary care consultations. The OPTION instrument assesses to what degree clinicians involve patients in decision making.
Design: Cross-sectional assessment of medical interaction by two calibrated raters.
Setting: Primary care.
Participants: Twenty-one general practitioners provided 186 consultations for assessment.
Measurements: Observational score using the OPTION instrument.
Results: Compared with the first version of the OPTION scale, the revised scale that uses a magnitude instead of an attitude scale, when applied to the same data set, resulted in improvement in the scale's reliability and to lower scores for the levels of involvement achieved by the practitioners. Factor analysis confirms that it is acceptable to regard the scale as a single construct. Although there is moderate variability when raters are assessed on an item by item basis, the agreements between raters at the level of the overall OPTION score is high (the intraclass correlation coefficient scores for total OPTION score was 0.77), a level that is acceptable for the evaluation of a set of consultations per practitioner (e.g. between 5 and 10 consultations), where aggregate scores would be used for determining overall performance.
Conclusions: We conclude that OPTION is sufficiently reliable to be used for formal assessment at the level of the whole instrument (all 12 items).