The first accurate measure of patient participation in clinical decisions will ultimately help to determine whether this involvement improves patient outcome, say its creators. An evaluation study of its performance has already shown that general practitioners (GPs) actually share decisions with their patients much less than their positive attitude would suggest.

Mean score with the OPTION scale for patient involvement in decisions in consultations with 21 GPs on a scale of 0–100 was low (16.9 (SD 7.7) 95% confidence interval 15.8 to 18.0; minimum score 3.3, maximum 44.2). Distribution of scores was skewed towards low values.

The scale performed well in tests of validity and reliability. Within constructs measures of rater agreement within each item, agreement among raters, and homogeneity of the scale all indicated the score’s reliability. Construct validity was also demonstrated.

The scale was devised to satisfy accepted competencies for making shared decisions. It was piloted among GPs and non-clinical raters, using audiotaped simulated consultations covering a range of patient involvement, then refined in an iterative process. Its performance was judged with 186 taped routine consultations conducted by 21 GPs in the study; all were principals of one to 10 years in Gwent, South Wales, UK.

Patient autonomy and professional truthfulness are basic tenets of patient involvement in clinical decisions. There is intense interest from all sides about the potential to affect health outcome. However, outcome studies have not had the benefit of a bespoke measure of patient participation. The scale can be used for all consultations.