Measuring shared decision making in the consultation: a comparison of the OPTION and Informed Decision Making instruments.

OBJECTIVE: To investigate the applied and conceptual relationship between two measures of shared decision making using the OPTION instrument developed in Wales and the Informed Decision Making instrument developed in Seattle, USA using audio-taped consultation data from a UK general practice population.
METHODS: Twelve general practitioners were recruited from 6 general practices in the southwest of England. One hundred twenty-three GP-patient consultations were audio-recorded. Audiotapes were sent off to, and rated by, respective experts in the use of the OPTION and the Informed Decision Making instruments.
RESULTS: Compared to earlier work using the Informed Decision Making tool, consultations in this sample were shorter, had fewer decisions and tended to have a greater number of elements present. Similar to previous research using the OPTION, values using the OPTION instrument were low with two items, giving the patient opportunities to ask questions and checking patient understanding, exhibiting the most variability. Using a 'key' decision in each consultation as the basis for comparison, the Informed Decision Making score was not related to the overall OPTION score (Spearman's rho=0.14, p=0.13). Both instruments also predicted different 'best' and 'worst' doctors. Using a Bland-Altman plot for assessing agreement, the mean difference between the two measures was 1.11 (CI 0.66-1.56) and the limits of agreement were -3.94 to 6.16. There were several elements between the two instruments that appeared conceptually similar and correlations for these were generally higher. These were: discussing alternatives or options (Spearman's rho=0.35, p=0.0001), discussion of the patient's role in decision making (Spearman's rho=0.23, p=0.012), discussion of the pros/cons of the alternatives (Spearman's rho=0.20, p=0.024) and assessment of the patient's understanding (Spearman's rho=0.19, p=0.03).
CONCLUSION: Measures of shared decision making are helpful in identifying those shared decision making skills which may be problematic or difficult to integrate into practice and provide a tool by which the development of skills can be assessed over time. Research may implicitly place undue value on those aspects of shared decision making which are most easily measured. PRACTICE IMPLICATIONS: Shared decision making tools are a useful way of capturing the presence or absence of specific shared decision making skills and changes in skills acquisition over time. However there may be limits in the extent to which the concept of shared decision making can be measured and that more easily measured skills will be emphasised to the detriment of other important shared decision making skills.