The nine-item Shared Decision Making Questionnaire (SDM-Q-9) is one of the most frequently
applied instruments for assessing patients' involvement in medical decision-making.
Our objectives were to develop a Hungarian version of SDM-Q-9, to evaluate its psychometric
properties and to compare its performance between primary and specialised care settings.In
2019, a sample of adults (n = 537) representative of the Hungarian general population
in terms of age, gender and geographic region completed an online survey with respect
to a recent health-related decision. Outcome measures included SDM-Q-9 and Control
Preferences Scale-post (CPSpost). Item characteristics, internal consistency reliability
and the factor structure of SDM-Q-9 were determined.The overall ceiling and floor
effects for SDM-Q-9 total scores were 12.3% and 2.2%, respectively. An excellent internal
consistency reliability (Cronbach's alpha 0.925) was demonstrated. Exploratory factor
analysis resulted in a one-factor model explaining 63.5% of the variance of SDM-Q-9.
A confirmatory factor analysis supported the acceptability of this model. Known-groups
validity was confirmed with CPSpost categories; mean SDM-Q-9 total scores were higher
in the 'Shared decision' category (72.6) compared to both 'Physician decided' (55.1,
p = 0.0002) and 'Patient decided' (57.2, p = 0.0086) categories. In most aspects of
validity and reliability, there was no statistically significant difference between
primary and specialised care.The overall good measurement properties of the Hungarian
SDM-Q-9 make the questionnaire suitable for use in both primary and specialised care
settings. SDM-Q-9 may be useful for health policies targeting the implementation of
shared decision-making and aiming to improve efficiency and quality of care in Hungary.
