Capacity Assessment Instrument - Health: Pilot Study of a New Tool for Adults with Dementia.

Objectives: This research comprises a pilot study of the CAI-Health, a new tool for the evaluation of decision-making capacity in healthcare. It aims to analyze the instrument's indicators of reliability and internal validity to conclude its final version.

Methods: A total of 89 participants were included, of which 22 had Alzheimer's Disease; 32 had mild cognitive impairment, and 35 were controls. Cronbach's alpha and the intercorrelation matrix were used as indicators of reliability and internal validity as well as to identify items for elimination. Repeated-measures ANOVA allowed for the analysis of differences between the vignettes that comprise CAI-Health.

Results: The internal consistency results were acceptable, and no items were proposed for elimination. A repeated-measures ANOVA revealed that the vignettes were unexpectedly equivalent. Despite the procedures used to develop clinical vignettes with increased levels of complexity in assessing decision-making capacity, this study showed no differences in the vignettes' level of demand.

Conclusions: The extensive application of CAI-Health compromises its clinical usefulness and viability. To reduce its length while maintaining a thorough assessment of each ability, it was decided to eliminate two vignettes and retain all interview items. The final version of the CAI-Health comprises a clinical vignette and a capacity interview.

Clinical implications: CAI-Health was designed for the assessment of medical decision-making capacity in older adults.