ABSTRACT
Background: dementia is a common cause of altered decision-making capacity. Determining whether an individual has the ability to make a specific decision can be very challenging for both clinicians and researchers. The UK legislation requires that we both promote residual capacity where possible, and protect vulnerable adults who cannot make independent decisions. We evaluated published instruments designed to aid in the assessment of capacity, focussing on those meeting the UK legal requirements. We also consider further disease and culture-specific factors which may influence decision making. Methods: a search of electronic databases was made for articles published between 2000 and 2017 detailing structured tools for the assessment of mental capacity. These were evaluated against the UK legal requirements. Results: nine tools were identified which fulfilled the UK legal requirements. Their design and structure varied, as did the level of reliability and validity data available. Some instruments can be tailored for a specific decisional scenario, whilst others are designed for use by particular patient groups. Discussion: a wide range of mental capacity assessment instruments is available, but not all fulfil the UK legal requirements. Healthcare professionals and researchers should be mindful of personal, cultural and disease-specific factors when assessing capacity. No gold standard for capacity assessment exists, which hampers the evaluation of different approaches. A combination of the opinion of a healthcare professional or researcher trained in capacity evaluation, plus the use of a structured assessment tool is the most robust approach.
