Comparability of Mayo-Portland Adaptability Inventory ratings by staff, significant others and people with acquired brain injury

Objectives: To determine the internal consistency, reliability and comparability of the Mayo-Portland Adaptability Inventory (MPAI-4) and sub-scales completed by people with acquired brain injury (ABI), family and significant others (SO) and rehabilitation staff. Subjects: 134 people with ABI consecutively seen for outpatient rehabilitation evaluation. Method: MPAI-4 protocols based on independent ratings by the people with ABI undergoing evaluation, SO and rehabilitation staff were submitted to Rasch Facets analysis to determine the internal consistency of the overall measure and sub-scales (Ability, Adjustment and Participation indices) for each rater group and for a composite measure based on all rater groups. Rater agreement for individual items was also examined. Results: Rasch indicators of internal consistency were entirely within acceptable limits for 3-rater composite full scale and sub-scale measures; these indicators were generally within acceptable limits for measures based on a single rater group. Item agreement was generally acceptable; disagreements suggested various sources of bias for specific rater groups. Conclusions: The MPAI-4 possesses satisfactory internal consistency regardless of rating source. A composite measure based on ratings made independently by people with ABI, SO and staff may serve as a 'gold standard' for research purposes. In the clinical setting, assessment of varying perspectives and biases may not only best represent outcome as evaluated by all parties involved but be essential to developing effective rehabilitation plans.