Structural validity and internal consistency of an ecological observation-based assessment, the Activities of Daily Living Profile.

INTRODUCTION

Direct observation of everyday task performance is considered the most accurate measure of independence for individuals with executive function impairments. However, few observation-based measures have been shown to have sound psychometric qualities and be clinically applicable. The objective of this study was to investigate the Activities of Daily Living (ADL) Profile's structural validity using exploratory factor analyses and internal consistency in order to identify the minimum set of tasks required to achieve reliable scores in each of three ADL environments (personal, home and community).

METHODS

Ninety-one persons with a severe traumatic brain injury aged 16-40 years (convenience sample) were recruited from a university affiliated level 1 trauma hospital. The 17 observation-based tasks of the ADL Profile were administered by one of five occupational therapists, either in the hospital or in the subjects' home and community environments. This measure of independence considers goal formulation, planning, carrying out and verifying goal attainment.

RESULTS

Exploratory factor analysis indicated the unidimensionality of the 17 tasks of the ADL Profile. A single factor explained more than 80% of the common variation, which in this case is the concept of independence. Internal consistency of task scores is very high (0.955), suggesting redundancy of the tasks. Approaches used to reduce the number of items, and to optimise the clinical applicability of the tool, showed that a minimum of two tasks per each of three environments (personal, home, community) is required to obtain reliable results that respect the tool's internal structure. Each assessment should contain both simple and familiar and more novel and complex tasks.

CONCLUSIONS

Findings show that the ADL Profile is a valid and clinically applicable observation-based measure of independence that considers four important task-related components: goal formulation, planning, carrying out and verifying goal attainment.