Reliability of the Australian Therapy Outcome Measures for Occupational Therapy (AusTOMs-OT).

BACKGROUND/AIM: The delivery of evidence-based health care requires the routine adoption of outcome measures that are valid and reliable. The Australian Therapy Outcome Measures for Occupational Therapy (AusTOMs-OT) was developed in Australia to capture a global snapshot of status for any client, and has preliminary psychometric evidence to support use. Building on the psychometric evidence of the AusTOMs-OT will provide therapists and researchers with further information as to how best to apply the AusTOMs-OT in their field. This study reports on the reliability of the 12 AusTOMs-OT scales, which are each scored on the four domains of Impairment, Activity Limitation, Participation Restriction and Distress/Wellbeing.

METHODS: A total of 31 occupational therapists rated 12 written case studies on two occasions, separated by two weeks. Test-retest reliability, inter-rater reliability, intra-rater reliability (using intra-class correlation coefficients (ICCs)) and measurement error were calculated, in line with the COnsensus-based guidelines for the Selection of health Measurement Instruments (COSMIN).

RESULTS: The ICCs for inter-rater reliability for all domains for all scales ranged from 0.531 to 0.922 suggesting moderate to very high reliability. Therapist intra-rater reliability ranged from ICC 0.675 to 1.000, suggesting moderate to high consistency. The stability of the scales was demonstrated with test-retest ICCs coefficients ranging from 0.616 to 0.960. The measurement error was found to be below 0.5 point for all scales and domains except for Scale 1, Impairment (just over at 0.604) and similarly the error range for each scale was also all below 1 point except Scale 1, Impairment.

CONCLUSION: The AusTOMs-OT scales possess moderate to very high reliability across the 12 scales. Occupational therapists can continue to use AusTOMs-OT with confidence with all clients to establish global outcomes and to build evidence to underpin practice.