Title

Reliability of the Adult Myopathy Assessment Tool in individuals with myositis

ORCiD

Davenport: 0000-0001-5772-7727

Document Type

Article

Publication Title

Arthritis Care & Research

ISSN

2151-464X

Volume

67

Issue

4

DOI

10.1002/acr.22473

First Page

563

Last Page

570

Publication Date

4-1-2015

Abstract

Objective: The Adult Myopathy Assessment Tool (AMAT) is a 13-item performance-based battery developed to assess functional status and muscle endurance. The purpose of this study was to determine the intrarater and interrater reliability of the AMAT in adults with myositis.

Methods: Nineteen raters (13 physical therapists and 6 physicians) scored videotaped recordings of patients with myositis performing the AMAT for a total of 114 tests and 1,482 item observations per session. Raters rescored the AMAT test and item observations during a follow up session (mean SD 19 6 days between scoring sessions). All raters completed a single, self-directed, electronic training module prior to the initial scoring session.

Results: Intrarater and interrater reliability correlation coefficients were 0.94 for the AMAT functional subscale, endurance subscale, and total score (all P < 0.02 for H-o, 0.75). All AMAT items had satisfactory intrarater agreement (kappa statistics with Fleiss-Cohen weights, with values (w) = 0.57-1.00). Interrater agreement was acceptable for each AMAT item ( = 0.56-0.89) except the sit up ( = 0.16). The standard error of measurement and 95% confidence interval range for the AMAT total scores did not exceed 2 points across all observations (AMAT total score range 0-45).

Conclusion: The AMAT is a reliable, domain-specific assessment of functional status and muscle endurance for adult subjects with myositis. Results of this study suggest that physicians and physical therapists may reliably score the AMAT following a single training session. The AMAT functional subscale, endurance subscale, and total score exhibit interrater and intrarater reliability suitable for clinical and research use.