Development of the Working Alliance Inventory-Short Form Japanese version through factor analysis and test–retest reliability

ABSTRACT

Background: Working alliance between the physiotherapist and patient is important for successful treatment in physiotherapy. Working alliance can be measured by a 12-item self-reporting measure with 7-point Likert scale, the Working Alliance Inventory Short-Form Client (WAI-SC). Objectives: To develop a shorter version of the Japanese WAI-SC through examination of factor structure and test–retest reliability. Design: Survey. Method: A convenience sample of 118 outpatients with musculoskeletal disorders completed the WAI-SC immediately after the third consultation and 101 of them completed the WAI-SC immediately before the fourth consultation. Results/findings: Through investigations of internal consistency, test–retest reliability, and factor structure, a single structure was detected by excluding Item 4 and Item 10. Score calculation was also modified to dichotomous variables (Score 7 or other scores) due to serious ceiling effects, where >50% of responses were Score 7. A five-item questionnaire with dichotomous score rating (Modified WAI-SC Japanese musculoskeletal version) was developed through consideration of internal consistency and item-total correlation analysis. This questionnaire demonstrated adequate internal consistency (Cronbach’s α = 0.88) and excellent test–retest reliability for each item (Cohen’s κ for all > 0.4) and total scores (intraclass correlation coefficient = 0.84). Conclusions: The five-item Modified WAI-SC Japanese musculoskeletal version was developed with a single factor structure showing adequate internal consistency and excellent test–retest reliability.

KEYWORDS:

• Factor analysis
• Japanese language
• musculoskeletal disorders
• reliability
• short form
• working alliance

Acknowledgments

The authors wish to acknowledge Dr. Satoru Aoki and Aoki Chuo Clinic; Mr. Takashi Takagi and Sapporo Kiyota Orthopaedic Hospital; Mr. Ryuichi Sugiyama and Suzuki Clinic Orthopaedics River City; and Dr. Takaya Narita, Mr. Yuta Orikasa, Mr. Eiji Yamazaki, Mr. Toru Yaguchi, Mr. Takeshi Tezuka, and Mr. Hiroki Sugiyama and Sasamoto Orthopaedic Hospital for assistance of data collection.

Declaration of interest

The authors declare no conflict of interest.