Reporting on the level of validity and reliability of questionnaires measuring Katakori severity: A systematic review.

Objectives: Katakori is a Japanese term for non-specific symptoms including discomfort or dull pain caused by muscle stiffness around the neck through the shoulders and is one of the most frequently reported symptoms in Japan. However, there has been no standardized patient-reported outcome measure to evaluate Katakori severity. This study aimed to investigate the reporting level on validity and reliability of patient-reported outcome measures of Katakori severity.

Method: A systematic search in ICHUSHI, MEDLINE, EMBASE and PubMed was undertaken from inception to April 2017 without language limitations. Two authors independently undertook screening by inspecting the title and abstract. Inclusion criteria were as follows: (1) participants with Katakori symptoms, (2) reporting reliability or validity of questionnaire evaluating Katakori severity and (3) published journal articles. Studies that either of the authors retained through the screening process were inspected with full text by the two authors independently to examine eligibility of the study. Any disagreement on eligibility after full-text inspection was resolved by discussion between them. Methodological quality was rated with the COnsensus-based Standards for the selection of health Measurement INstruments checklist. Subsequently, the evidence level of each measurement property was assessed for each questionnaire. The two authors extracted data independently. Any disagreement was resolved by discussion between them.

Results: Five questionnaires were identified in five studies. The Shoulder Pain and Disability Index and Scale for Measuring Felt Shoulder Stiffness had the highest level of methodological quality. However, excellent measurement properties were found in only two out of nine criteria. Furthermore, in particular, content validity was not investigated in any measure.

Conclusion: There is preliminary evidence for the reliability and validity of the Shoulder Pain and Disability Index and Scale for Measuring Felt Shoulder Stiffness; however, much further research is required. Identifying or developing a patient-reported outcome measure with content validity would be a future research agenda.