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Minimum Clinically Important Difference and Patient Acceptable Symptom State of Japanese Orthopaedic Association Score in Degenerative Cervical Myelopathy Patients

Kato, So, MD; Oshima, Yasushi, MD, PhD; Matsubayashi, Yoshitaka, MD; Taniguchi, Yuki, MD, PhD; Tanaka, Sakae, MD, PhD; Takeshita, Katsushi, MD, PhD

doi: 10.1097/BRS.0000000000002928

Study Design. A retrospective analysis.

Objective. The aim of this study was to elucidate the psychometric properties of the original Japanese Orthopaedic Association (JOA) score, including the minimum detectable change (MDC), minimum clinically important difference (MCID), and patient-accepted symptom state (PASS).

Summary of Background Data. Despite the worldwide popularity of modified JOA score (mJOA), the original JOA score is still commonly used in East Asian countries, including Japan. However, unlike mJOA score, the psychometric properties of JOA score remain poorly understood.

Methods. We retrospectively reviewed a consecutive series of laminoplasty for degenerative cervical myelopathy patients in a single academic institution. Pre- and postoperative JOA scores were collected, and the recovery rate was calculated. Anchor-based methods were used to determine the cut-off values by a receiver operating characteristic (ROC) curve analysis. The patients were also asked to answer an anchor question analyzing their postoperative health transition used for the MDC and another question assessing the patient satisfaction used for the MCID and PASS.

Results. A total of 101 patients were included in the analysis. The mean preoperative JOA score was 10.3 [standard deviation (SD): 2.4), and the mean postoperative JOA score was 13.4 (SD: 2.5). The mean recovery rate was 44%. A total of 68% of the patients admitted that their health condition was at least “somewhat better” than their preoperative condition, and 66% were at least “somewhat satisfied” with the treatment results. On the basis of ROC curve analyses, the MDC and MCID for JOA score in degenerative cervical myelopathy patients were calculated to be 2.5. The PASS was estimated to be 14.5, and the MCID for JOA recovery rate was 52.8%.

Conclusion. The MDC, MCID, and PASS for JOA score for degenerative cervical myelopathy patients were reported by anchor-based ROC curve analyses.

Level of Evidence: 4

The anchor-based minimum detectable change (MDC) and the minimum clinically important difference (MCID) for JOA score in degenerative cervical myelopathy patients were calculated to be 2.5, while the patient accepted symptom state (PASS) was estimated to be 14.5. The MCID for JOA recovery rate was 52.8%.

Department of Orthopaedic Surgery, the University of Tokyo, Tokyo, Japan

Department of Orthopaedics, Jichi Medical University, Shimotsuke, Japan.

Address correspondence and reprint requests to So Kato, MD, Department of Orthopaedic Surgery, the University of Tokyo. 7-3-1 Hongo Bunkyo-ku, Tokyo 113-8655, Japan; E-mail:

Received 21 August, 2018

Revised 10 October, 2018

Accepted 17 October, 2018

The manuscript submitted does not contain information about medical device(s)/drug(s).

No funds were received in support of this work.

No relevant financial activities outside the submitted work.

Copyright © 2018 Wolters Kluwer Health, Inc. All rights reserved.