Psychometric analysis and critical appraisal of the original, revised, and modified versions of the Japanese Orthopaedic Association score in the assessment of patients with cervical spondylotic myelopathy

OBJECTIVE Cervical spondylotic myelopathy (CSM) is the most common cause of nontraumatic spinal cord impairment and disability in the world. Given that the Japanese Orthopaedic Association (JOA) score is the most frequently used outcome measure in clinical research and practice for treating patients with CSM, this review was undertaken to comprehensively and critically evaluate the psychometric properties of the JOA score. METHODS The authors identified studies (published in the period of January 1975 to November 2015) on the psychometric properties of the original, revised, and modified versions of the JOA score in Medline, PsycINFO, Excerpta Medica dataBASE (EMBASE), American College of Physicians Journal Club, and Cochrane Database of Systematic Reviews. Additional publications were captured in a secondary search of the bibliographies in both original research articles and literature reviews identified in the original search. The JOA scores were evaluated for item generation and reduction, internal consistency, reliability, validity, and responsiveness. This review included all those versions of the JOA score whose psychometric properties had been reported in at least 2 published studies. RESULTS The primary search strategy identified 59 studies, of which 9 fulfilled the inclusion and exclusion criteria. An additional 18 publications were captured in the secondary search and included in the analysis. The key findings from the 27 studies analyzed indicated the following: 1) the original JOA score (1975) was the source for the revised JOA score (1994) and 3 modified versions (1991, 1993, and 1999 JOA scores) reported or used in at least 2 published studies; 2) the revised and modified versions of the JOA score are markedly different from each other; 3) only the revised JOA score (1994) was validated with the original JOA score; and 4) the 1975 JOA score is the most appropriate instrument for assessing patients in Asian populations (especially from Japan) because of its psychometric attributes, and the 1991 JOA score is the most appropriate version for use in Western populations. CONCLUSIONS The authors' results indicate that the original (1975), revised (1994), and modified (1991, 1993, and 1999) versions of the JOA score are substantially different from each other in terms of their content and have been incompletely examined for their psychometric properties and cultural sensitivity. Whereas the 1975 JOA score is the most appropriate version for assessing individuals from Asian populations (particularly those eating with chopsticks), the 1991 JOA score is most suitable for evaluating patients in Western populations. Nonetheless, further investigation of the psychometric properties of the 1975 and 1991 JOA scores is recommended because of a paucity of studies reporting on the responsiveness of these 2 scoring instruments.