Introduction

As described in Part 11 and Part 2,2 the Japanese Orthopaedic Association (JOA) decided to revise the assessment tools for cervical myelopathy and develop a new JOA Cervical Myelopathy Evaluation Questionnaire (JOACMEQ). The point of the revision was to make it: (1) more scientific from the standpoint of medical statistics, and (2) more patient-oriented. For the first- and second-round surveys, the committee created a new questionnaire of 77 items including SF-36 (the Medical Outcome Study Short-Form 36-Item Health Survey)3 to assess health-related quality of life (HRQOL) and 41 items to assess functioning of the cervical spinal cord and cervical spine. In these surveys, 53 items were excluded.1,2 The purpose of this study (the third-round survey A) was to confirm the reproducibility of the selected 24 questions written in Japanese (see Appendix). The questionnaire was self-administered, so interobserver reliability did not need to be confirmed. To examine the reliability of the questionnaire, only test-retest reliability was evaluated.

Materials and methods

Inclusion criteria were as follows: (1) Patient had to have cervical myelopathy secondary to cervical disc herniation, cervical spondylosis, or ossification of the posterior longitudinal ligament (OPLL); and (2) there was no change of symptoms between the two interviews, which was judged by attending surgeons. Exclusion criteria included (1) patient had other musculoskeletal disease requiring medical treatment; (2) patient had a mental disease and so could potentially furnish inappropriate answers; (3) patient was postoperative; 4) patient had participated in the former surveys.

We asked 460 Japanese board-certified spine surgeons to participate in the survey between January 2004 and June 2004. Patients were recruited from the outpatient clinic of each surgeon during the planned inquiry period. Self-assessment was used in this study. Each patient was interviewed using the same questionnaire twice at an interval of 4 weeks (±3 days). The attending surgeon filled out the patient’s information regarding the diagnosis and the presence or absence of concomitant diseases and judged the severity using a three-step rating scale (mild, moderate, severe). This study was approved by the Ethics Committee of the Japanese Society for Spine Surgery and Related Research, and informed consent was obtained from each patient.

The reliability of the questionnaire was evaluated by determining the extension of the weighted kappa coefficients. According to the most widely accepted criteria proposed by Landis and Koch, a kappa coefficient of ≥0.4 was judged reliable.4 The 95% confidence intervals were calculated for all reliability coefficients.

All statistics were calculated using SPSS software (version 12; SPSS, Chicago, IL, USA).

Results

Of 304 patients who participated in this survey, 103 were excluded owing to a change of symptoms between the two interviews or an inappropriate patient administration interval, leaving 201 available for the study (74 women, 127 men). The mean ± SD patient age was 63.8 ±12.8 years (Table 1). The diagnosis was cervical disc herniation in 29, cervical spondylotic myelopathy in 113, and OPLL/other in 59. Table 2 lists the severity of patient myelopathy evaluated by the current JOA scoring system and shows that the characteristics of the recruited patients were not specific. The distribution of answers for each item during the second interview is shown in Table 3, and neither ceiling nor floor effects were observed. The results for test-retest reliability are shown in Table 4. The weighted kappa coefficient for each item was >0.4, showing that the test-retest reliability of JOACMEQ was acceptable. Among the three groups with severity judged as mild, moderate, or severe, there was some difference in the weighted kappa coefficient for some items, but the difference was statistically not significant. The difference among the three diseases (cervical disc herniation, cervical spondylosis, OPLL) was also statistically not significant (data not shown).

Table 1 Baseline participant demographics (n = 201)
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Table 2 Distribution of the severity evaluated by the current JOA scoring system
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Table 3 Distribution of answers for each item in the second interview
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Table 4 Reproducibility of each item
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Discussion

Measurements of the outcome of cervical myelopathy must have sufficient reliability and validity and should be proven by means of statistical evaluation. The current JOA scoring system for cervical myelopathy has been widely used but has not been shown to meet such a requirement.5,6 A manner of measuring patient-based outcome has also been regarded as essential for evaluating a patient’s health status. We sought to develop a new questionnaire using a psychometric method. The newly proposed document, which is self-administered and disease-specific, includes function of the cervical spinal cord and cervical spine as well as health-related quality of life. The first- and second-round surveys selected 24 of 77 items after repeated discussions among the subcommittee members.1,2

In this third survey, we succeeded in confirming the reliability of the 24 items. The next steps are to check the validity of the questionnaire, perform a factor analysis to determine the underlying cluster of the question naire items, complete the measurement scale, and confirm the responsiveness of the questionnaire.

Conclusion

The newly developed JOA Cervical Myelopathy Evaluation Questionnaire (JOACMEQ) was proven to be sufficiently reliable.