Introduction

The members of the Subcommittee on Evaluation for Low Back Pain and Cervical Myelopathy, who belong to the Clinical Outcomes Committee of the Japanese Orthopaedic Association, have composed a new selfadministered questionnaire as an outcome measure for patients with cervical myelopathy1 to solve problems of the Japanese Orthopaedic Association score (JOA score) proposed by the Japanese Orthopaedic Association in 1975,2 which was revised in 1994.3 The features of this new outcome measure are that the outcomes are not influenced by the examiner because it is a self-administered questionnaire, and that it results in possible evaluation of the functional capacity of the cervical spine, the physical function of the upper and lower extremities, and bladder function, which might be disturbed by cervical myelopathy, and health-related quality of life (QOL). In Part 1, the authors performed a primary survey on healthy volunteers and patients with cervical myelopathy and statistically analyzed the responses to the questionnaire. The authors extracted 24 questions, which consisted of 13 questions with regard to the physical functions of the cervical spine and the spinal cord and 11 questions derived from the Medical Outcome Study Short-Form 36-Item Health Survey (SF-36, Japanese version),4 respectively (Table 1). In question C-41 (“Can you turn your head when you back your car?”), approximately 22% of the patients and 10% of the normal volunteers responded “I am not sure” or “I do not drive”. Because some older patients no longer drive a car, the authors devised an alternative question to C-41, “While in the sitting position, can you turn your head toward the person who is seated behind you and speak to him/her while looking him/her in the face?” The purposes of the present study were to perform a secondary survey on patients with cervical myelopathy and to statistically analyze the responses to validate this new JOA Cervical Myelopathy Evaluation Questionnaire (JOACMEQ), which consisted of 24 items, and also to examine if it is possible to convert item C-41 to the alternative question.

Table 1 Twenty-four items and one alternative remained as candidates for the questionnaire
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Methods

The Clinical Outcomes Committee of the Japanese Orthopaedic Association conducted this study together with eight university hospitals and their affiliated hospitals from November 2002 to April 2003 to develop an objective tool to measure outcomes in patients with cervical myelopathy. Another purpose of this study was to verify if question C-41-2, “While in the sitting position, can you turn your head toward the person who is seated behind you and speak to him/her while looking him/her in the face?”, can replace C-41 without disturbing the reliability of the questionnaire. A member of the Subcommittee on Low Back Pain and Cervical Myelopathy Evaluation from each hospital administered the questionnaire to more than 50 patients with cervical myelopathy in each hospital. The questionnaire consisted of 25 questions, 24 of which were extracted in the primary survey (Table 1).

Survey of patients with cervical myelopathy

Patients answered each question by themselves. This study included patients with cervical myelopathy secondary to cervical disc herniation, spondylosis, and ossification of the posterior longitudinal ligament. Among these patients, only patients whose clinical symptoms were likely to be unchanged during the course of the survey were finally included. Patients with the following disorders were excluded: cervical spondylotic amyotrophy, cervical radiculopathy, disorders of the upper cervical spine such as atlantoaxial subluxation, spine and spinal cord tumors, vascular lesions of the cervical spinal cord, syringomyelia, multiple sclerosis, motor neuron disease, myelitis, and spinal cord injury. Patients with disturbances of the central nervous system, such as cerebral infarction, combined cervical and thoracic spine lesion, orthopedic disorders except cervical myelopathy, and cognitive disorders, and patients who could not complete the questionnaire because of defects of the arm, fingers, or foot, were also excluded. Patients whose condition resulted from occupational or traffic accidents were excluded. Patients who had a surgical history of cervical spine surgery and those who participated in the primary survey were also excluded. All patients were asked to participate in the second survey and were told that the questionnaire would be used to develop a new JOACMEQ. Only patients who agreed to join the study answered the questionnaire.

Analysis of the distribution of answers to the questionnaire

The distribution of answers to the questionnaire was analyzed. In Part 1, the authors excluded a question for which 80% of the answers were concentrated on one choice. In the present study, the authors reevaluated if there was a question in which the answer concentrated on one option. Reliability of this questionnaire as an outcome measure for patients with cervical myelopathy was verified.

Endorsement of the alternative question

The authors examined if it was possible to convert the question C-41 to the alternative question C-41-2. For statistical analysis, data were analyzed using STATISTICA for Windows (1988) (StatSoft, Tulsa, OK, USA) and SPSS software (version 12; Chicago, IL, USA). The κ coefficient and Spearman’s correlation coefficient were calculated to detect the correlation between the two questions.5 P < 0.05 was considered significant. According to the results of the statistical analysis, the authors finalized the questionnaire as an outcome measure for patients with cervical myelopathy.

Results

Three hundred and sixty-eight patients with cervical myelopathy were enrolled in the present study. The patients comprised 247 men and 121 women. Cervical myelopathy was secondary to a herniated disc in 52 patients, spondylosis in 239 patients, ossification of the posterior longitudinal ligament in 76 patients, and combined disorders in 1. Table 2 shows the age and sex distribution of patients. The authors then excluded individuals with other orthopedic disorders, giving a total of 333 patients whose data were analyzed.

Table 2 Demographic data in the primary survey
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The distribution of the revised JOA score,3 shown in Table 3, revealed that patients with mild to severe myelopathy were involved in the present study. The distribution of this patient group was not anomalous as a group of patients with cervical myelopathy.

Table 3 The distribution of revised Japanese Orthopaedic Association (JOA) scores
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Table 4 shows the distribution of the answers for the questionnaire. No questions elicited no answer or “I am not sure” in more than 5% of patients except question C-41. There were no questions that the patients answered with difficulty. For question C-41 (“Can you turn your head when you back your car?”), more than 30% of patients responded “I am not sure. I do not drive a car/I do not drive these days” or “no answer.” There was no tendency for concentration on one option as an answer to questions. The distribution of the answers to question C-41 and the alternative question for C-41 (C-41-2) was analyzed. Table 5 shows the distributions of answers to these two questions by patients with cervical myelopathy. When the choice of “no answer” and “I am not sure” were excluded for statistical analysis, Spearman’s correlation coefficient and κ value were 0.795 and κ 0.630, respectively. These results indicated that there was a high correlation between questions C- 41 and C-41-2. In one hundred five patients who chose “no answer” or “I am not sure” as the answer to question C-41, 50 patients answered “I can do it with some effort” to question C-41-2. In patients who responded “I cannot do it” or “I can do it without difficulty” as an answer to question C41-2, there was high agreement in the distribution of the answers to question C-41. However, the agreement in patients who responded “I can do it with some effort” as an answer to questions C-41 and C-41-2 was relatively low.

Table 4 The distribution of answers to residual 24 questions and 1 alternative question
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Table 5 The distribution of answers to question C-41 and the alternative question (C-41-2)
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Collectively, it was possible to convert question C-41 to the alternative question C41-2. A final questionnaire as an outcome measure for patients with cervical myelopathy consisted of 24 questions, which consisted of 13 items from the questions about the physical functions of the cervical spine and the spinal cord and 11 items from SF-36.

Discussion

The authors statistically selected questions to evaluate the physical function of the cervical spine and spinal cord and health-related QOL, and finally composed a questionnaire, which consisted of 24 questions, as an outcome measure for patients with cervical myelopathy.1 In the present study, the authors found that there were no questions for which the distribution of answers was concentrated on one option, and that the distribution of the answers was not statistically different from those obtained in Part 1, with the exception of question C-41. These results suggest that the questionnaire has sufficient reliability for clinical use. With regard to the distribution of answers for question C-41, the authors found in Part 1 that approximately 22% of patients responded “I am not sure” or “I do not drive”,1 whereas in the present study, more than 30% of patients responded “I am not sure”, “I do not drive a car/I do not drive these days”, or “no answer.” Therefore, this question was not reliable as a question to evaluate the physical function of the cervical spine. The authors then devised the alternative question C-41-2 and statistically evaluated if it was possible to convert question C-41 to question C-41-2. As a result, it was determined that question C-41 could be exchanged with the alternative question, C-41-2.

As a statistical analysis, it is often the case that the κ coefficient is used for a test of coincidence if true and/or alternative values are categorical values. To demonstrate the coincidence, the value of the κ coefficient should be at least 0.4 or more, and preferably more than 0.6.4 In the present study, the authors found that κ value coincidence between questions C-41 and C-41-2 was more than 0.6. This result indicated that question C-41-2 is acceptable in place of question C-41.

The authors then finalized the self-administered questionnaire, which consists of 24 questions with regard to cervical spine function, motor functions of the upper and lower extremities, bladder function, and health-related QOL. Phraseology, such as words, language, and phrasing, was examined and modified by conference with the medical specialists’ group, and the questionnaire was finally completed.

Most Japanese orthopedic spine surgeons have evaluated the severity of cervical myelopathy using the conventional JOA score, in which the points can be calculated.2,3 Especially in the clinical situation, it is very easy to examine the recovery of neurological function in patients with cervical myelopathy after conservative and/or surgical treatments because of this scoring system. Therefore, it is desirable to statistically establish a scoring system using this new questionnaire, JOACMEQ. In addition, it is important to evaluate whether the JOACMEQ measures the outcomes for all patients with cervical myelopathy in whom the symptoms are mild to severe. Therefore, the authors must verify whether this questionnaire can measure severity of cervical myelopathy. Because there is no standard value for this questionnaire, appropriate statistical analyses such as factor analysis to consolidate the information are needed. In addition, considering the clinical use of this questionnaire, reliability or reproducibility of the questionnaire should be verified by two investigations at different time points. Responsiveness of this questionnaire also must be evaluated by undertaking surveys before and after specific medical treatments.

The members of the Subcommittee on Low Back Pain and Cervical Myelopathy Evaluation hope that this questionnaire prevails and becomes a global standard to evaluate outcomes in patients with cervical myelopathy.