Study design: Prospective cohort study.
Objective: To evaluate the postoperative responsiveness of the Chinese versions of the Japanese Orthopaedic Association Cervical Myelopathy Evaluation Questionnaire (JOACMEQ) and the Neck Disability Index (NDI) in a cohort of patients with cervical spondylotic myelopathy.
Summary of background data: We have recently completed the translation and cross-cultural adaptation of a Chinese version of JOACMEQ. However, the postoperative responsiveness of the Chinese JOACMEQ and how it compares with the more commonly used NDI remain undetermined.
Methods: Forty-five patients with cervical spondylotic myelopathy undergoing surgical decompression were recruited. All patients completed the Chinese JOACMEQ and the NDI preoperatively and again at 3-month follow-up together with an 11-point Global Rating of Change scale. Patients were dichotomized either as "Improved" or "Stable" on the basis of Global Rating of Change. Paired t test, standardized effect sizes, and Guyatt responsiveness index were used to determine internal responsiveness. External responsiveness was evaluated by the area under the receiver operating characteristic curve and the minimal clinically important change was determined as the optimal cutoff point for patient discrimination anchor-based on Global Rating of Change classification.
Results: Bladder function and quality of life (QOL) domains (P < 0.03) of the JOACMEQ and the NDI (P = 0.004) reached statistically significant difference with the paired t test. After the dichotomization, the standardized effect size was strong for the QOL domain in the improved group (0.85) and the Cervical spine function (0.97) in the stable group, respectively. Based on the Guyatt responsiveness index, strong responsiveness was found for the Bladder function (0.88) and QOL (0.76) domains of the JOACMEQ and moderate responsiveness (0.55) for the NDI. The Bladder function (area = 0.82; minimal clinically important change = 6) and QOL (0.83; minimal clinically important change = 8.5) also produced largest area under the receiver operating characteristic curve.
Conclusion: Bladder function and QOL domains of the JOACMEQ seem to demonstrate the strongest postoperative responsiveness and thus may be more appropriate than NDI when attempting to determine treatment efficacy in cervical spondylotic myelopathy.
Level of evidence: 3.