(I-504) A Clinical Model to Predict Postoperative Improvement in Sub-Domains of the Modified Japanese Orthopedic Association Score for Degenerative Cervical Myelopathy
Assistant Professor of Neurosurgery and Orthopaedics Vanderbilt University Medical Center Nashville, Tennessee, United States
Introduction: Degenerative cervical myelopathy (DCM) is one of the most common disorders of the spinal cord. The modified Japanese Orthopedic Association (mJOA) score is a commonly used metric to quantify the severity of cervical myelopathy. Multiple studies have reported on predictors that influence improvement in the overall mJOA score; however, no study has assessed predictors of the mJOA sub-domains after elective surgical management for DCM. Our primary objective was to construct a clinical prediction model for improvement of mJOA sub-domains at 12-months following surgery for DCM.
Methods: We conducted a retrospective review of data collected from the Quality Outcomes Database (QOD). Patients were selected for inclusion if: 1) one of their predominant indications for cervical surgery was myelopathy or myelopathy was indicated as a spine-associated symptom, and 2) they completed one-year follow-up data. The outcomes of interest were the sub-domains or items of the mJOA at 12-months following surgery.
A multivariable proportional odds ordinal regression model was developed for patients with cervical myelopathy. The model included patient demographic, clinical, and surgery covariates, along with baseline sub-domain scores. The model was internally validated using bootstrap resampling to estimate the likely performance on a new sample of patients.
Results: The final patient sample included 5,000 patients. Patients had statistically significant improvement from baseline to 12-months post-surgery on all the mJOA sub-domains (p < 0.001). The model identified mJOA baseline sub-domains to be the strongest predictors of 12-month scores, with numbness in legs and ability to walk predicting 5 of the 6 mJOA items. Additional covariates predicting 3 or more items included age, preoperative anxiety/depression, gender, race, employment status, duration of symptoms, smoking status, and radiographic presence of listhesis. The discriminative ability of the model regarding joint probabilities measured by unweighted generalized C-index was 0.753.
Conclusion : For patients with DCM, our results highlight the importance of assessing preoperative numbness, walking ability, and the modifiable variables of anxiety/depression and smoking status. Additional factors to consider when counseling patients preoperatively are age, gender, race, employment status, duration of symptoms, and presence of listhesis. This model has the potential to assist surgeons, patients, and families when considering surgery for cervical myelopathy.
