Is the Neck Disability Index an Appropriate Measure for Changes in Physical Function After Surgery for Cervical Spondylotic Myelopathy?

BACKGROUND: The Neck Disability Index (NDI) is a 10-item questionnaire about symptoms relevant to cervical spine pathology, originally validated in the physical therapy literature. It is unclear if all of the items apply to spine surgery. The purpose of this study was to determine if improvements in the composite NDI score or specific NDI domains are appropriate measures for tracking changes in physical function after surgical intervention for cervical spondylotic myelopathy (CSM). METHODS: A retrospective cohort review of patients treated at a major academic medical center was undertaken. Baseline and postoperative standardized outcome measurement scores, including composite NDI, NDI subdomain, and SF-12 physical component score (PCS), were collected. Wilcoxon signed-rank test was used to determine whether patients exhibited improvement in each of the outcome measures included. Multiple linear regression was performed to determine whether change in NDI composite or subdomain scores predicted change in physical function after surgery for CSM-compared with the well-validated PCS score-controlling for factors such as age, sex, etc. RESULTS: Baseline data were collected on 118 patients. All outcome measures exhibited significant improvement after surgery based on the Wilcoxon signed-rank test. On linear regression, work (ß = -2.419 [-3.831, -1.006]; P = .001) and recreation (ß = -1.354 [-2.640, -0.068]; P = .039), as well as the NDI composite score (ß = -0.223 [-0.319, -0.127]; P < .001), were significant predictors of change in physical function over time. CONCLUSIONS: Although the NDI composite score did predict change in PCS over time, only 2 of the 10 NDI subdomains were found to be associated with change in physical function over time. Based on these results, the item bank and composite scoring of the NDI are inappropriate for evaluating quality of life in studies of surgically treated cervical spondylotic myelopathy patients. CLINICAL RELEVANCE: NDI may not be a valid tool in the determination of physical function changes after surgery for CSM. LEVEL OF EVIDENCE: III.

Utilization of Time-driven Activity-based Costing to Determine the True Cost of a Single or 2-level Anterior Cervical Discectomy and Fusion.

STUDY DESIGN: This is a prospective case series. OBJECTIVE: To determine the actual cost of performing 1- or 2-level anterior cervical discectomy and fusion (ACDF) using actual patient data and the time-driven activity-based cost methodology. SUMMARY OF BACKGROUND DATA: As health care shifts to use value-based reimbursement, it is imperative to determine the true cost of surgical procedures. Time-driven activity-based costing determines the cost of care by determining the actual resources used in each step of the care cycle. MATERIALS AND METHODS: In total, 30 patients who underwent a 1- or 2-level ACDF by 3 surgeons at a specialty hospital were prospectively enrolled. To build an accurate process map, a research assistant accompanied the patient to every step in the care cycle including the preoperative visit, the preadmission testing, the surgery, and the postoperative visits for the first 90 days. All resources utilized and the time spent with every member of the care team was recorded. RESULTS: In total, 27 patients were analyzed. Eleven patients underwent a single-level ACDF and 16 underwent a 2-level fusion. The total cost for the episode of care was $29,299±$5048. The overwhelming cost driver was the hospital disposable costs ($13,920±$6325) which includes every item used during the hospital stay. Intraoperative personnel costs including fees for the surgeon, resident/fellow, anesthesia, nursing, surgical technician, neuromonitoring, radiology technician and orderlies, accounted for the second largest cost at $6066±$1540. The total cost excluding hospital overhead and disposables was $9071±$1939. CONCLUSIONS: Reimbursement for a bundle of care surrounding a 1- or 2-level ACDF should be no less than $29,299 to cover the true costs of the care for the entire care cycle. However, this cost may not include the true cost of all capital expenditures, and therefore may underestimate the cost.

Which Domains of the ODI Best Predict Change in Physical Function in Patients After Surgery for Degenerative Lumbar Spondylolisthesis?

STUDY DESIGN: A retrospective review. OBJECTIVE: The purpose of this study is to determine the differential improvement of the various individual items of the Oswestry Disability Index (ODI) and to determine their relationship to other measures of Health Related Quality of Life (HRQOL). SUMMARY OF BACKGROUND DATA: The ODI is an easily scored, common, 10-item questionnaire about symptoms relevant to lumbar spine pathology. It is not clear if all of the items can be reliably applied to spine surgery. The purpose of this study is to determine the differential improvement of the various individual items of the ODI and to determine their relationship to other measures of HRQOL. METHODS: Analysis of a prospective registry of patients treated at an academic medical center was undertaken. At baseline, standardized outcome measures including ODI and SF12 PCS were collected on all patients undergoing elective fusion surgery for degenerative spondylolisthesis. Multiple linear regressions were performed using change in SF12 PCS as the dependent variable and change in ODI components as the independent variables. RESULTS: Baseline and 1-year follow-up data were collected on 196 patients (mean age 60.4 years). There were statistically significant differences in improvement among ODI items. Surprisingly, the most improvement after surgery was noted in the standing, sex life, and social life domains. The least improvement was noted in the personal care, sleeping, and sitting domains. Linear regression for change in ODI components versus change in SF-12 PCS revealed a significant correlation (R = 0.353, P ≤ 0.001). The only retained domains in the final model were change in lifting, standing, and traveling as predictors for ΔPCS. CONCLUSION: All domains of the ODI do not improve equally after surgery for degenerative spondylolisthesis. Some of the domains that improve most (e.g., sex life) have no discernible relationship to the known pathophysiology of degenerative spondylolisthesis. Based upon these results, we conclude that the item bank and composite scoring of the ODI are inappropriate for evaluating quality of life in studies of surgically treated degenerative spondylolisthesis patients. LEVEL OF EVIDENCE: 3.

Is It Necessary to Extend a Multilevel Posterior Cervical Decompression and Fusion to the Upper Thoracic Spine?

STUDY DESIGN: A retrospective cohort analysis. OBJECTIVE: The aim of this study was to determine if there is a difference in the revision rate in patients who undergo a multilevel posterior cervical fusions ending at C7, T1, or T2-T4. SUMMARY OF BACKGROUND DATA: Multilevel posterior cervical decompression and fusion is a common procedure for patients with cervical spondylotic myelopathy, but there is little literature available to help guide the surgeon in choosing the caudal level of a multilevel posterior cervical fusion. METHODS: Patients who underwent a three or more level posterior cervical fusion with at least 1 year of clinical follow-up were identified. Patients were separated into three groups on the basis of the caudal level of the fusion, C7, T1, or T2-T4, and the revision rate was determined. In addition, the C2-C7 lordosis and the C2-C7 sagittal vertical axis (SVA) was recorded for patients with adequate radiographic follow-up at 1 year. RESULTS: The overall revision rate was 27.8% (61/219 patients); a significant difference in the revision rates was identified between fusions terminating at C7, T1, and T2-T4 (35.3%, 18.3%, and 40.0%, P = 0.008). When additional variables were taken into account utilizing multivariate linear regression modeling, patients whose construct terminated at C7 were 2.29 (1.16-4.61) times more likely to require a revision than patients whose construct terminated at T1 (P = 0.02), but no difference between stopping at T1 and T2-T4 was identified. CONCLUSION: Multilevel posterior cervical fusions should be extended to T1, as stopping a long construct at C7 increases the rate of revision. LEVEL OF EVIDENCE: 3.