Clinical Improvements in Myelopathy Result in Improved Patient-Reported Outcomes Following Anterior Cervical Discectomy and Fusion

Study Design. Retrospective cohort study. Objective. To determine if myelopathy severity predicted the magnitude of improvement in health-related quality of life metrics following anterior cervical discectomy and fusion (ACDF). Summary of Background Data. Surgery for myelopathy is primarily performed to halt disease progression. However, it is still controversial if these patients can expect significant health-related quality-of life improvements following ACDF. We explore the relationship between modified Japanese Orthopaedic Association (mJOA) improvements and its effect on other health-related quality-of life metrics. Materials and Methods. Patients undergoing ACDF for myelopathy were grouped based on preoperative mJOA scores into mild (15-17), moderate (12-14), and severe (<12) groups. Patients were subsequently categorized based on if they attained the minimum clinically detectable improvement (MCID) threshold for mJOA. Multivariate linear regression was performed to determine the magnitude of improvement in Δpatient-reported outcome measures. Results. A total of 374 patients were identified for inclusion. Of those, 169 (45.2%) had mild myelopathy, 125 (33.4%) had moderate, and 80 (21.4%) had severe myelopathy. Only the moderate and severe groups had significant improvements in mJOA following surgery (mild: P=0.073, moderate: P<0.001, severe: P<0.001). There were no significant differences in the magnitude of improvement for any patient-reported outcome measure based on myelopathy severity, except for mJOA (mild: 0.27, moderate: 1.88, severe: 3.91; P<0.001). Patients meeting the MCID for mJOA had better ΔShort-Form 12 Mental Component Score (3.29 vs. -0.21, P=0.007), ΔShort-Form 12 Physical Component Score (6.82 vs. 1.96, P<0.001), ΔVisual Analog Scale Neck (-3.11 vs. -2.17, P=0.001), ΔVisual Analog Scale Arm (-2.92 vs. -1.48, P<0.001), ΔNeck Disability Index (-18.35 vs. -7.86, P<0.001), and ΔmJOA (3.38 vs. -0.56, P<0.001) compared with patients who did not. Conclusions. Worse baseline myelopathy severity predicts worse postoperative outcomes. However, baseline myelopathy severity is not predictive of the magnitude of postoperative improvement with the exception of mJOA. Patients who attain MCID improvement in mJOA had greater postoperative improvement for other health-related quality of life metrics.