Preoperative Neck Disability Severity Limits Extent of Postoperative Improvement Following Cervical Spine Procedures

OBJECTIVE: Our study aims to evaluate the impact of severity of preoperative Neck Disability Index (NDI) on postoperative patient-reported outcome measures (PROMs). METHODS: A retrospective review of primary, elective, single or multilevel anterior cervical discectomy and fusion or cervical disc arthroplasty procedures between 2013 and 2019 was performed. Visual analogue scale (VAS) neck and arm, NDI, 12-item Short Form physical and mental composite score (SF-12 PCS and MCS), Patient-Reported Outcome Measurement Information System physical function, and 9-item Patient Health Questionnaire (PHQ-9) were collected preoperatively and postoperatively. Patients were categorized by preoperative NDI: none-to-mild disability (< 30); moderate disability (≥ 30 to < 50); severe disability (≥ 50 to < 70); complete disability (≥ 70). The impact of preoperative NDI on PROM scores and minimum clinically important difference (MCID) achievement rates were evaluated. RESULTS: The cohort included 74 patients with none-to-mild disability, 95 moderate, 76 severe, and 17 with complete disability. Patients with greater preoperative disability demonstrated significantly different scores for NDI, VAS neck, SF-12 MCS, and PHQ-9 at all timepoints (p < 0.001). Patients with more severe disability demonstrated different magnitudes of improvement for NDI (all p < 0.001), VAS neck (p ≤ 0.009), VAS arm (p = 0.025), and PHQ-9 (p ≤ 0.011). The effect of preoperative severity on MCID achievement was demonstrated for NDI and for PHQ-9 (p ≤ 0.007). CONCLUSION: Patients with severe neck disability demonstrated differences in pain, disability, physical and mental health. MCID achievement also differed by preoperative symptoms severity. Patients with more severe neck disability may be limited to the degree of improvement in quality of life but perceive them as significant changes.