Influence of Preoperative Disability on Outcomes Following Primary Surgical Treatment of Cervical Disc Herniation.

Study design: Retrospective review.

Objective: To evaluate how preoperative disability influences patient-reported outcomes (PROs) following primary surgical intervention for cervical herniated disc.

Summary of background data: The effect of baseline disability has been evaluated for various spinal surgeries, but not specifically for primary cervical herniated disc.

Methods: A prospectively maintained single surgeon database was retrospectively reviewed to identify patients who underwent primary cervical spine surgery for herniated nucleus pulposus. Demographics, perioperative data, and baseline/postoperative PROs were collected including Neck Disability Index (NDI), Visual Analog Scale-Arm/Neck (VAS-A/N), 12-Item Short Form Mental/Physical Component Scores (SF-12 MCS/PCS), Patient-Reported Outcome Measure Information System-Physical Function (PROMIS-PF), and 9-Item Patient-Health Questionnaire (PHQ-9). Baseline NDI <50/≥50 defined 2 cohorts. ΔPROs were determined at 6-week postoperatively/final follow-up (average 11.8±7.7 postoperative months). Overall rates of minimal clinically important difference (MCID) achievement were determined for each PRO. Perioperative characteristics/demographics/baseline PROs were compared with χ2 tests (categorical variables)/the Student t test (continuous variables). Intercohort postoperative PROs/ΔPROs/MCID attainment rates were compared with multivariate linear regression (continuous variables)/multivariate logistic regression (categorical variables) accounting for differences in insurance type.

Results: Of 190 patients, there were 69 in the NDI ≥50 group. Patients with NDI ≥50 were more likely to have workers' compensation, or Medicare/Medicaid insurance (P<0.001) and report worse baseline PROs (P≤0.001, all). After controlling for insurance type, NDI ≥50 patients continued to report worse PROs at 6 weeks/final follow-up (P≤0.037, all), except PROMIS-PF at 6 weeks postoperatively. NDI ≥50 patients reported greater NDI improvements at 6 weeks (P=0.007) and final follow-up (P<0.001). NDI ≥50 patients experienced higher overall MCID achievement rates for PHQ-9/NDI (P≤0.015, both).

Conclusions: NDI ≥50 patients reported worse baseline mental/physical health and neck/arm pain and continued to report inferior postoperative outcomes including disability. Despite inferior absolute outcomes, NDI ≥50 patients reported greater improvements/achievement of clinically significant differences in disability through final follow-up. Further, these patients were more likely to experience clinically significant improvements in depressive burden.