Neck Disability at Presentation Influences Long-Term Clinical Improvement for Neck Pain, Arm Pain, Disability, and Physical Function in Patients Undergoing Anterior Cervical Discectomy and Fusion.

OBJECTIVE: To compare perioperative characteristics, patient-reported outcome measures (PROMs) and minimum clinically important difference (MCID) achievement after anterior cervical discectomy and fusion (ACDF) in patients stratified by preoperative neck disability. BACKGROUND: The Neck Disability Index (NDI) assesses a patient's self-perceived neck disability and is often used to assess the efficacy of cervical surgical intervention. Our study (a retrospective cohort study) evaluates how preoperative severity of patient neck disability influences postoperative clinical improvement after ACDF. METHODS: Primary, single-level, or multilevel ACDF procedures were included. PROMs were administered at preoperative/6 week/12 week/6 month/1 year/2 year time points and included Patient-Reported Outcome Measurement Information System-Physical Function (PROMIS-PF), visual analog scale (VAS) for neck and arm pain, NDI, and 12-Item Short-Form (SF-12) Physical Composite Score (PCS). Patients were grouped according to preoperative NDI <50 (mild to moderate neck disability) or NDI >= 50 (severe neck disability). Demographics/perioperative characteristics/postoperative complications/mean PROMs/MCID achievement rates were compared using chi(2) or Student t test. Postoperative improvement from preoperative baseline within each cohort was assessed with paired-samples t test. MCID achievement was determined by comparing APROMs with established thresholds. RESULTS: A total of 225 patients were included, 150 NDI <50 and 75 NDI >= 50. The NDI >= 50 cohort was significantly younger (P = 0.002). Cohorts did not differ for spinal disease/operative duration/estimated blood loss/postoperative length of stay/postoperative narcotic consumption/adjacent segment disease rate/1-year arthrodesis rate/6-month pseudarthrosis rate. Postoperative VAS pain score on postoperative day 0 and 1 was significantly increased in the NDI >= 50 cohort (P < 0.048, all). Postoperative complication rates did not differ. All mean PROMs differed at all time points (P < 0.043, all). The NDI <50 patient cohort significantly improved from preoperative baseline for all PROMs and time points except SF-12 PCS/Patient-Reported Outcome Measurement Information System-Physical Function at 6 weeks. The NDI >= 50 cohort significantly improved for all PROMs and time points except SF-12 PCS at 6 weeks. The NDI >= 50 cohort showed a greater proportion achieving MCID for NDI at 6 weeks/2 years/overall (P < 0.037, all). CONCLUSIONS: Both cohorts showed significant long-term clinical improvement for neck pain/arm pain/physical function/neck disability, although patients with severe preoperative neck disability reported inferior mean scores for these outcomes at all time points.