Friday, September 28, 2018 10:30 AM–12:00 PM abstracts: complications of cervical spine surgery: 157. Risk factors associated with failure to reach minimum clinically important difference in patient-reported outcomes after anterior cervical discectomy and fusion

Abstract

BACKGROUND CONTEXT The minimum clinically importance difference (MCID) represents a threshold for improvements in patient-reported outcomes (PROs) that patients deem important following spine surgery. However, no study has comprehensively examined potential risk factors for failure to achieve MCID after anterior cervical discectomy and fusion procedures. PURPOSE To determine risk factors for failure to reach MCID for Neck Disability Index (NDI), Visual Analogue Scale (VAS) neck pain, and VAS arm pain in patients undergoing one- or two-level ACDF procedures. STUDY DESIGN/SETTING Retrospective analysis of a prospectively maintained surgical database. PATIENT SAMPLE A total of 229 patients who underwent primary, one- or two-level ACDF from 2005 to 2016. OUTCOME MEASURES NDI, CCI, ASA, VAS neck and VAS arm pain. METHODS Rates of overall MCID achievement for NDI, VAS neck pain, and VAS arm pain at final clinical follow up were calculated based on published MCID values. Bivariate testing via Poisson regression with robust error variance was used to test for association of demographic and procedural characteristics with failure to reach MCID for each PRO. The final multivariate model including all demographic and procedural categories as controls was created using backward, stepwise regression until only those variables with p RESULTS After exclusion of patients with incomplete PRO survey data, 78, 78, and 73 patients were included in the analysis for VAS neck, VAS arm, and NDI, respectively. Rates of MCID achievement for VAS neck, VAS arm, and NDI were 52.56%, 35.90%, and 73.97%, respectively. Upon bivariate analysis, patients with Charlson Comorbidity Index (CCI)≥2 were less likely to achieve MCID for NDI than patients with CCI 2 (RR 0.69, p=.017) were associated with failure to reach MCID for NDI. CONCLUSIONS The results of this study suggest that the majority of patients do not reach MCID for arm pain. Additionally, higher comorbidity burden as evidenced by higher CCI and ASA scores may be negative predictive factors for the achievement of MCID in neck disability following ACDF.