The Impact of Mental Health on Outcome after Anterior Cervical Discectomy: Assessing the Influence of Mental Health Using Predictive Modelling

Background: Depression and anxiety are common mental disorders among patients with chronic pain. It is hypothesized that patients suffering from one or both of these disorders benefit less from having surgery than patients who are mentally healthy. In this study we  assess and quantify the effect of mental status on the functional outcome after cervical spine surgery. Methods: 108 patients from the NECK trial, with radiculopathy due to a one level herniated disc, underwent anterior cervical discectomy and were included into this analysis. Functional outcome was quantified using the Neck Disability Index (NDI) and mental health status was measured using the Hospital Anxiety and Depression Score (HADS) questionnaire. Differences in NDI were assessed using Generalized Estimated Equations (GEE), crude mean values, a predictive Linear Mixed Model (LMM) using baseline scores and over time with an explanatory LMM. Results: At baseline, 24% and 32% of patients were respectively depressed and anxious, and had statistically significant and clinically relevant higher NDI scores during follow-up. However, in those patients in which the HADS returned to normal during follow up, NDI values decreased comparably to the non-depression or -anxiety cases. Those patients that demonstrated persisting high HADS values, had convincingly worse NDI scores. A predictive Linear Mixed Model (LMM) showed that combining baseline NDI and HADS scores was highly predictive of NDI during follow-up. The R-shiny application enabled the effective, visual communication of results from the predictive LMM. Conclusion: This study shows that mental health status and disability are strongly associated and provides insight into the size of the effect, as well as a way to use this relation to improve preoperative patient counselling. These findings give rise to the suggestion that incorporating mental health screening in the pre-operative assessment of patients could help to adequately manage patients’ expectations for functional recovery. Trial Registration: Dutch Trial Register Number: NTR1289 Funding: The NECK-trial was originally sponsored by Braun Medical (BBraun Medical paid €298.837 to cover the costs for research nurses) and when funding was retracted after the first analysis, the Department of Neurosurgery, Leiden University Medical Centre continued funding the trial. Declaration of Interest: CMWG [corresponding author], IB, FK, EWZ declare no competing interests. CVL: Grant: BBraun Medical (paid directly to institution). Speaking/Teaching Arrangements: CSRS, CSRS AP. Research Support (Investigator Salary, Staff/Materials): Medtronic, Paradigm, Covidien (paid directly to institution), Dutch National Organization (paid directly to institution). Fellowship Support: Chinese Student Council(student support/sponsorship). Royalties: EIT (amount not disclosed). MPA: Stock Ownership: Galapagos (amount not disclosed), Nuvasive (amount not disclosed). Consulting: Zimmer-Biomet (amount not disclosed, paid directly to institution), EIT (amount not disclosed, paid directly to institution), Silony (amount not disclosed, paid directly to institution), Intrinsics (amount not disclosed, paid directly to institution). Research Suppport: Zimmer- Biomet (amount not disclosed, paid directly to institution) EIT (amount not disclosed, paid directly to institution), Instrinsics (amount not disclosed, paid directly to institution). WCP: Grant: BBraun Medical (paid directly to institution), Hersenstichting Brain Foundation Netherlands (paid directly to institution), Center TBI (paid directly to institution). Ethical Approval: The NECK protocol was approved by the ‘Central Ethics Committee Leiden’(“Commissie Medische Ethiek LeidenUniversity Medical Center,” decision letter P08.011) and the ‘Medical Ethics Committee Noord-Holland’ (M08−038).