Depressive Symptoms and Hypothalamic-Pituitary-Adrenal Axis (HPA) Function as Predictors for Clinical Outcome after Lumbar Spine Stabilization and Fusion Surgery

Background: Low back pain (LBP) is one of the most frequent diseases and has a prevalence of 90%. Degenerative disc disease (DDD) is a common reason for LBP. Surgical treatment of DDD includes lumbar interbody fusion which fails in up to 32% in even well-diagnosed patients. The literature regarding the benefit of psychological screening before lumbar surgery showed that psychological factors are important comorbidities especially in patients with poor outcome. But as depression is often a comorbidity already before surgery, use as an outcome predictor is not very reliable.

Depression is considered to be a stress disorder and abnormalities in the hypothalamic-pituitary-adrenal axis (HPA), which is activated in response to psychological stress, have been demonstrated. In this study we combine psychological screening with hormone diagnostics to increase the value as an outcome predictor in spine surgery.

Methods: In this prospective, ongoing study, 100 patients undergoing single segment lumbar fusion for DDD receive psychiatric screening tests regarding depressive symptoms and blood examinations regarding function of the HPA. Clinical outcome is measured by Spine Tango Registry and Core Outcome Measures Index at 6 and 12 weeks follow-up to rate outcome from the patients and the surgeons’ perspective. Outcome data are being correlated with depressive symptoms and function of the HPA to prove their value as outcome predictors.

Results: There are preliminary results of this ongoing study with 25 patients included so far. Single segment lumbar stabilization and fusion is an effective and safe surgical therapy for treatment of degenerative spinal disease. Furthermore preliminary results suggest that postoperative good clinical outcome correlates with improvement in BDI and HAM-D scores. Correlation of high BDI, HAM-D scores, and cortisol plasma level, as described in literature, could not be proven by our study so far.

Conclusion: Preliminary results suggest that psychological screening and hormone blood tests can prevent poor outcome in single patients. Correlation of BMI, HAM-D scores, and clinical outcome seems not to be like previous studies suggested but instead showing an inverse correlation.