Wednesday, September 26, 2018 9:00 AM – 10:00 AM Best Papers Wednesday: 1. Effect of spinal decompression on back pain in lumbar spinal stenosis: canadian Spine Outcomes Research Network (CSORN) registry

BACKGROUND CONTEXT Lumbar spinal stenosis remains a common indication for lumbar spine surgery in older adults and accounts for an increasing number of surgical procedures in the past few decades. Surgical decompression is usually offered for improvement of neurogenic claudication in patients with lumbar canal stenosis. These patients often have associated Low Back Pain (LBP) and little is known about surgical results for this disabling symptom. PURPOSE The purpose of this study was to look at the effect of surgical intervention on back pain in patients with lumbar spinal stenosis. We wanted to quantify the improvement in LBP after surgical decompression and further investigate factors within this population that could have an effect on LBP symptoms. This would help us manage patient expectations and counsel them about effects of surgical intervention on their condition and symptoms. STUDY DESIGN/SETTING We conducted a multicenter, ambispective review of consecutive spine surgery patients enrolled by the Canadian Spine Outcomes and Research Network (CSORN) between 2012 and 2015. CSORN is a group of over 50 neurosurgical and orthopedic spine surgeons from tertiary care academic and non-academic hospitals across Canada that prospectively collected data on patients with spinal conditions. PATIENT SAMPLE Local research coordinators enrolled patients at each site. All patients with lumbar spinal stenosis who underwent surgical treatment were included in this study. Exclusion criteria were patients who had stenosis with instability. OUTCOME MEASURES Baseline preoperative patient characteristics included socio-demographic factors (age, sex, body mass index, nicotine use, education level, work status, marital status, others), medication and resource utilization, comorbidities, operative and postoperative variables including type of procedure, operating time, blood loss, and adverse events and length of hospital stay. Patient-Reported Outcome Measures (PROMS) used were Visual Analog Scale (VAS) for [back/leg pain] EuroQol EQ5D, SF-12 Physical (PCS) and Mental Component Summary (MCS), and Oswestry Disability Index (ODI). METHODS Consecutive patients who underwent surgical treatment for lumbar spinal stenosis without instability (1-2 level) were prospectively enrolled in the multicenter Canadian Spine Outcomes Research Network (CSORN) registry. Patient reported outcomes were collected at baseline and at 3, 12 and 24 months after surgery. Our primary outcomes were change in LBP (NRS) and disability (ODI). We considered a Minimal Clinically Important Difference (MCID) with change in NRS as 2 points and ODI as 10 points. The independent variables used in this study were measured on either categorical or continuous scales. The dependent variables (VAS pain scale and disability score) were categorized into minimal clinically important change (yes=1, no=0); thus, multivariable logistic regression was used to model the relationship between the outcomes and explanatory variables of interest using a backward conditional selection procedure. RESULTS A total of 1,340 patients were included in the analysis. Mean age was 65 years and 59% were males. Follow-up evaluations were available in 952 patients at 12 months and 548 patients at 24 months. LBP significantly improved 3 months after surgery and sustained at 24 months. We found that 74% of patients reached MCID with regard to NRS. Predictive factors for sustained improvement (12 and 24 months) in LBP after surgical intervention were absence of narcotic usage, severity of LBP prior to surgery (high NRS) and being a nonsmoker. Surgical factors such as type of surgical intervention, occurrence of intraoperative or postoperative adverse events, surgical time or length of stay had no predictive value in change in back pain scores. CONCLUSIONS LBP was statistically and clinically significantly alleviated at 3 months after lumbar decompression surgery for lumbar spinal stenosis and was maintained at 12 and 24 months after surgery in a vast majority of patients. Back pain severity, smoking status and narcotic usage were predictors in LBP improvement.