DOS 2020

202 · DOS Abstracts Patients operated for Spinal Stenosis with Degenerative Spondylolisthesis achieve a clinically meaningful effect, and the effect is sustained 5 years after surgery. Andreas Kiilerich Andresen, Christian Støttrup, Rune Paulsen, Peter Udby, Søren Fruensgaard, Leah Carreon Department of Spine Surgery, Spine Centre of Southern Denmark, Middelfart; Department of Orthopeadics, Kolding Hospital; Department of Orthopeadics, Køge Hospital; Spine Surgery, Silkeborg Regional Hospital Background: Lumbar Spinal Stenosis (LSS) with degenerative spondylolisthesis (DS) is a common condition in the elderly population which is associated with sig- nificant morbidity and decreased quality of life. For patients where pain and disability are unacceptable, surgical intervention with lumbar decompression is a commonly used treatment option, shown to provide relief of symptoms and pain. Few studies have examined if a clinically relevant difference in function is obtained, and whether this effect is sustained at long term. Purpose / Aim of Study: The aim of this study was to evaluate the patient re- ported outcomes, whether patients obtain a clinically relevant effect of surgery, and if the effect of treatment is sustained at one, two and five years postoperatively. Materials and Methods: The study was performed as a multicentre registry-based retrospective cohort study, in collaboration between Silkeborg, Køge and Middelfart hospital, using data collected prospectively in the Danish national surgical spine da- tabase; DaneSpine. All patients underwent decompression and un-instrumented fusion due to LSS with DS. This study evaluates both preoperative and postopera- tive outcomes. All PRO measures were filled out preoperatively and at 1, 2 and 5 years postoperatively. Based on the outcome measures, the patients who obtained a minimal clinically relevant difference in outcome (MCID) were identified at one, two- and five- years post-surgery. Outcome measures for the study included the Oswestry Disability Index (ODI), EuroQoL-5D-3L (EQ-5D), Visual Analogue Scale Leg Pain (VAS-leg) and Visual Analogue Scale Back Pain (VAS-back). Findings / Results: We found a mean change from surgery to 5 years of -18.9 on ODI; a mean change of 0.29 on EQ.5D, -29.2 on VAS leg and -21.3 on VAS back. We found that 83% of patients obtained a clinically relevant increase in one or more PROs. Apart from EQ-5D, there was no statistical difference in percentage of pa- tients who obtained MCID at one, two- and five-years post-surgery. Conclusions: Surgery for LSS with DS has favourable results, with many patients experiencing a clinically important change in outcome measures, and this change is maintained for at least 5 years. 181.