Regional Variance in Disability and Quality-of-Life Outcomes After Surgery for Grade I Degenerative Lumbar Spondylolisthesis: A Quality Outcomes Database Analysis

Objective

Regional differences in outcomes after spine surgery are poorly understood. We assessed disability and quality-of-life outcomes by geographic region in the United States using the NeuroPoint Alliance Quality Outcomes Database.

Methods

We queried the prospective Quality Outcomes Database patient registry to identify patients who underwent elective 1- or 2-level lumbar surgery for grade I degenerative spondylolisthesis from July 2014 through June 2016. Primary outcome measures included Oswestry Disability Index (ODI) and EuroQOL-5D (EQ-5D) reported at 24 months postoperatively. Differences in EQ-5D and ODI were compared across geographic regions of the United States (Northeast, Midwest, South, West).

Results

We identified 608 patients from 12 centers who underwent surgery. Of these, 517 (85.0%) had ODI data and 492 (80.9%) had EQ-5D data at 24 months. Southern states had the largest representation (304 patients; 5 centers), followed by Northeastern (114 patients; 3 centers), Midwestern (96 patients; 2 centers), and Western (94 patients; 2 centers) states. Baseline ODI scores were significantly different among regions, with the South having the greatest baseline disability burden (Northeast: 40.9 ± 16.9, South: 51.2 ± 15.8, Midwest: 40.9 ± 17.8, West: 45.0 ± 17.1, P < 0.001). The change in ODI at 24 months postoperatively was significantly different among regions, with the South showing the greatest ODI improvement (Northeast: −21.1 ± 18.2, South: −26.5 ± 20.2, Midwest: −18.2 ± 22.9, West: −21.7 ± 19.6, P < 0.001). All regions had ≥60% achievement of the minimum clinically important difference in ODI at 24 months postoperatively. No regional differences were observed for EQ-5D.

Conclusion

Significant regional variation exists for disability outcomes, but not quality of life, at 24 months after spinal surgery for grade I degenerative spondylolisthesis.

Introduction

Lumbar degenerative disease is a pervasive cause of disability and pain, with lumbar stenosis affecting more than 200,000 adults in the United States (US)¹ and lumbar spondylolisthesis affecting 11.5% of the US population.² Surgical interventions including decompressive laminectomy with or without instrumentation and fusion may be indicated in patients who have failed conservative medical management of symptomatic lumbar spondylolisthesis.^3,4 Importantly, the Spine Patient Outcomes Research Trial demonstrated that surgery for degenerative lumbar disease improved health and decreased cost per quality-adjusted life year compared with medical management alone.⁵ After recent health policy reforms, increased emphasis has been placed on value-based medical care, including patient outcomes after surgery for degenerative lumbar disease.⁶

Regional variations in lumbar spinal surgery techniques/rates,7, 8, 9 costs,^10,11 pain control regimens,¹² and patient outcomes¹⁰ have been studied previously. Prior studies have also investigated quality-of-life differences between international cohorts ^13,14; however, to our knowledge, no study has specifically investigated regional differences in patient disability or quality of life at long-term follow-up. As multi-institutional patient registries and multicenter studies have become more commonplace, regional differences in outcome measures reported in such studies are potentially under-reported and may affect how results from such studies are interpreted.

The Neuropoint Alliance Quality Outcomes Database (QOD) is a prospective, longitudinal, multicenter patient registry developed specifically to study patient outcomes after neurosurgical intervention.¹⁵ Since the formation of the Neuropoint alliance in 2008, the QOD has collected perioperative data as well as postoperative follow-up information at each participating site. Institutions from across the US are represented in the QOD data set, with a total of 12 participating high-volume sites with representation from each of the 4 mainland US Census Bureau geographic regions (Northeast, South, Midwest, West).

The objective of this study was to analyze regional variation in disability and quality-of-life outcomes after 1- or 2-level decompression and/or fusion for grade 1 spondylolisthesis using the multi-institutional QOD.