Lumbar fusion surgery in the era of an aging society: analysis of a nationwide population cohort with minimum 8-year follow-up

Fusions for lumbar spine diseases are widely performed and have a growing incidence, especially in elderly population. The goal of this study was to assess national trends of lumbar spinal fusions and examine the risk for reoperations after a lumbar fusion with a focus on ‘epidemiologic transition’ relating to age. The prospectively collected Korean Health Insurance Review and Assessment Service (HIRA) nationwide cohort database was retrospectively reviewed. The total 278,815 patients who underwent lumbar spinal fusions for degenerative spine diseases between 2010 and 2018 were reviewed and used to assess trends in operative incidence. The 37,050 patients who underwent lumbar fusions between 1/2010 and 12/2011 were enrolled to determine 8-year reoperation rates. The overall number of lumbar spinal fusions were analyzed for the national annual trend. Demographic data, reoperation rates, and confounding clinical factors were evaluated. The overall number of lumbar spinal fusions was analyzed to determine the national annual trend of operative incidence. For the reoperation rate analysis, the primary outcome measured was the cumulative incidence of revision operations within a minimum 8-year follow-up period. Additional outcomes included comparative analyses of the reoperation rate with respect to age, sex, or other underlying comorbidities. Over time, elderly patients comprised a larger portion of the cohort (2010:24.2%; 2018:37.6%), while operations in younger patients decreased over time (2010:40.3%; 2018:27.0%). In the cohort of patients with a minimum 8-year follow-up (n=37,050), rates of reoperation peaked in patients aged 60–69 years (17.6 per 1000 person-years [HR 2.20 compared to