Survivorship analysis of laminectomy with or without fusion for spinal stenosis or degenerative spondylolisthesis: a national retrospective cohort study.

Lumbar spinal stenosis and spondylolisthesis are common degenerative problems. The benefits of decompressive laminectomy are proven, however, there is debate on whether laminectomy plus fusion offers significant clinical benefit. Long term follow-up in prospective trials is challenging for this population and therefore there is little evidence on longer term mortality following surgery. Mortality is an important outcome whereas improved mobility has been shown to improve overall survival in other surgical realms. The objective of this study was to explore a comparative survival analysis analyzing survival of patients undergoing laminectomy with or without fusion for lumbar spinal stenosis or spondylolisthesis, and to consider the association between patient factors and surgical procedure. We also investigated whether it is possible to evaluate differences in survival based on diagnosis. This was a population level retrospective cohort study. This study evaluated 56, 520 patients undergoing inpatient surgery for degenerative conditions of the lumbar spine from the Canadian Research Data Centre Network's Atlantic Research Data Centre holdings (the exposure included either laminectomy with or without fusion. Statistics Canada was uniquely linked with the Discharge Abstract Database to establish survivorship to assess 5 and 10 year survival rates (i.e. Mortality). Kaplan-Meier analyses were performed to establish survivorship curves, with survivorship defined as freedom from all-cause mortality. Databases did not control for frailty or comorbidity through Charlson Co-morbidity Index adjustment. Patients with spondylolisthesis had a small survivorship advantage at 5- and 10-years post operation (94.8%, 83.8%) compared to those with spinal stenosis (91.2%, 76.5%). However, for both spinal stenosis and spondylolisthesis, there was no difference in survival regardless of surgical treatment once controlling for age, sex and rural living. Younger age was associated with increased rates of fusion both within and between groups (p < 0.001). For patients with spinal stenosis, female sex and rural status were associated with increased survival regardless of surgical procedure (p < 0.001). This study found no difference in survival for patients undergoing laminectomy with or without fusion for lumbar spinal stenosis and degenerative spondylolisthesis although these results should be interpreted with caution. Unmeasured comorbidity due to data availability should be considered in the interpretation. Thus, the clinical benefit of the addition of fusion to laminectomy for degenerative lumbar spine conditions remains unclear and warrants further investigation with appropriate consideration of confounding known to affect mortality.