Does Preoperative Degenerative Spondylolisthesis Influence Outcome in Degenerative Lumbar Spinal Stenosis? Three-Year Results of a Swiss Prospective Multicenter Cohort Study.

BACKGROUND Decompression alone to treat degenerative lumbar stenosis with and without concomitant degenerative spondylolisthesis (DS; non-DS) has shown ambiguous results in the literature. OBJECTIVE The aim is to compare clinical outcomes in DS and non-DS patients with lumbar stenosis who underwent decompression alone surgery without fusion on 1-3 adjacent levels after 6-month, 12-month, 24-month, and 36-month follow-up. METHODS We conducted a prospective cohort study at 8 medical centers. The main outcomes of this study are changes in Spinal Stenosis Measure (SSM) symptoms score, SSM function score, and quality of life (EQ-5D-3L sum score) over time. Propensity score matching for DS versus non-DS was applied. RESULTS One hundred seventy-seven patients met the inclusion criteria, 68 of whom had DS. In the matched cohort (n = 136), the estimated difference in SSM symptoms score of DS versus non-DS for changes from baseline to 36 months was 0.21 (95% CI, -0.15 to 0.57). For SSM function score, the estimated difference from baseline to 36 months was 0.05 (-0.21 to 0.31). Differences in changes between groups in EQ-5D-3L sum score were estimated to be -3.66 (-10.63 to 3.31) from baseline to 36 months. None of the group differences between the non-DS and the DS group was statistically significant. All matched patients improved over time in all additional outcomes. CONCLUSIONS Even after 3 years of follow-up, we show that among patients with degenerative lumbar spinal stenosis, both groups (DS and non-DS) distinctively take advantage of decompression alone without fusion