Predictors of Delayed Clinical Benefit Following Surgical Treatment for Low Grade Spondylolisthesis.

Abstract

Retrospective review of prospectively collected data. To investigate what factors predict delayed improvement after surgical treatment of low grade spondylolisthesis. Lumbar surgery leads to clinical improvement in the majority of patients with low grade spondylolisthesis. Most patients improve rapidly after surgery, but some patients demonstrate a delayed clinical course. The Quality and Outcomes Database (QOD) was queried for grade 1 spondylolisthesis patients who underwent surgery who had patient reported outcome measures (PROMs) collected at baseline, 3-, 6- and 12-months, including back and leg pain numeric rating scale (NRS), Oswestry Disability Index (ODI), and EuroQol-5D (EQ-5D). Patients were stratified as "Early responders" reaching MCID at 3 months and maintaining improvement through 12 months and "Delayed responders" not reaching MCID at 3 months but ultimately reaching MCID at 12 months. These two groups were compared with respect to factors which predicted delayed improvement. Of 608 patients enrolled, 436 (72%) met inclusion criteria for this study. Overall, 317 patients (72.7%) reached MCID for ODI at 12 months following surgery. Of these patients, 249 (78.5%) exhibited a rapid clinical improvement trajectory and had achieved ODI MCID threshold by the 3-month postop follow-up. 68 patients (21.4%) showed a delayed trajectory, and had not achieved ODI MCID threshold at 3 months, but did ultimately reach MCID at 12-month follow-up. Factors associated with delayed improvement included impaired preoperative ambulatory status, better baseline back and leg pain scores, and worse 3-month leg pain scores (P<0.01). The majority of patients undergoing surgery for low grade spondylolisthesis reach ODI MCID threshold rapidly, within the first three months after surgery. Factors associated with a delayed clinical course include impaired preoperative ambulation status, relatively better preoperative back and leg pain, and persistent leg pain at 3 months.