There has been a generic dictum in spine and musculoskeletal clinical research that a minimum 2-year follow-up is necessary for patient-reported outcomes (PROs) to adequately assess the therapeutic effect of surgery; however, the rationale for this duration is not evidence based. The purpose of this study was to determine the follow-up time necessary to ensure that the effectiveness of a lumbar surgical intervention is adequately captured for three lumbar pathologies and three common PROs.
Using the different PROs of pain, physical function, and mental quality of life from the Canadian Spine Outcomes and Research Network (CSORN) prospective database, the authors assessed the time course to the recovery plateau following lumbar spine surgery for lumbar disc herniation, degenerative spondylolisthesis, and spinal stenosis. One-way ANOVA with post hoc testing was used to compare scores on the following standardized PRO measures at baseline and 3, 12, and 24 months postoperatively: Disability Scale (DS), visual analog scale (VAS) for leg and back pain, and SF-12 Mental Component Summary (MCS) and Physical Component Summary (PCS).
Significant differences for all spine pathologies and specific PROs were found with one-way ANOVA (p < 0.0001). The time to plateaued recovery after surgery for lumbar disc herniation (661 patients), lumbar stenosis (913 patients), and lumbar spondylolisthesis (563 patients) followed the same course for the following PRO measures: VAS for back and leg pain, 3 months; DS, 12 months; PCS, 12 months; and MCS, 3 months. Beyond these time points, no further significant improvements in PROs were seen. Patients with degenerative spondylolisthesis or spinal stenosis who had undergone fusion surgery plateaued at 12 months on the DS and PCS, compared to 3 months in those who had not undergone fusion.
Specific health dimensions follow distinctly different recovery plateaus, indicating that a 2-year postoperative follow-up is not required for all PROs to accurately assess the treatment effect of lumbar spinal surgery. Ultimately, the clinical research question should dictate the follow-up time and the outcome measure utilized; however, there is now evidence to guide the specific duration of follow-up for pain, physical function, and mental quality of life dimensions.