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Objective: To assess whether decompression alone is non-inferior to decompression with instrumented fusion five years after primary surgery in patients with degenerative lumbar spondylolisthesis., Design: Five year follow-up of a randomised, multicentre, non-inferiority trial (Nordsten-DS)., Setting: 16 public orthopaedic and neurosurgical clinics in Norway., Participants: Patients aged 18-80 years with symptomatic lumbar spinal stenosis and a spondylolisthesis of 3 mm or more at the stenotic level., Interventions: Decompression surgery alone and decompression with additional instrumented fusion (1:1)., Main Outcome Measures: The primary outcome was a 30% or more reduction in Oswestry disability index from baseline to five year follow-up. The predefined non-inferiority margin was a -15 percentage point difference in the proportion of patients who met the primary outcome. Secondary outcomes included the mean change in Oswestry disability index, Zurich claudication questionnaire, numeric rating scale for leg and back pain, and EuroQol Group 5-Dimension (EQ-5D-3L) questionnaire., Results: From 12 February 2014 to 18 December 2017, 267 participants were randomly assigned to decompression alone (n=134) and decompression with instrumented fusion (n=133). Of these, 230 (88%) responded to the five year questionnaire: 121 in the decompression group and 109 in the fusion group. Mean age at baseline was 66.2 years (SD 7.6), and 69% were women. In the modified intention-to-treat analysis with multiple imputation of missing data, 84 (63%) of 133 people in the decompression alone group and 81 (63%) of 129 people in the fusion group had a at least a 30% reduction in Oswestry disability index, a difference of 0.4 percentage points. (95% confidence interval (CI) -11.2 to 11.9). The respective results of the per protocol analysis were 65 (65%) of 100 in the decompression alone group and 59 (66%) of 89 in the fusion group, a difference of -1.3 percentage points (95% CI -14.5 to 12.2). Both 95% CIs were higher than the predefined non-inferiority margin of -15%. The mean change in Oswestry disability index from baseline to five years was -17.8 in both groups (mean difference 0.02 (95% CI -3.8 to 3.9)). Results of the other secondary outcomes were in the same direction as the primary outcome. From two to five year follow-up, a new lumbar operation occurred in six (5%) of 123 people in the decompression group and 11 (10%) of 113 people in the fusion group, with a total from baseline to five years of 21 (16%) of 129 people and 23 (18%) of 125, respectively., Conclusions: In participants with degenerative spondylolisthesis, decompression alone was non-inferior to decompression with instrumented fusion five years after primary surgery. Proportions of subsequent surgeries at the index level or an adjacent lumbar level were no different between the groups., Trial Registration: ClinicalTrials.gov NCT02051374., Competing Interests: Competing interests: All authors have completed the ICMJE uniform disclosure form www.icmje.org/disclosure-of-interest/ and declared that they have had no financial relationships with any organisation that may have a financial interest in the submitted work in the previous three years and no relationships or activities that could have influenced the submitted work., (© Author(s) (or their employer(s)) 2019. Re-use permitted under CC BY-NC. No commercial re-use. See rights and permissions. Published by BMJ.)

Background Context: Patients with spinal stenosis and degenerative spondylolisthesis are treated surgically with decompression alone or decompression with fusion. However, there is debate regarding which subgroups of patients may benefit from additional fusion., Purpose: To investigate possible treatment effect modifiers and prognostic variables among patients operated for spinal stenosis and degenerative spondylolisthesis., Design: A secondary exploratory study using data from the Norwegian Degenerative Spondylolisthesis and Spinal Stenosis (NORDSTEN-DS) trial. Patients were randomized to decompression alone or decompression with instrumented fusion., Patient Sample: The sample in this study consists of 267 patients from a randomized multicenter trial involving 16 hospitals in Norway. Patients were enrolled from February 12, 2014, to December 18, 2017. The study did not include patients with degenerative scoliosis, severe foraminal stenosis, multilevel spondylolisthesis, or previous surgery., Outcome Measures: The primary outcome was an improvement of ≥ 30% on the Oswestry Disability Index score (ODI) from baseline to 2-year follow-up., Methods: When investigating possible variables that could modify the treatment effect, we analyzed the treatment arms separately. When testing for prognostic factors we analyzed the whole cohort (both treatment groups). We used univariate and multiple regression analyses. The selection of variables was done a priori, according to the published trial protocol., Results: Of the 267 patients included in the trial (183 female [67%]; mean [SD] age, 66 [7.6] years), complete baseline data for the variables required for the present analysis were available for 205 of the 267 individuals. We did not find any clinical or radiological variables at baseline that modified the treatment effect. Thus, none of the commonly used criteria for selecting patients for fusion surgery influenced the chosen primary outcome in the two treatment arms. For the whole cohort, less comorbidity (American Society of Anesthesiologists Classification [ASA], OR = 4.35; 95% confidence interval (CI [1.16-16.67]) and more preoperative leg pain (OR = 1.23; CI [1.02-1.50]) were significantly associated with an improved primary outcome., Conclusions: In this study on patients with degenerative spondylolisthesis, neither previously defined instability criteria nor other pre-specified baseline variables were associated with better clinical outcome if fusion surgery was performed. None of the analyzed variables can be applied to guide the decision for fusion surgery in patients with degenerative spondylolisthesis. For both treatment groups, less comorbidity and more leg pain were associated with improved outcome 2 years after surgery., Trial Registration: NORDSTEN-DS ClinicalTrials.gov, NCT02051374., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2023 The Author(s). Published by Elsevier Inc. All rights reserved.)

Background: In patients with lumbar spinal stenosis and degenerative spondylolisthesis, it is uncertain whether decompression surgery alone is noninferior to decompression with instrumented fusion., Methods: We conducted an open-label, multicenter, noninferiority trial involving patients with symptomatic lumbar stenosis that had not responded to conservative management and who had single-level spondylolisthesis of 3 mm or more. Patients were randomly assigned in a 1:1 ratio to undergo decompression surgery (decompression-alone group) or decompression surgery with instrumented fusion (fusion group). The primary outcome was a reduction of at least 30% in the score on the Oswestry Disability Index (ODI; range, 0 to 100, with higher scores indicating more impairment) during the 2 years after surgery, with a noninferiority margin of -15 percentage points. Secondary outcomes included the mean change in the ODI score as well as scores on the Zurich Claudication Questionnaire, leg and back pain, the duration of surgery and length of hospital stay, and reoperation within 2 years., Results: The mean age of patients was approximately 66 years. Approximately 75% of the patients had leg pain for more than a year, and more than 80% had back pain for more than a year. The mean change from baseline to 2 years in the ODI score was -20.6 in the decompression-alone group and -21.3 in the fusion group (mean difference, 0.7; 95% confidence interval [CI], -2.8 to 4.3). In the modified intention-to-treat analysis, 95 of 133 patients (71.4%) in the decompression-alone group and 94 of 129 patients (72.9%) in the fusion group had a reduction of at least 30% in the ODI score (difference, -1.4 percentage points; 95% CI, -12.2 to 9.4), showing the noninferiority of decompression alone. In the per-protocol analysis, 80 of 106 patients (75.5%) and 83 of 110 patients (75.5%), respectively, had a reduction of at least 30% in the ODI score (difference, 0.0 percentage points; 95% CI, -11.4 to 11.4), showing noninferiority. The results for the secondary outcomes were generally in the same direction as those for the primary outcome. Successful fusion was achieved with certainty in 86 of 100 patients (86.0%) who had imaging available at 2 years. Reoperation was performed in 15 of 120 patients (12.5%) in the decompression-alone group and in 11 of 121 patients (9.1%) in the fusion group., Conclusions: In this trial involving patients who underwent surgery for degenerative lumbar spondylolisthesis, most of whom had symptoms for more than a year, decompression alone was noninferior to decompression with instrumented fusion over a period of 2 years. Reoperation occurred somewhat more often in the decompression-alone group than in the fusion group. (NORDSTEN-DS ClinicalTrials.gov number, NCT02051374.)., (Copyright © 2021 Massachusetts Medical Society.)