Operative vs Nonoperative Treatment for Adult Symptomatic Lumbar Scoliosis at 8-Year Follow-Up: A Nonrandomized Clinical Trial

Importance: Long-term follow-up studies of operative and nonoperative treatment of adult symptomatic lumbar scoliosis (ASLS) are needed to assess benefits and durability. Objective: To assess the durability of treatment outcomes for operative vs nonoperative treatment of ASLS. Design, Setting, and Participants: The Adult Symptomatic Lumbar Scoliosis 1 (ASLS-1) study was a multicenter, prospective study with randomized and observational cohorts designed to assess operative vs nonoperative ASLS treatment. Operative and nonoperative patients were compared using as-treated analysis of combined randomized and observational cohorts. Patients with ASLS aged 40 to 80 years were enrolled at 9 centers in North America. Data were analyzed from November 2023 to July 2024. Interventions: Operative and nonoperative treatment approaches. Main Outcomes and Measures: Primary outcomes measures were the Oswestry Disability Index (ODI) and Scoliosis Research Society 22 (SRS-22) at 2-, 5-, and 8-year follow-up. Results: The 286 enrolled patients (104 in the nonoperative group: median [IQR] age, 61.9 [54.4-68.8] years; 97 female [93%]; 182 in the operative group: median [IQR] age, 60.2 [53.5-66.6] years; 161 female [88%]) had follow-up rates at 2, 5, and 8 years of 90% (256 of 286), 70% (199 of 286), and 72% (205 of 286), respectively. At 2 years, compared with those in the nonoperative group, patients in the operative group had better ODI (mean difference = -12.98; 95% CI, -16.08 to -9.88; P <.001) and SRS-22 (mean difference = 0.57; 95% CI, 0.45-0.70; P <.001) scores, with mean differences exceeding the minimal detectable measurement difference (MDMD) for ODI (7) and SRS-22 (0.4). Mean differences at 5 years (ODI = -11.25; 95% CI, -15.20 to 7.31; P <.001; SRS-22 = 0.58; 95% CI, 0.44-0.72; P <.001) and 8 years (ODI = -14.29; 95% CI, -17.81 to -10.78; P <.001; SRS-22 = 0.74; 95% CI, 0.57-0.90; P <.001) remained as favorable as at 2 years without evidence of degradation. The treatment-related serious adverse event (SAE) incidence rates for operative patients at 2, 2 to 5, and 5 to 8 years were 22.24, 9.08, and 8.02 per 100 person-years, respectively. At 8 years, operative patients with 1 treatment-related SAE still had significant improvement, with mean treatment differences that exceeded MDMD (ODI = -9.49; 95% CI, -14.23 to -4.74; P <.001; SRS-22 = 0.62; 95% CI, 0.41-0.84; P <.001). Conclusions and Relevance: Results of this nonrandomized clinical trial reveal that, on average, operative treatment for ASLS provided significantly greater clinical improvement than nonoperative treatment at 2-, 5- and 8-year follow-up, with no evidence of deterioration. Operative patients with a treatment-related SAE still maintained greater improvement than nonoperative patients. These findings suggest long-term durability of surgical treatment for ASLS and may prove useful for patient management and counseling. Trial Registration: ClinicalTrials.gov Identifier: NCT00854828.