Operative vs Nonoperative Treatment for Adult Symptomatic Lumbar Scoliosis at 8-Year Follow-Up

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