To determine the extent of improvement in the Oswestry Disability Index (ODI) required to achieve patient satisfaction among frail patients undergoing lumbar fusion surgery METHODS: Consecutive patients who underwent lumbar fusion surgery from June 2020 to July 2022 were recruited in this retrospective study. Patient-specific and procedure-specific variables were included. The baseline and 3-month ODI were assessed. Patient satisfaction was assessed at 1 year after surgery. Multivariable logistic regression adjusting age, gender and BMI was conducted to determine the impact of frailty on patient satisfaction. Receiver operating characteristic analysis determined threshold values for relative ODI improvement and postoperative ODI indicative of patient satisfaction.A total of 418 patients were included in the final analysis, with a mean age of 70.4 ± 11.1 years. The median baseline preoperative ODI was 57.5 [37.5-65.0] with a ODI of 17.5 [7.5-27.7] at 3 months after surgery. The median improvement in ODI was 42.5 [22.5-53.1] and the relative ODI improvement was 68.7 [41.2-75.3]. In non/prefrail patients, individuals with higher baseline ODI (OR 1.24, 95% CI 1.04-1.64, p < 0.001) had a significant higher probability of experiencing postoperative satisfaction. However, in frail patients, individuals with lower baseline ODI (OR 0.92, 95% CI 0.87-0.96, p < 0.001) were more prone to experience postoperative satisfaction. In non/prefrail patients, a postoperative ODI score ≤ 26 with a sensitivity of 80% and a specificity of 71% or a relative ODI improvement ≥ 55% with a sensitivity of 74% and a specificity of 68% was associated with patient satisfaction. Accordingly, in frail patients, a postoperative ODI score ≤ 17 with a sensitivity of 75% and a specificity of 65% or a relative ODI improvement ≥ 67% with a sensitivity of 71% and a specificity of 69% was linked to patient satisfaction CONCLUSION: In frail group, patients with lower preoperative ODI were significantly more likely to experience postoperative satisfaction while patients with higher preoperative ODI were significantly more prone to experience postoperative satisfaction in non/prefrail group. In frail group, a relative ODI improvement ≥ 67% or postoperative ODI ≤ 17 indicated patient satisfaction; in non/prefrail group, relative ODI improvement ≥ 55% or postoperative ODI ≤ 26 indicated patient satisfaction.Copyright © 2025. Published by Elsevier Inc.