Factors associated with failure to achieve Scoliosis Research Society-22r minimal clinically important difference despite achieving optimal global alignment in adult spinal deformity surgery

Purpose: To identify factors associated with failure to achieve the minimal clinically important difference (MCID) in the Scoliosis Research Society-22r (SRS-22r) despite achieving optimal global alignment in adult spinal deformity (ASD) surgery. Methods: This study analyzed consecutive patients who underwent ≥ 5-level fusion for ASD and achieved optimal global alignment at a minimum of 2-year follow-up. Patients were divided into two groups based on whether they reached the MCID threshold (1.05) for the SRS-22r subtotal score. Demographic, surgical, radiographic, and mechanical complication data were compared between the groups. Multivariate logistic regression analysis was performed to identify independent predictors of MCID failure. Results: A total of 259 patients were included in this study (female, 88.0%; mean age, 69.0 years; mean follow-up duration, 36.5 months). At the final follow-up, 117 patients (45.2%) failed to achieve the SRS-22r MCID. Multivariate analysis identified a high preoperative SRS-22r pain score (odds ratio [OR] = 1.988, P = 0.003) and high preoperative self-image score (OR = 2.597, P = 0.006) as independent predictors of MCID failure. The cutoff values for preoperative pain and self-image scores were 2.50 and 1.70, respectively (area under the curve [AUC] = 0.674 for pain subdomain; AUC = 0.656 for self-image subdomain). Conclusions: Despite achieving optimal global alignment, nearly half of the patients (45.2%) failed to reach the MCID in the SRS-22r score. Higher preoperative SRS-22r pain and self-image scores were significant predictors of failure. Therefore, these two factors should be primary considerations in surgical decision-making to improve patient-reported outcomes.