Age at Surgery and Domain-Specific SRS-22r Outcomes in Documented Adolescent-Onset Idiopathic Scoliosis

STUDY DESIGN: Retrospective two-center surgical cohort with cross-sectional preoperative comparisons and longitudinal postoperative follow-up. OBJECTIVE: To characterize domain-specific associations between age at surgery and preoperative and postoperative Scoliosis Research Society-22 revised (SRS-22r) scores while testing robustness to adult heterogeneity and incomplete follow-up. SUMMARY OF BACKGROUND DATA: Age may relate differently to individual SRS-22r domains, but comparisons of patients operated at different ages cannot establish the effect of earlier surgery. METHODS: The cohort comprised 438 unique patients aged 10-79 years with documented adolescent-onset idiopathic scoliosis; de novo degenerative scoliosis was excluded. Age was modeled continuously, with natural cubic splines and completed-year bands used secondarily. Two- and 5-year analyses included only patients calendar-eligible at the September 28, 2026 data lock. Baseline-adjusted scores, domain-by-age interactions, and inverse-probability-of-follow-up weighting were analyzed. RESULTS: Paired function was available for 93.8% and 85.6% of eligible patients with baseline scores at 2 and 5 years. Older age was not associated with smaller observed functional change. Each 10-year older age was associated with lower baseline-adjusted postoperative function at 2 years (β, -0.196; 95% CI, -0.276 to -0.116) and 5 years (β, -0.160; 95% CI, -0.241 to -0.079; both q<0.001). Weighted estimates were nearly identical (-0.197 and -0.163). No other domain had an adverse age association after false discovery rate control; domain-by-age interactions were significant at both follow-ups (both P<0.001). CONCLUSION: In this predominantly adolescent surgical cohort with a small, selected adult subgroup, older age was associated with lower postoperative function after adjustment for baseline function and measured covariates. These observational findings do not show that operating earlier would improve the outcome of the same patient and should complement, not replace, radiographic and patient-specific decision-making. LEVEL OF EVIDENCE: 3.