Defining substantial clinical benefits of PROMIS pain interference in adult spinal deformity patients

As the prevalence of adult spinal deformity (ASD) increases, it is crucial to define patient-centered outcome benchmarks to improve understanding of successful surgical intervention. The Patient-Reported Outcomes Measurement Information System Pain Interference (PROMIS PI) is the gold standard for spine surgery, but substantial clinical benefit (SCB) thresholds specific to ASD patients remain undefined. This study aims to establish PROMIS PI SCB values using fixed and dynamic Oswestry Disability Index (ODI) anchors. This single-center retrospective cohort study included 117 ASD patients who underwent surgery for ASD from 2016 to 2024. PROMIS PI and ODI scores were collected preoperatively and at 6 months postoperatively. The SCB thresholds for PROMIS PI were calculated using both fixed (ODI > 19) and dynamic (≥ 50% improvement) anchors. Optimal cutoffs were identified using receiver operating characteristic (ROC) curves and clinical relevance was assessed using multivariable regressions of the association between the SCB thresholds and PROMIS Physical Function, Depression, and Anxiety scores. PROMIS PI SCB thresholds with a fixed anchor were identified to be 9.6 points (AUC = 0.8563) or a 12.04% improvement when using a dynamic threshold (AUC = 0.8532). When using a dynamic anchor, the SCB thresholds were 8.2 points (AUC = 0.8185) or a 21.24% improvement when using a dynamic threshold (AUC = 0.855). Achieving SCB was associated with significantly greater improvements in physical function (β = 7.1 to 8.6, p < 0.001)) and depression (β=-4.6 to -5.1, p < 0.02) at one year. This is the first study to define ASD-specific SCB thresholds for PROMIS PI. We found that using a 21.24% improvement using a dynamic ODI anchor was a significant and clinically applicable benchmark. These findings will help enhance interpretability of PROMIS PI scores for evaluating surgical outcomes for managing ASD.