Minimal Clinically Important Difference (MCID) and Long-Term Prospective Validation of the AO Spine PROST (Patient Reported Outcome Spine Trauma)

Study design Prospective observational multicenter cohort study. Objectives To determine Minimal Clinically Important Difference (MCID) of AO Spine PROST (Patient Reported Outcome Spine Trauma) and conducting a long-term prospective validation. Methods Data were collected from a prospective observational international multicenter cohort study. Adults (18-65) with acute thoracolumbar (TL) burst fractures without neurologic deficits were enrolled, and followed for up to 2 years. Patients completed the AO Spine PROST, Oswestry Disability Index (ODI), EQ-5D, and Pain NRS. Characteristics were analyzed using descriptive statistics, MCID for PROST with distribution-based approach using the standard deviation (SD) of change in scores. Floor and ceiling effects were also evaluated. Internal consistency (Cronbach’s alpha, item-total correlation coefficient (ITCC) and pairwise Spearman correlation), construct validity (Pearson correlations (r s ) with ODI, EQ-5D, Pain NRS), and responsiveness (effect sizes (ES) and standardized response mean (SRM)) were assessed. Results Ninety-three patients were included. MCID for a moderate change (0.5*SD) in PROST score was 10.6. No floor or ceiling effects were observed. Internal consistency was high (Cronbach’s α = 0.9-1.0 and acceptable ITCC). PROST scores strongly correlated with ODI (rs = −0.67 to −0.89; P < .001), but correlations with EQ-5D were weak (r s = −0.29 to 0.05; P > .005), except at 1-year follow-up. No consistent pattern was found with Pain NRS. Responsiveness was very good (ES = 3.2, SRM = 3.1; P < .001). Conclusions The AO Spine PROST identified an MCID of 10.6 as indicative of a moderate clinically meaningful change. The instrument also showed strong internal consistency, construct validity, and excellent responsiveness in long-term follow-up.