LAUSR

OBJECTIVE Calculate the minimal clinically important differences (MCID) of Patient Reported Outcome Information System Physical Function (PROMIS PF) scores for patients with operatively treated tibial shaft fractures. DESIGN Retrospective Cohort Study. SETTING A Level 1 trauma center. PATIENTS All operatively treated tibial shaft fractures identified by Current Procedural Terminology codes. INTERVENTION Enrolled patients treated acutely with operative fixation of their tibia. MAIN OUTCOME MEASUREMENTS MCID's were calculated by distribution-based and anchor-based methods, calculated from PROMIS PF scores completed at least at two-time points postoperatively. MCID's were calculated at different time points including overall, 7-12 weeks, 3-6 months, and 6-24 months. MCID's were calculated for different subgroups including open fractures, closed fractures, any complications, and no complications. RESULTS MCID for PROMIS PF scores was 5.7 in the distribution-based method and 7.84 (SD 18.65) in the anchor-based method. At 6-24 postoperatively, the months the distribution-based MCID was 5.95 from a postoperative baseline 27.83 (8.74) to 42.85 (9.61),P<0.001. At 6-24 months the anchor-based MCID was 10.62 with a score difference between the improvement group of 16.03 (10.73) and the no improvement group of 5.41 (15.75), P<0.001. Patients with open fractures (distribution-based 6.22 and anchor-based 8.05) and any complications (distribution-based 5.71 and anchor-based 9.29) had similar or higher MCIDs depending on the methodology used than the overall cohort MCIDs. CONCLUSION This study identified distribution-based MCID of 5.7 and anchor-based MCID of 7.84 calculated from PROMIS PF scores in operative tibial shaft fractures. Distribution-based methods yielded smaller MCIDs than anchor-based methods. These MCID scores provide a standard to compare clinical and investigational outcomes. LEVEL OF EVIDENCE Prognostic Level IV. See Instructions for Authors for a complete description of levels of evidence.