Minimal Clinically Important Differences of Patient-Reported Outcomes Measurement Information System Physical Function in Patients With Tibial Shaft Fracture

Abstract

Objective: To calculate the minimal clinically important differences (MCIDs) of patient-reported outcomes measurement 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: MCIDs were calculated by distribution-based and anchor-based methods, calculated from PROMIS PF scores completed at least at two-time points postoperatively. MCIDs were calculated at different time points including overall, 7–12 weeks, 3–6 months, and 6–24 months. MCIDs 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.