The MCID of the PROMIS physical function instrument for operatively treated tibial plateau fractures.

introductionUnderstanding minimal clinically important differences (MCID) in patient reported outcome measurement are important in improving patient care. The purpose of this study was to determine the MCID of Patient-Reported Outcome Measurement System (PROMIS) Physical Function (PF) domain for patients who underwent operative fixation of a tibial plateau fracture.

methodsAll patients with tibial plateau fractures that underwent operative fixation at a single level 1 trauma center were identified by Current Procedural Terminology codes. Patients without PROMIS PF scores or an anchor question at two-time points postoperatively were excluded. Anchor-based and distribution-based MCIDs were calculated.

resultsThe MCID for PROMIS PF scores was 4.85 in the distribution-based method and 3.93 (SD 14.01) in the anchor-based method. There was significantly more improvement in the score from the first postoperative score (<7 weeks) to the second postoperative time (<78 weeks) in the improvement group 10.95 (SD 9.95) compared to the no improvement group 7.02 (SD 9.87) in the anchor-based method (P < 0.001). The percentage of patients achieving MCID at 7 weeks, 3 months, 6 months, and 1 year were 37-42 %, 57-62 %, 80-84 %, and 95-87 %, respectively. DISCUSSION: This study identified MCID values for PROMIS PF scores in the tibial plateau fracture population. Both MCID scores were similar, resulting in a reliable value for future studies and clinical decision-making. An MCID of 3.93 to 4.85 can be used as a clinical and investigative standard for patients with operative tibial plateau fractures.