Substantial Variability Exists in Reporting Clinically Significant Outcome Measure Thresholds for Arthroscopic Anterior Cruciate Ligament Reconstruction: A Systematic Review

Purpose: To systematically review the reporting of clinically significant outcome measure (CSO) thresholds and methods for calculating thresholds after anterior cruciate ligament (ACL) reconstruction. Methods: A systematic review of PubMed, Embase, and Web of Science databases was conducted to identify articles that met inclusion criteria from January 1, 2015, to July 7, 2024. Inclusion criteria included studies reporting CSO thresholds including minimal clinically important difference (MCID), substantial clinical benefit (SCB), or patient acceptable symptomatic state (PASS) for patients after ACL reconstruction with minimum 12-month follow-up. The Methodological Index for Non-Randomized Studies criteria were used to assess study quality. Study demographics, patient-reported outcome measures (PROMs), CSO thresholds, and method of CSO calculation were collected. Results: A total of 56 studies (n = 52,292 patients) met the final inclusion criteria. Reported PROMs included International Knee Documentation Committee (n = 35 studies), Knee Injury and Osteoarthritis Outcome score (n = 33 studies), Tegner (n = 20 studies), and Lysholm (n = 19 studies) scores. The PASS was reported in 35 studies, MCID in 30, and SCB in 4. Among the studies that reported PASS, the most used threshold calculation was the ROC-Youden index (71.4%, n = 25/35). In the studies reporting MCID, the most used threshold calculation was the 0.5 standard deviation of mean change method (36.7%, n = 11/30). The most-reported threshold calculation among the SCB studies was the ROC curve analysis (75%, n = 3/4). In studies independently calculating CSOs, the most common methods were 0.5 standard deviations of mean change for MCID (50%, n = 10/20), the ROC-Youden index for PASS (73.3%, n = 11/15), and ROC curve analysis (75.0%, n = 3/4) for SCB. Descriptions of anchor questions were reported in 22 studies (39.3%). Conclusions: Substantial variability exists in the reporting and calculation of MCID, SCB, and PASS for various PROMs after ACL reconstruction. Level of Evidence: Level IV, systematic review of Level II-IV studies.