2021 ISAKOS Biennial Congress ePoster
Establishing Minimal Clinically Important Difference In The Shoulder Activity Level Rating Scale After Shoulder Surgery
Darby Adele Houck, BA, Boulder, CO UNITED STATES
Ian L Verbeck, MS, Superior , CO UNITED STATES
Eric C. McCarty, MD, Boulder, CO UNITED STATES
Rachel M. Frank, MD, Aurora, CO UNITED STATES
Michelle Wolcott, MD, Denver, CO UNITED STATES
Adam Seidl, MD, Centennial, CO UNITED STATES
Jonathan T. Bravman, MD, Denver, CO UNITED STATES
University of Colorado School of Medicine; Department of Orthopaedics; Division of Sports Medicine and Shoulder Surgery, Aurora, CO, UNITED STATES
FDA Status Not Applicable
Summary
This is the first study to assess the MCID for the Shoulder Activity Level Rating Scale (MARX) in patients following shoulder surgery.
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Abstract
Background
The Shoulder Activity Level Rating Scale (MARX) is commonly used to predict outcomes of shoulder disorders. The purpose of this study was to establish the minimal clinically important difference (MCID) in MARX activity scores in patients who underwent shoulder surgery.
Methods
Utilizing our institutions prospective outcomes registry, we identified patients who underwent shoulder surgery and completed baseline MARX activity scores. A total of 499 patients that underwent shoulder surgery were included, with 355 patients who underwent rotator cuff repair (RCR), and 144 who underwent total shoulder arthroplasty (TSA). Six patient-reported outcome measures (PROMS) were administered pre- and postoperatively at 3, 6, 12, and 24 months. The change in the PROMS from baseline to the 12-month follow-up was calculated. The MCID was determined with use of the anchor-based and distribution-based techniques.
Results
A total of 499 patients (59.2% male) who underwent shoulder surgery (RCR subgroup, n=355 [63.1% male]; TSA subgroup, n=144 [49.31% male]) were included. The mean age of the combined group was 60.80 (SD: 10.56) years. The RCR subgroup had a mean age of 58.70 (SD: 10.35), while the TSA subgroup had a mean age of 65.97 (SD: 9.30) years. Using the distribution-based method, which was found to be the most reliable, the MCID identified for MARX was 2.36 for the combined group, with MCIDs being 2.27 for the RCR subgroup, and 2.41 for the TSA subgroup. This indicates that an 11.8% (RCR, 11.3%; TSA, 12.1%) increase in the MARX score represents the smallest difference which this specific patient cohort perceives as beneficial. At 12 months after shoulder surgery, the sole significant predictor of obtaining the MCID was whether the patient met the MCID for any PROM in their most recently taken survey for 411 patients in the combined group (OR, 9.53; p=0.031) and 262 patients in the RCR group (OR, 8.91; p=0.043).
Conclusions
This is the first study to assess the MCID for the Shoulder Activity Level Rating Scale (MARX) in patients following shoulder surgery. The estimate of the MCID will facilitate the interpretation and application of this measure of activity level in clinical practice and research.