2015 ISAKOS Biennial Congress ePoster #2424

Minimally Important Differences of the Ases and Worc in Patients Treated Surgically and Non-Surgically for Full Thickness Rotator Cuff Tears

Joel Gagnier, ND, MSc, PhD, Ann Arbor, MI UNITED STATES
Christopher Robbins, PhD, Ann Arbor, MI UNITED STATES
James Carpenter, Ann Arbor, MI UNITED STATES
Asheesh Bedi, MD, Ann Arbor, MI UNITED STATES
Bruce S. Miller, MD, MS, Ann Arbor, MI UNITED STATES

University of Michigan, Ann Arbor, MI, USA

FDA Status Not Applicable

Summary: We gave two patient reported outcome measures, the ASES and WORC to 209 patients with rotator cuff tears and followed them for two years and calculated the minimally important differences.

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Abstract:

Introduction

Rotator cuff tears (RCT) are among the most common disease entities in our aging population. Clinical studies of patients with RCTs include an array of outcome measures, many of which have important drawbacks in their psychometric properties. The minimally important difference (MID) is defined as the smallest change in an outcome measure that is perceived by patients as beneficial or that would result in a change in treatment. The American Shoulder and Elbow Society (ASES) score and the Western Ontario Rotator Cuff index (WORC) are frequently used measures in clinical research for patients with RCTs. The MIDs for these outcome measures has not been established in a homogenous population of patients with rotator cuff tears. The objectives of this research was to establish the MIDs for patients with known rotator cuff tears and to compare these MIDs to patient to patient progress separately for operative versus non-operative management of RCTs.

Methods

In the context of a prospective pragmatic cohort study we included 209 subjects with known full-thickness rotator cuff tears who were followed prospectively for up to 2 years. The WORC and ASES score were collected at baseline, 4, 8, 16, 32, and 48 weeks, 1 year and 2 years. At the final follow-up point patients filled out an end of study form which included several questions regarding change in their condition after treatment. First they were asked following their treatment how they feel overall (better, worse or no change); if they indicated better they were then asked how successful they felt their treatment was on a scale of 1 to 5 (1 indicating not at all successful, 5=totally successful). We then calculated the mean change in the ASES and WORC in those patients indicating minimal change. Next we plotted the MID separately comparing change across time for the operative versus the non-operative groups.

Results

Of the original 209 included patients, a total of 89 patients completed the 2 year follow-up and completed the end of study forms and 196 completed the 64 week follow-up. For those that indicated being minimally better, the change from baseline for the ASES score was -20.57 (-2.94 to -38.20) and for the WORC was 418.60 (70.39 to 766.81); both indicated improvement in outcomes. When converted to the percentage change score the WORC change represented 19.93%. The plots of these new MID values for the ASES and WORC indicate that not only does the operative group improve more than the non-operative group but it does so to an extent that is greater than the MID. The non-operative group also improved across time, but the magnitude did not exceed the MID for either the WORC or the ASES.

Discussion

We found that the ASES and the WORC MIDs in patients with rotator cuff tears is different from that previously reported in the literature and that the operative group change was greater than the non-operative group change. In addition the operative group changed more than the reported MID values than did the non-operative group.