Minimal important changes in the Constant-Murley score in patients with subacromial pain

Abstract

Objective: The purpose of this study was to determine the minimal important change (MIC) of improvement in the Constant-Murley score in patients with long-standing subacromial pain and in subgroups of patients with subacromial pain with and without rotator cuff ruptures.

Method: The MIC was estimated by the anchor-based MIC distribution method, which integrates an anchor- and distribution-based approach: the optimal cutoff point of the receiver operating characteristic curve (MICROC) and the 95% limit cutoff point (MIC95% limit). The study population consisted of 93 patients included in a randomized clinical trial evaluating the effect of a specific exercise strategy.

Results: The MICROC was found at a mean change of 17 points in the Constant-Murley score, which corresponds to a sensitivity of 91% and a specificity of 79%. The MIC95% limit was found at a mean change of 24 points. In the subgroup analysis, the MICROC was found at a mean change of 19 points and the MIC95% limit at 18 points in patients with an intact rotator cuff. In patients with rotator cuff ruptures, the MICROC was found at a mean change of 15 points and the MIC95% limit at 30 points.

Conclusion: The Constant-Murley score is able to detect the MIC in individual patients with long-standing subacromial pain when the rotator cuff is intact. The estimated MIC values could be used as an indication for relevant changes in the Constant-Murley score in clinical practice and guide the clinician in how to interpret the results of specific treatments.

Keywords: Constant-Murley score; Subacromial pain; anchor-based methods; clinical important change; distribution-based methods; minimal important change.