Minimal important change and responsiveness of the arabic patient-specific functional Scale in patients with upper extremity musculoskeletal disorders.

Abstract

To assess the responsiveness of the Arabic Patient-Specific Functional Scale (PSFS) and to determine its minimal important change (MIC) for improvement in upper extremity function. A total of 115 participants with upper extremity musculoskeletal disorders were included. The PSFS, Disabilities of the Arm, Shoulder, and Hand (DASH), global assessment of function (GAF), and numeric pain rating scale (NPRS), were assessed at baseline and follow-up. Responsiveness was examined by testing seven pre-defined hypotheses and the MIC was determined using the predictive modeling method (MIC_pred) and the receiver operating curve method (MIC_ROC). The PSFS change scores demonstrated significant correlations with the global rating of change (<i>r</i> = 0.75), with change scores in DASH (<i>r</i> = 0.76), GAF (<i>r</i> = 0.62), NPRS (<i>r</i> = 0.66), large effect size (ES = 2.34, SRM = 1.63) in improved individuals, and area under the ROC curve of 0.91. The MIC_ROC, MIC_pred, and adjusted MIC_pred for proportion of improved participants were 1.71, 1.98, and 2.15 points, respectively, and that the value of MIC was not dependent on baseline status. The Arabic PSFS showed sufficient responsiveness in detecting changes in upper extremity function over time. The adjusted MIC_pred is recommended to be used as the MIC value in patients with upper extremity musculoskeletal disorders.