The minimal clinically important difference of the Participation Measurement Scale in chronic stroke.

Background: The Participation Measurement Scale (PM-Scale) is an International Classification of Functioning, Disability and Health-based and Rasch-built scale developed specifically to assess participation in people with stroke. Objectives: Our study aimed to estimate the minimal clinically important difference (MCID) for the PM-Scale. Method: We performed a secondary analysis of data from the 'Circuit walking, balance, cycling and strength training' trial. Participants underwent mixed and collective physical activities or sociocultural activities for 12 weeks, and participation data were collected before and after the interventions. The activity limitations (ACTIVLIM)-Stroke scale was used as the anchor of importance. The MCID for the PM-Scale was estimated using receiver operating characteristic (ROC) curves and the Youden index. Results: Data were collected from 46 people with chronic stroke, of which 22% were female, with median (Percentile 25, Percentile 75) age of 54 (44; 60) years, and time since stroke is 24 (11; 37) months. For all participants, the PM-Scale measures range from -2.98 logits to 5.02 logits. The area under the curve (AUC) for the receiver operating characteristic (ROC)-analysis was 0.74 yielding an estimated MCID of 1.98 logit for the PM-Scale. Conclusion: Our study estimated the MCID of the PM-Scale at 1.98 logit, enabling a more precise interpretation of the outcome in the clinical and research settings. Clinical implications: An improvement of at least 1.98 logit on the PM-Scale is required to induce a clinical change in the independence in activities of daily living in people with chronic stroke.