Measuring Deterioration in International Classification of Functioning Domains of People With Multiple Sclerosis Who Are Ambulatory

Measures to detect important effects related to physical therapy interventions must be able to detect an important change. The purpose of this study was to select the most responsive physical functioning measures for multiple sclerosis (MS) using the International Classification of Functioning, Disability and Health (ICF) as a framework. The participants were 120 people with MS who were ambulatory from a population-based sample. Physical functioning was assessed by quantitative clinical measures of activities (n=5) and body functions (n=7) and by self-reported performance in self-care, mobility, and domestic life domains in the activities and participation component of the ICF at baseline and 2 years later. A participant's perception of change and a change in Expanded Disability Status Scale (EDSS) scores were used as external criteria in the analysis of the receiver operating characteristic curve and the minimally important change score. The minimal detectable change was calculated as distribution-based responsiveness. According to the external criteria, 51% of the participants showed deterioration as measured by their own perceptions compared with the 26% of the participants who showed deterioration as rated by the clinician. Regardless of the external criterion applied, the measures most responsive to deterioration were self-reported scores in self-care, mobility, and domestic life; distance walked and change in heart rate during a 6-minute walk test; 10-m walk test speeds, stride length, and cadence; repetitive squatting; and Box and Block Test scores. The results show the relative responsiveness of different measures in the subsample who deteriorated and provide data that can facilitate the interpretation of score changes in people with MS who are ambulatory for future studies and in clinical practice.