The Physical Activity and Disability Survey (PADS): reliability, validity and acceptability in people with multiple sclerosis

Objective: To explore the test-retest reliability and construct validity of the standardized Physical Activity and Disability Survey (PADS) and its acceptability to people with multiple sclerosis. Design: Participants completed the PADS twice with seven days between repeated measures, while also wearing an Actical accelerometer. Semi-structured interview questions were used to explore the acceptability of the PADS. Subjects: Thirty participants were recruited from the Multiple Sclerosis Society of Auckland, New Zealand. Mean age of participants was 54 years (range 27-76). Main measures: Physical Activity and Disability Survey (PADS) and Actical accelerometer. Results: A wide range of standardized PADS scores were recorded at each time-point (ranges 6.7-83.3 and 6.7-87.4). While standardized PADS scores between time-points had a high intraclass correlation coefficient of 0.92 (95% confidence interval (0) 0.88, 0.98), Bland-Altman 95% limits of agreement (- 17.4, 17.4) were modest. Accelerometer activity counts were not accurately predicted by standardized PADS scores (wide 95% prediction intervals). Participants reported the PADS was easy to understand and complete, enabling them to give an accurate picture of their physical activity. Conclusions: The PADS appears to be a potentially appropriate measure of activity for people with multiple sclerosis, particularly in terms of the wide range of activities it covers and its ability to detect varying levels of physical activity. We suggest the test-retest reliability and validity of the PADS could be improved with some minor revisions.