Construct validity of the Actiwatch‐2 for assessing movement in people with profound intellectual and multiple disabilities

BACKGROUND: Valid measures to assess either small or assisted performed movements of people with profound intellectual and multiple disabilities (PIMD) are required. We analysed the construct validity of the Actiwatch‐2 to assess movement in people with PIMD. METHOD: Twenty‐two persons with PIMD were video recorded while wearing an Actiwatch‐2. We used 15s‐partial‐interval recording to record upper body movement, body position and activity situation. Multilevel analyses were used to evaluate if the Actiwatch‐2, based on produced counts, could detect changes in these factors. RESULTS: The presence versus absence of upper body movement and an activity situation in which participants were involved versus not involved resulted in significantly higher counts, with a large variety in predicted counts between participants. No relationship between body position and counts was found. CONCLUSIONS: The Actiwatch‐2 seems able to assess obvious upper body movement in people with PIMD, and whether there is involvement in an activity situation.