The purpose of this study was to validate a new interview-administered physical activity questionnaire (Assessment of Physical Activity in Frail Older People; APAFOP) in older people with and without cognitive impairment. The authors assessed feasibility, validity, and test–retest reliability in 168 people (n = 78 with, n = 88 without cognitive impairment). Concurrent validity was assessed against an inertia-based motion sensor and an established questionnaire. Sensitivity to change was tested in an ongoing study in patients with mild to moderate dementia (n = 81). Assessment of physical activity by the APAFOP and the motion sensor correlated well in the total sample (TS; p = .705), as well as in the subsamples with cognitive impairment (CI; p = .585) and without CI (p = .787). Excellent feasibility with an acceptance rate of 100%, test–retest reliability (intraclass correlation coefficients ranging from .973 (TS) to .975 (CI) to .966 (no CI), and sensitivity to change (effect sizes: 0.35–1.47) were found in both subsamples.
Hauer and Schwenk are with the Bethanien-Krankenhaus-Geriatric Center, University of Heidelberg, Heidelberg, Germany. Lord is with the Prince of Wales Medical Research Institute, University of New South Wales, Sydney, Australia. Lindemann is with the Dept. of Clinical Gerontology, Robert Bosch Krankenhaus, Stuttgart, Germany. Lamb is with the Warwick Clinical Trials Unit Health Sciences Research Institute, University of Warwick, Warwick, UK. Aminian is with the Laboratory for Movement Analysis and Measurement, Lausanne Federal Poytechnical School, Lausanne, Switzerland.