Annegarn J, Spruit MA, Uszko-Lencer NHMK, Vanbelle S, Savelberg HHCM, Schols AMWJ, Wouters EFM, Meijer K. Objective physical activity assessment in patients with chronic organ failure: a validation study of a new single-unit activity monitor. OBJECTIVE: To validate a new activity monitor (CAM) in patients with chronic organ failure during 1 hour of unconstrained activity assessment. DESIGN: A validation study in which participants wore a CAM (placed on the thigh) for 1 hour while they were videotaped. Participants were instructed to continue their normal daily routine at the rehabilitation center. SETTING: CIRO+, A Centre of Expertise for Chronic Organ Failure. PARTICIPANTS: Chronic organ failure patients (N=10) with a large range of functional exercise capacity. INTERVENTIONS: Not applicable. MAIN OUTCOME MEASURE: Agreement in time spent on activities and postures according to video and CAM. RESULTS: Cohen kappa coefficients for transient events resulted in an almost perfect agreement (0.85+/-0.08) between the CAM and video. CONCLUSIONS: The CAM is a promising single-sensor unobtrusive tool for providing accurate data on the type and duration of daily activities in the home environment of patients with chronic organ failure.