Under the Innovative Medicines Initiative Joint-Undertaking (IMI-JU) framework, the public-private PROactive Consortium developed two Patient Reported Outcome (PRO) instruments to capture physical activity (PA) data in patients with Chronic Obstructive Pulmonary Disease (COPD) in clinical trial settings. One of those tools is the D-PPAC which is supposed to enable daily data collection (recall period of 1 day).