CARING FOR PATIENT DATA: Clinimetrics of the interRAI Acute Care as comprehensive geriatric assessment The interRAI-portfolio is an internationally wide-spread method of comprehensive geriatric assessment (www.interRAI.org). This standardized method was the first to develop an integrated health system containing a variety of setting-specific assessment instruments. The instruments are built on a core set of standardized items allowing health professionals to share a common patient file which facilitates data transfer in transitional care. This study aims to determine the clinimetric values of the interRAI Acute Care instrument tailored for acute care of older persons in a variety of clinical settings (various ward types) and for a variety of user profiles (e.g., physicians, nurses, allied health professionals, social services). The ultimate goal of clinimetric studies is to generate high-quality patient data that are sufficiently valid, reliable and responsive. When integrated in eHealth applications, it contributes maximally to better care, reliable and accurate communication between health professionals, evidence-based management, valid research, solid epidemiological knowledge and well-grounded policy for the care of older persons. This study is in agreement with the recent federal policy concerning the Care Program for Geriatric Patients (Royal Decree 29-01-2007).