Authors Contributions: Mr Witlox had full access to all the data in the study and takes responsibility for the integrity of the data and the accuracy of the data analysis.
Study concept and design: van Gool, Witlox.
Acquisition of data: Witlox, Eurelings.
Analysis and interpretation of data: van Gool, Witlox, Eurelings, Eikelenboom, de Jonghe, Kalisvaart.
Drafting of the manuscript: Witlox, van Gool.
Critical revision of the manuscript for important intellectual content: van Gool, Witlox, Eikelenboom, de Jonghe, Eurelings, Kalisvaart.
Statistical analysis: Witlox, van Gool.
Administrative, technical, or material support: Witlox, van Gool, Eurelings.
Study supervision: van Gool, Eikelenboom, de Jonghe, Kalisvaart.
Financial Disclosures: None reported.
Additional Contributions: We thank all investigators for supplying additional information for this meta-analysis and particularly the following investigators: Giuseppe Bellelli, MD (Department of Rehabilitation and Aged Care, Ancelle Della Carità Hospital, Brescia, Italy), Jim George, MD (North Cumbria University Hospitals, Carlisle, England), Frederick Sieber, MD (Department of Anesthesiology and Critical Care Medicine, Johns Hopkins Medical Institutions, Baltimore, Maryland), Koen Milisen, PhD (Center for Health Services and Nursing Research, Catholic University Leuven, Leuven, Belgium; Division of Geriatric Medicine, Department of Internal Medicine, University Hospitals Leuven, Leuven, Belgium), Melissa Andrew, MD (Division of Geriatric Medicine, Dalhousie University, Halifax, Nova Scotia, Canada), Andrea Giusti, MD (Department of Gerontology, Galliera Hospital, Genova, Italy), Barbara van Munster, MD, PhD (Department of Medicine, Academic Medical Centre, University of Amsterdam), Ritz Kakuma, PhD (Health Systems Research and Consulting Unit, Centre for Addiction and Mental Health, Dalla Lana School of Public Health, University of Toronto, Toronto, Ontario, Canada), Dimitrios Adamis, MD (Consultant in Old Age Psychiatry, Research and Academic Institute of Athens, Greece), Birgitta Olofsson, PhD (Department of Nursing, Umeå University, Umeå, Sweden), Horst Bickel, PhD (Department of Psychiatry and Psychotherapy, Technischen Universität München, München, Germany), L. Joseph Melton III, MD, PhD (College of Medicine, Mayo Clinic, Rochester, Minnesota), Kaisu Pitkälä, MD, PhD (Unit of General Practice, Helsinki University Central Hospital, Helsinki, Finland), and Gianluca Isaia, MD (Department of Medical and Surgical Disciplines, Geriatric Section, San Giovanni Battista Hospital, University of Torino, Italy). No compensation was given to any of these investigators for supplying additional information to us.