1. Center for Health Services Research in Primary Care, Durham Veterans Affairs Health Care System, Durham, North Carolina 27701, USA
2. Department of Population Health Sciences, School of Medicine, Duke University, Durham, North Carolina 27707, USA;
3. Institute of Nursing Science, Department of Public Health, University of Basel, 4056 Basel, Switzerland;
4. Division of Gerontology and Geriatrics, Department of Chronic Diseases, Metabolism, and Ageing, KU Leuven, 3000 Leuven, Belgium
5. Patient Solutions Unit, Medical Evidence Generation Team, Sanofi, 75008 Paris, France
6. Academic Centre for Nursing and Midwifery, Department of Public Health and Primary Care, KU Leuven, 3000 Leuven, Belgium