Setting and procedure

The population-based Gerontological Regional Database (GERDA) cohort study was initiated to investigate the health/disease status of very old people and factors leading to good aging in this population. Half of all 85-year-olds, all 90-year-olds, and all participants aged at least 95 years in selected municipalities of Västerbotten County, northern Sweden, were invited to participate. The first round of data collection was performed in an urban municipality in 2000 and in five adjacent rural municipalities in 2002. A second round of data collection was performed in 2005 and 2007 with the same inclusion criteria, meaning that all surviving past participants were eligible for reparticipation in older age groups. A third data collection was performed in 2010 and 2012.

Eligible individuals were informed about the study by postal mail and then contacted by telephone. Participants underwent assessments and physical tests during visits in residences and institutional care facilities. Medical charts were reviewed, and relatives and institutional care staff were contacted for supporting information when needed. Oral consent to participate was acquired during telephone calls and home visits. When cognitive impairment was suspected, a relative was also asked to provide consent. Examiners were nurses, physical therapists, physicians, and medical students. The Regional Ethical Review Board of Umeå/Sweden approved the study (2014-221-31m).