1. National Research and Development Centre for Welfare and Health, Health Services Research Unit, Helsinki and Chydenius Institute, University of Jyväskylä, Kokkola, Finland,
2. National Research and Development Centre for Welfare and Health, Health Services Research Unit, Helsinki
3. Koskela Hospital, Helsinki, Finland
4. Institute of Gerontology and School of Public Health, The University of Michigan and Ann Arbor VA Medical Center, Ann Arbor, Michigan, USA