1. Department of Public Health, University of Massachusetts Lowell , Lowell, Massachusetts , USA
2. Oregon Health & Science University - Portland State University School of Public Health , Portland, Oregon , USA
3. Cecil G. Sheps Center for Health Services Research, University of North Carolina at Chapel Hill , Chapel Hill, North Carolina , USA
4. School of Social Work, University of North Carolina at Chapel Hill , Chapel Hill, North Carolina , USA
5. Center for Gerontology & Healthcare Research, School of Public Health, Brown University , Providence, Rhode Island , USA
6. Institute on Aging, College of Urban and Public Affairs, Portland State University , Portland, Oregon , USA
7. Department of Family Medicine, School of Medicine, University of North Carolina at Chapel Hill , Chapel Hill, North Carolina , USA
8. School of Social and Political Science, University of Edinburgh , Edinburgh , UK
9. School of Nursing, Johns Hopkins University , Baltimore, Maryland , USA