1. Chronic Disease Research Group; Minneapolis Medical Research Foundation; Minneapolis MN USA
2. Center for Observational Research; Amgen, Inc.; Thousand Oaks CA USA
3. Department of Epidemiology, Gillings School of Global Public Health; University of North Carolina at Chapel Hill; Chapel Hill NC USA
4. Department of Medicine; University of Minnesota; Minneapolis MN USA
5. RTI Health Solutions; Research Triangle Park NC USA
6. Department of Epidemiology and Medicine; Boston University Medical Center; Boston MA USA