1. Department of Environmental Health Sciences, Johns Hopkins Bloomberg School of Public Health, Baltimore, Maryland
2. Department of Biostatistics, Johns Hopkins Bloomberg School of Public Health, Baltimore, Maryland
3. Department of Medicine, Johns Hopkins School of Medicine, Baltimore, Maryland
4. Robert Wood Johnson Foundation Health and Society Scholars Program, University of California, San Francisco, and University of California, Berkeley
5. Center for Health Research, Geisinger Health System, Danville, Pennsylvania
6. Department of Environmental Health Sciences, Johns Hopkins Bloomberg School of Public Health, Baltimore, Maryland3Department of Medicine, Johns Hopkins School of Medicine, Baltimore, Maryland5Center for Health Research, Geisinger Health System, Danville, Pennsylvania