1. University of Vermont Larner College of Medicine, Burlington, Vermont 05446, USA
2. Department of Epidemiology, University of Alabama at Birmingham, Birmingham, Alabama 35233, USA
3. Department of Medicine, University of Vermont Larner College of Medicine, Burlington, Vermont 05405, USA
4. Department of Biostatistics, University of Alabama at Birmingham, Birmingham, Alabama 35233, USA
5. Department of Epidemiology & Biostatistics, Dornsife School of Public Health, Drexel University, Philadelphia, Pennsylvania 19104, USA
6. SphingoTec GmbH, 16761 Hennigsdorf, Germany
7. Department of Pathology and Laboratory Medicine, University of Vermont Larner College of Medicine, Burlington, Vermont 05446, USA