1 Department of Biostatistics, Vanderbilt University School of Medicine, Nashville, TN 37232, USA; Center for Asthma Research, Vanderbilt University School of Medicine, Nashville, TN 37232, USA.
2 Department of Biostatistics, Vanderbilt University School of Medicine, Nashville, TN 37232, USA; Department of Medicine, Division of Allergy, Pulmonary and Critical Care Medicine, Vanderbilt University School of Medicine, Nashville, TN 37232, USA; Center for Asthma Research, Vanderbilt University School of Medicine, Nashville, TN 37232, USA.
3 Department of Medicine, Division of Allergy, Pulmonary and Critical Care Medicine, Vanderbilt University School of Medicine, Nashville, TN 37232, USA; Center for Asthma Research, Vanderbilt University School of Medicine, Nashville, TN 37232, USA. Electronic address: tina.hartert@vanderbilt.edu.