1. a Division of General Medicine, Department of Medicine , Audie L. Murphy Memorial Veterans Hospital and University of Texas Health Science Center , 7703 Floyd Curl Drive, San Antonio, Texas, 78284, USA
2. b Geriatric Research, Education and Clinical Center , Audie L. Murphy Memorial Veterans Hospital and University of Texas Health Science Center , San Antonio, Texas, USA
3. c Division of General Internal Medicine, Department of Medicine , Audie L. Murphy Memorial Veterans Hospital and University of Texas Health Science Center , San Antonio, Texas, USA
4. d Department of Surgery , Audie L. Murphy Memorial Veterans Hospital and University of Texas Health Science Center , San Antonio, Texas, USA