1. Houston Center for Quality of Care & Utilization Studies, Sections of Health Services Research and Gastroenterology at the Michael E. DeBakey Veterans Affairs Medical Center and Baylor College of Medicine, 2002 Holcombe Boulevard, Houston, TX 77030, USA
2. Houston Center for Quality of Care & Utilization Studies, Section of Health Services Research at the Michael E. DeBakey Veterans Affairs Medical Center and Baylor College of Medicine, Houston, TX, USA