1. Department of Pharmacology and Toxicology, University of Louisville Health Sciences Center, Louisville, KY, USA;
2. Department of Mathematics, Illinois State University, Normal, IL, USA;
3. Center for Outcomes Research, University of Illinois College of Medicine at Peoria, Peoria, IL, USA;
4. Center for Pharmacoepidemiology & Pharmacoeconomic Research, University of Illinois College of Pharmacy at Chicago, IL, USA;
5. Gastroenterology, OSF Saint Francis Medical Center, Peoria, IL, USA