This prospective, observational study (UMIN 000007762) was approved by the Ethics Committees of Gunma University Faculty of Medical Science (Maebashi, Japan), National Numata Hospital (Numata, Japan), Maebashi Kyoritsu Hospital (Maebashi, Japan), and Heisei Hidaka Clinic (Takasaki, Japan). This study was started on April 10, 2012 and completed on November 30, 2012.