Performance measures for upper gastrointestinal endoscopy: a European Society of Gastrointestinal Endoscopy (ESGE) Quality Improvement Initiative - Bisschops, Raf; Areia, Miguel; Coron, Emmanuel; Dobru, Daniela; Kaskas, Bernd; Kuvaev, Roman; Pech, Oliver; Ragunath, Krish; Weusten, Bas; Familiari, Pietro; Domagk, Dirk; Valori, Roland; Kaminski, Michal F.; Spada, Cristiano; Bretthauer, Michael; Bennett, Cathy; Senore, Carlo; Dinis-Ribeiro, Mário; Rutter, Matthew D. (Endoscopy, 2016)