Study design
extrahepatic biliary strictures
We performed a single-blinded, randomized controlled trial to prove superior sensitivity of the dense Infinity® brush (US Endoscopy, Northeast Ohio, USA. CE 02,112) over the conventional RX cytology® brush (Boston scientific Corporation, Marlborough, MA, USA. CE 616,288) for diagnosing malignant, extrahepatic biliary strictures. The study was performed in the Amsterdam University Medical Centers (location Academic Medical Center and VU Medical Center, Amsterdam), a tertiary care centre in the Netherlands. The study was approved on January 14th, 2016 by the local institutional review board of the Academic Medical Center (approval number METC 2015_240). The independent data safety monitoring board (DSMB) consisted of two gastroenterologists and a clinical epidemiologist. The DSMB evaluated the results of the interim analysis (after 50% of the patients completed follow-up, 