Gwon DI, Ko GY, Sung KB, Yoon HK, Shin JH, Hyoung Kim J, Kim J, Oh JY Percutaneous biliary metallic stent placement in patients with unilobar portal vein occlusion caused by advanced hilar malignancy: outcome of unilateral versus bilateral stenting. AJR Am J Roentgenol. 2011 Oct;197(4):795-801. doi: 10.2214/AJR.11.6424.
Inal M, Akgül E, Aksungur E, Seydaoglu G Percutaneous placement of biliary metallic stents in patients with malignant hilar obstruction: unilobar versus bilobar drainage. J Vasc Interv Radiol. 2003 Nov;14(11):1409-16.
Iwano H, Ryozawa S, Ishigaki N, Taba K, Senyo M, Yoshida K, Sakaida I Unilateral versus bilateral drainage using self-expandable metallic stent for unresectable hilar biliary obstruction. Dig Endosc. 2011 Jan;23(1):43-8. doi: 10.1111/j.1443-1661.2010.01036.x. Epub 2010 Nov 30.
Li M, Wu W, Yin Z, Han G [Unilateral versus bilateral biliary drainage for malignant hilar obstruction: a systematic review and meta-analysis]. Zhonghua Gan Zang Bing Za Zhi. 2015 Feb;23(2):118-23. doi: 10.3760/cma.j.issn.1007-3418.2015.02.009. Review. Chinese.
Liberato MJ, Canena JM Endoscopic stenting for hilar cholangiocarcinoma: efficacy of unilateral and bilateral placement of plastic and metal stents in a retrospective review of 480 patients. BMC Gastroenterol. 2012 Aug 9;12:103. doi: 10.1186/1471-230X-12-103.
Interventional studies are often prospective and are specifically tailored to evaluate direct impacts of treatment or preventive measures on disease.
Observational studies are often retrospective and are used to assess potential causation in exposure-outcome relationships and therefore influence preventive methods.
Expanded access is a means by which manufacturers make investigational new drugs available, under certain circumstances, to treat a patient(s) with a serious disease or condition who cannot participate in a controlled clinical trial.
Clinical trials are conducted in a series of steps, called phases - each phase is designed to answer a separate research question.
Phase 1: Researchers test a new drug or treatment in a small group of people for the first time to evaluate its safety, determine a safe dosage range, and identify side effects.
Phase 2: The drug or treatment is given to a larger group of people to see if it is effective and to further evaluate its safety.
Phase 3: The drug or treatment is given to large groups of people to confirm its effectiveness, monitor side effects, compare it to commonly used treatments, and collect information that will allow the drug or treatment to be used safely.
Phase 4: Studies are done after the drug or treatment has been marketed to gather information on the drug's effect in various populations and any side effects associated with long-term use.
