The Hospital Episodes Statistics database (HES) contains information on all admissions to an NHS hospital in England, with over 12 million new records added each year. It is managed by the NHS information center and is available for research with ethical approval. All NHS hospitals within England are required to contribute to the database. There are currently 168 acute trusts in England; however, each of these trusts can manage more than 1 hospital, and over time trusts can merge and split. Over the course of our study, Crizotinib cost approximately

150–200 providers were contributing to the database. The available data consist of a number of records for each admission, which are called episodes. Each episode represents the time period of the admission that a patient was under the clinical care of a particular consultant team during their inpatient stay. A unique patient identifier allows all records for each patient to be identified

and linked together. Each episode’s time span is defined with a start and finish date as well as being assigned an admission and discharge date for the whole period Selumetinib solubility dmso of the inpatient stay. Each episode will have up to 14 diagnoses coded using International Classification of Diseases 10th revision (ICD-10); and up to 12 procedures coded using the United Kingdom Tabular List of the Classification of Surgical Operations and Procedures (OPCS) (version OPCS4). This database has been linked to the Office of National Statistics (ONS) death register since 1998. All admissions older than 15 years Methocarbamol (chosen to be consistent with the lower age limit of previous British Society of Gastroenterology (BSG) audits of mortality in gastrointestinal hemorrhage8 and 9), which had an ICD-10 code for upper gastrointestinal hemorrhage, with a date of hemorrhage between January 1, 1999, and December

31, 2007, were extracted. Data were available for 2008 to allow complete follow-up of mortality for admissions occurring in December 2007. Upper gastrointestinal hemorrhage was defined as an ICD-10 code that specifically implied either variceal gastrointestinal hemorrhage: esophageal varices with hemorrhage (I85.0) or nonvariceal hemorrhage: Mallory–Weiss syndrome (K22.6), esophageal hemorrhage (K22.8) acute, or chronic gastric ulcer with hemorrhage including perforation with hemorrhage (K25.0, K25.2, K25.4, K25.6), acute or chronic duodenal ulcer with hemorrhage including perforation with hemorrhage (K26.0, K26.2, K26.4, K26.6), acute or chronic peptic ulcer with hemorrhage including perforation with hemorrhage (K27.0, K27.2, K27.4, K27.6), acute or chronic gastrojejunal ulcer with hemorrhage including perforation with hemorrhage (K28.0, K28.2, K28.4, K28.6), hematemesis (K92.0), melena (K92.1), or unspecified gastrointestinal hemorrhage (K92.2). This ICD-10 code list has previously been used in hospital data.