Validity of peptic ulcer disease and upper gastrointestinal bleeding diagnoses in administrative databases : a systematic review protocol
INTRODUCTION: Administrative healthcare databases are useful to investigate the epidemiology, health outcomes, quality indicators and healthcare utilisation concerning peptic ulcers and gastrointestinal bleeding, but the databases need to be validated in order to be a reliable source for research. The aim of this protocol is to perform the first systematic review of studies reporting the validatio