title: Harmonization process for the identification of medical events in eight European healthcare databases: the experience from the EU-ADR project.
abstract: OBJECTIVE
  Data from electronic healthcare records (EHR) can be used to monitor drug safety, but in order to compare and pool data from different EHR databases, the extraction of potential adverse events must be harmonized. In this paper, we describe the procedure used for harmonizing the extraction from eight European EHR databases of five events of interest deemed to be important in pharmacovigilance: acute myocardial infarction (AMI); acute renal failure (ARF); anaphylactic shock (AS); bullous eruption (BE); and rhabdomyolysis (RHABD).
  
  
  METHODS
  The participating databases comprise general practitioners' medical records and claims for hospitalization and other healthcare services. Clinical information is collected using four different disease terminologies and free text in two different languages. The Unified Medical Language System was used to identify concepts and corresponding codes in each terminology. A common database model was used to share and pool data and verify the semantic basis of the event extraction queries. Feedback from the database holders was obtained at various stages to refine the extraction queries.
  
  
  METHODS
  Standardized and age specific incidence rates (IRs) were calculated to facilitate benchmarking and harmonization of event data extraction across the databases. This was an iterative process.
  
  
  RESULTS
  The study population comprised overall 19 647 445 individuals with a follow-up of 59 929 690 person-years (PYs). Age adjusted IRs for the five events of interest across the databases were as follows: (1) AMI: 60-148/100 000 PYs; (2) ARF: 3-49/100 000 PYs; (3) AS: 2-12/100 000 PYs; (4) BE: 2-17/100 000 PYs; and (5) RHABD: 0.1-8/100 000 PYs.
  
  
  CONCLUSIONS
  The iterative harmonization process enabled a more homogeneous identification of events across differently structured databases using different coding based algorithms. This workflow can facilitate transparent and reproducible event extractions and understanding of differences between databases.
authors.affiliation: LESIM, ISPED, University Bordeaux Segalen, Bordeaux, France. avillach@mac.com
authors.forename: Paul
authors.initials: P
authors.lastname: Avillach
authors.forename: Preciosa M
authors.initials: PM
authors.lastname: Coloma
authors.forename: Rosa
authors.initials: R
authors.lastname: Gini
authors.forename: Martijn
authors.initials: M
authors.lastname: Schuemie
authors.forename: Fleur
authors.initials: F
authors.lastname: Mougin
authors.forename: Jean-Charles
authors.initials: JC
authors.lastname: Dufour
authors.forename: Giampiero
authors.initials: G
authors.lastname: Mazzaglia
authors.forename: Carlo
authors.initials: C
authors.lastname: Giaquinto
authors.forename: Carla
authors.initials: C
authors.lastname: Fornari
authors.forename: Ron
authors.initials: R
authors.lastname: Herings
authors.forename: Mariam
authors.initials: M
authors.lastname: Molokhia
authors.forename: Lars
authors.initials: L
authors.lastname: Pedersen
authors.forename: Annie
authors.initials: A
authors.lastname: Fourrier-Réglat
authors.forename: Marius
authors.initials: M
authors.lastname: Fieschi
authors.forename: Miriam
authors.initials: M
authors.lastname: Sturkenboom
authors.forename: Johan
authors.initials: J
authors.lastname: van der Lei
authors.forename: Antoine
authors.initials: A
authors.lastname: Pariente
authors.forename: Gianluca
authors.initials: G
authors.lastname: Trifirò
mesh_terms: D016907:Adverse Drug Reaction Reporting Systems / Q000592:standards*; D019985:Benchmarking; D016208:Databases, Factual / Q000592:standards*; D005060:Europe; D006801:Humans; D015994:Incidence; D033181:Information Dissemination; D016247:Information Storage and Retrieval; D007391:International Cooperation; D008498:Medical Record Linkage; D016347:Medical Records Systems, Computerized / Q000592:standards*; D011358:Product Surveillance, Postmarketing / Q000592:standards; D012015:Reference Standards; D017432:Unified Medical Language System