title: Preprocessing structured clinical data for predictive modeling and decision support. A roadmap to tackle the challenges.
abstract: EHR systems have high potential to improve healthcare delivery and management. Although structured EHR data generates information in machine-readable formats, their use for decision support still poses technical challenges for researchers due to the need to preprocess and convert data into a matrix format. During our research, we observed that clinical informatics literature does not provide guidance for researchers on how to build this matrix while avoiding potential pitfalls.
  
  
  
  This article aims to provide researchers a roadmap of the main technical challenges of preprocessing structured EHR data and possible strategies to overcome them.
  
  
  
  Along standard data processing stages - extracting database entries, defining features, processing data, assessing feature values and integrating data elements, within an EDPAI framework -, we identified the main challenges faced by researchers and reflect on how to address those challenges based on lessons learned from our research experience and on best practices from related literature. We highlight the main potential sources of error, present strategies to approach those challenges and discuss implications of these strategies.
  
  
  
  Following the EDPAI framework, researchers face five key challenges: (1) gathering and integrating data, (2) identifying and handling different feature types, (3) combining features to handle redundancy and granularity, (4) addressing data missingness, and (5) handling multiple feature values. Strategies to address these challenges include: cross-checking identifiers for robust data retrieval and integration; applying clinical knowledge in identifying feature types, in addressing redundancy and granularity, and in accommodating multiple feature values; and investigating missing patterns adequately.
  
  
  
  This article contributes to literature by providing a roadmap to inform structured EHR data preprocessing. It may advise researchers on potential pitfalls and implications of methodological decisions in handling structured data, so as to avoid biases and help realize the benefits of the secondary use of EHR data.
authors.affiliation: José Carlos Ferrão, Rua Irmãos Siemens 1, Ed. 3 Piso 3, 2720-093 Amadora, Portugal, Email address: jose.ferrao@tecnico.ulisboa.pt, Telephone: (+351) 214 178 668, Fax: (+351) 214 178 030.
authors.forename: José Carlos
authors.initials: JC
authors.lastname: Ferrão
authors.forename: Mónica Duarte
authors.initials: MD
authors.lastname: Oliveira
authors.forename: Filipe
authors.initials: F
authors.lastname: Janela
authors.forename: Henrique M G
authors.initials: HM
authors.lastname: Martins
mesh_terms: D057225:Data Mining; D020000:Decision Support Systems, Clinical; D057286:Electronic Health Records; D006801:Humans; D015233:Models, Statistical
keywords: Data mining; clinical decision support; data access; electronic health records and systems; integration and analysis; structured data