title: Using information theory to identify redundancy in common laboratory tests in the intensive care unit.
abstract: BACKGROUND
  Clinical workflow is infused with large quantities of data, particularly in areas with enhanced monitoring such as the Intensive Care Unit (ICU). Information theory can quantify the expected amounts of total and redundant information contained in a given clinical data type, and as such has the potential to inform clinicians on how to manage the vast volumes of data they are required to analyze in their daily practice. The objective of this proof-of-concept study was to quantify the amounts of redundant information associated with common ICU lab tests.
  
  
  METHODS
  We analyzed the information content of 11 laboratory test results from 29,149 adult ICU admissions in the MIMIC II database. Information theory was applied to quantify the expected amount of redundant information both between lab values from the same ICU day, and between consecutive ICU days.
  
  
  RESULTS
  Most lab values showed a decreasing trend over time in the expected amount of novel information they contained. Platelet, blood urea nitrogen (BUN), and creatinine measurements exhibited the most amount of redundant information on days 2 and 3 compared to the previous day. The creatinine-BUN and sodium-chloride pairs had the most redundancy.
  
  
  CONCLUSIONS
  Information theory can help identify and discourage unnecessary testing and bloodwork, and can in general be a useful data analytic technique for many medical specialties that deal with information overload.
authors.affiliation: School of Public Health and Health Systems, University of Waterloo, Waterloo, Canada. joon.lee@uwaterloo.ca.
authors.forename: Joon
authors.initials: J
authors.lastname: Lee
authors.affiliation: Department of Medicine & Critical Care Program, Queen's University, Kingston, Canada.
authors.forename: David M
authors.initials: DM
authors.lastname: Maslove
mesh_terms: D019411:Clinical Laboratory Techniques / Q000592:standards*; D016208:Databases, Factual / Q000706:statistics & numerical data*; D006801:Humans; D007257:Information Theory; D007362:Intensive Care Units / Q000592:standards*; D019564:Unnecessary Procedures / Q000592:standards*