title: Cognitive complexity of the medical record is a risk factor for major adverse events.
abstract: BACKGROUND
  Patients in tertiary care hospitals are more complex than in the past, but the implications of this are poorly understood as "patient complexity" has been difficult to quantify.
  
  
  OBJECTIVE
  We developed a tool, the Complexity Ruler, to quantify the amount of data (as bits) in the patient’s medical record. We designated the amount of data in the medical record as the cognitive complexity of the medical record (CCMR). We hypothesized that CCMR is a useful surrogate for true patient complexity and that higher CCMR correlates with risk of major adverse events.
  
  
  METHODS
  The Complexity Ruler was validated by comparing the measured CCMR with physician rankings of patient complexity on specific inpatient services. It was tested in a case-control model of all patients with major adverse events at a tertiary care pediatric hospital from 2005 to 2006.
  
  
  METHODS
  The main outcome measure was an externally reported major adverse event. We measured CCMR for 24 hours before the event, and we estimated lifetime CCMR.
  
  
  RESULTS
  Above empirically derived cutoffs, 24-hour and lifetime CCMR were risk factors for major adverse events (odds ratios, 5.3 and 6.5, respectively). In a multivariate analysis, CCMR alone was essentially as predictive of risk as a model that started with 30-plus clinical factors.
  
  
  CONCLUSIONS
  CCMR correlates with physician assessment of complexity and risk of adverse events. We hypothesize that increased CCMR increases the risk of physician cognitive overload. An automated version of the Complexity Ruler could allow identification of at-risk patients in real time.
authors.affiliation: Senior Associate in the Department of Otolaryngology at Boston Children's Hospital and Associate Professor in the Department of Otology and Laryngology at Harvard Medical School in MA. david.roberson@childrens.harvard.edu.
authors.forename: David
authors.initials: D
authors.lastname: Roberson
authors.affiliation: Cognitive Psychology Consultant at the Institute for Knowledge Design, LLC, in Arlington, MA. mikeroe@msn.com.
authors.forename: Michael
authors.initials: M
authors.lastname: Connell
authors.affiliation: Transplant Coordinator in the Department of Cardiology at Boston Children's Hospital in MA. shay.dillis@cardio.chboston.org.
authors.forename: Shay
authors.initials: S
authors.lastname: Dillis
authors.affiliation: Biostatistician in the Department of Cardiology at Boston Children's Hospital in MA. kimberlee.gauvreau@cardio.chboston.org.
authors.forename: Kimberlee
authors.initials: K
authors.lastname: Gauvreau
authors.affiliation: Administrative Assistant III in the Department of Otolaryngology and Communication Enhancement at Boston Children's Hospital in MA. rebecca.gore@childrens.harvard.edu.
authors.forename: Rebecca
authors.initials: R
authors.lastname: Gore
authors.affiliation: Program Manager in Quality Improvement for the United Hospital Fund in New York, NY. elaina1026@gmail.com.
authors.forename: Elaina
authors.initials: E
authors.lastname: Heagerty
authors.affiliation: Senior Vice President and Chief Safety and Quality Officer for the Department of Patient Safety and Quality and the Department of Cardiology for Boston Children's Hospital in MA. kathy.jenkins@cardio.chboston.org.
authors.forename: Kathy
authors.initials: K
authors.lastname: Jenkins
authors.affiliation: Biostatistician in the Departments of Clinical Science, Epidemiology, and Research for Fresenuis Medical Care North America in Waltham, MA. linma424@yahoo.com.
authors.forename: Lin
authors.initials: L
authors.lastname: Ma
authors.affiliation: Program Manager for the Division of Interventional Cardiology at Boston Scientific Corporation in Natick, MA. amy.britt@bsci.com.
authors.forename: Amy
authors.initials: A
authors.lastname: Maurer
authors.affiliation: Medical Student at Tufts University School of Medicine in Boston, MA. stephenson.jessica@gmail.com.
authors.forename: Jessica
authors.initials: J
authors.lastname: Stephenson
authors.affiliation: Public Health Analyst for the Program for Health Care Quality and Outcomes at RTI International. mschwartz@rti.org.
authors.forename: Margot
authors.initials: M
authors.lastname: Schwartz
mesh_terms: D000328:Adult; D001291:Attitude of Health Personnel; D016022:Case-Control Studies; D003071:Cognition; D006801:Humans; D019300:Medical Errors / Q000706:statistics & numerical data*; D008499:Medical Records / Q000706:statistics & numerical data*; D015999:Multivariate Analysis; D012307:Risk Factors; D062606:Tertiary Care Centers / Q000706:statistics & numerical data