title: Customized reference ranges for laboratory values decrease false positive alerts in intensive care unit patients.
abstract: BACKGROUND
  Traditional electronic medical record (EMR) interfaces mark laboratory tests as abnormal based on standard reference ranges derived from healthy, middle-aged adults. This yields many false positive alerts with subsequent alert-fatigue when applied to complex populations like hospitalized, critically ill patients. Novel EMR interfaces using adjusted reference ranges customized for specific patient populations may ameliorate this problem.
  
  
  OBJECTIVE
  To compare accuracy of abnormal laboratory value indicators in a novel vs traditional EMR interface.
  
  
  METHODS
  Laboratory data from intensive care unit (ICU) patients consecutively admitted during a two-day period were recorded. For each patient, available laboratory results and the problem list were sent to two mutually blinded critical care experts, who marked the values about which they would like to be alerted. All disagreements were resolved by an independent super-reviewer. Based on this gold standard, we calculated and compared the sensitivity, specificity, positive and negative predictive values (PPV, NPV) of customized vs traditional abnormal value indicators.
  
  
  RESULTS
  Thirty seven patients with a total of 1341 laboratory results were included. Experts' agreement was fair (kappa = 0.39). Compared to the traditional EMR, custom abnormal laboratory value indicators had similar sensitivity (77% vs 85%, P = 0.22) and NPV (97.1% vs 98.6%, P = 0.06) but higher specificity (79% vs 61%, P < 0.001) and PPV (28% vs 11%, P < 0.001).
  
  
  CONCLUSIONS
  Reference ranges for laboratory values customized for an ICU population decrease false positive alerts. Disagreement among clinicians about which laboratory values should be indicated as abnormal limits the development of customized reference ranges.
authors.affiliation: Multidisciplinary Epidemiology and Translational Research in intensive care, emergency and perioperative Medicine (METRIC), Division of Pulmonary and Critical Care Medicine, Department of Medicine, Mayo Clinic, Rochester, Minnesota, United States of America.
authors.forename: Oguz
authors.initials: O
authors.lastname: Kilickaya
authors.affiliation: Multidisciplinary Epidemiology and Translational Research in intensive care, emergency and perioperative Medicine (METRIC), Division of Pulmonary and Critical Care Medicine, Department of Medicine, Mayo Clinic, Rochester, Minnesota, United States of America; University Witten-Herdecke, Witten, Germany.
authors.forename: Christopher
authors.initials: C
authors.lastname: Schmickl
authors.affiliation: Multidisciplinary Epidemiology and Translational Research in intensive care, emergency and perioperative Medicine (METRIC), Division of Pulmonary and Critical Care Medicine, Department of Medicine, Mayo Clinic, Rochester, Minnesota, United States of America.
authors.forename: Adil
authors.initials: A
authors.lastname: Ahmed
authors.affiliation: Multidisciplinary Epidemiology and Translational Research in intensive care, emergency and perioperative Medicine (METRIC), Division of Pulmonary and Critical Care Medicine, Department of Medicine, Mayo Clinic, Rochester, Minnesota, United States of America; Division of Critical Care, Department of Anesthesiology, Mayo Clinic, Rochester, Minnesota, United States of America.
authors.forename: Juan
authors.initials: J
authors.lastname: Pulido
authors.affiliation: Multidisciplinary Epidemiology and Translational Research in intensive care, emergency and perioperative Medicine (METRIC), Division of Pulmonary and Critical Care Medicine, Department of Medicine, Mayo Clinic, Rochester, Minnesota, United States of America; Division of Critical Care, Department of Anesthesiology, Mayo Clinic, Rochester, Minnesota, United States of America.
authors.forename: James
authors.initials: J
authors.lastname: Onigkeit
authors.affiliation: Division of Pulmonary and Critical Care, Department of Medicine, Mayo Clinic, Rochester, Minnesota, United States of America; Division of Nephrology and Hypertension, Department of Medicine, Mayo Clinic, Rochester, Minnesota, United States of America.
authors.forename: Kianoush
authors.initials: K
authors.lastname: Kashani
authors.affiliation: Multidisciplinary Epidemiology and Translational Research in intensive care, emergency and perioperative Medicine (METRIC), Division of Pulmonary and Critical Care Medicine, Department of Medicine, Mayo Clinic, Rochester, Minnesota, United States of America; Division of Critical Care, Department of Anesthesiology, Mayo Clinic, Rochester, Minnesota, United States of America.
authors.forename: Ognjen
authors.initials: O
authors.lastname: Gajic
authors.affiliation: Multidisciplinary Epidemiology and Translational Research in intensive care, emergency and perioperative Medicine (METRIC), Division of Pulmonary and Critical Care Medicine, Department of Medicine, Mayo Clinic, Rochester, Minnesota, United States of America; Division of Critical Care, Department of Anesthesiology, Mayo Clinic, Rochester, Minnesota, United States of America.
authors.forename: Vitaly
authors.initials: V
authors.lastname: Herasevich
authors.affiliation: Multidisciplinary Epidemiology and Translational Research in intensive care, emergency and perioperative Medicine (METRIC), Division of Pulmonary and Critical Care Medicine, Department of Medicine, Mayo Clinic, Rochester, Minnesota, United States of America; Division of Critical Care, Department of Anesthesiology, Mayo Clinic, Rochester, Minnesota, United States of America.
authors.forename: Brian
authors.initials: B
authors.lastname: Pickering
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D019963:Clinical Chemistry Tests / Q000592:standards; D003422:Critical Care; D016638:Critical Illness; D057286:Electronic Health Records; D005189:False Positive Reactions; D005260:Female; D017052:Hospital Mortality; D006801:Humans; D007362:Intensive Care Units; D008297:Male; D008875:Middle Aged; D012016:Reference Values; D012680:Sensitivity and Specificity