title: Derivation and Internal Validation of a Clinical Prediction Tool for 30-Day Mortality in Lower Gastrointestinal Bleeding.
abstract: BACKGROUND
  There are limited data to predict which patients with lower gastrointestinal bleeding are at risk for adverse outcomes. We aimed to develop a clinical tool based on admission variables to predict 30-day mortality in lower gastrointestinal bleeding.
  
  
  METHODS
  We used a validated machine learning algorithm to identify adult patients hospitalized with lower gastrointestinal bleeding at an academic medical center between 2008 and 2015. The cohort was split randomly into derivation and validation cohorts. In the derivation cohort, we used multiple logistic regression on all candidate admission variables to create a prediction model for 30-day mortality, using area under the receiving operator characteristic curve and misclassification rate to estimate prediction accuracy. Regression coefficients were used to derive an integer score, and mortality risk associated with point totals was assessed.
  
  
  RESULTS
  In the derivation cohort (n = 4044), 8 variables were most associated with 30-day mortality: age, dementia, metastatic cancer, chronic kidney disease, chronic pulmonary disease, anticoagulant use, admission hematocrit, and albumin. The model yielded a misclassification rate of 0.06 and area under the curve of 0.81. The integer score ranged from -10 to 26 in the derivation cohort, with a misclassification rate of 0.11 and area under the curve of 0.74. In the validation cohort (n = 2060), the score had an area under the curve of 0.72 with a misclassification rate of 0.12. After dividing the score into 4 quartiles of risk, 30-day mortality in the derivation and validation sets was 3.6% and 4.4% in quartile 1, 4.9% and 7.3% in quartile 2, 9.9% and 9.1% in quartile 3, and 24% and 26% in quartile 4, respectively.
  
  
  CONCLUSIONS
  A clinical tool can be used to predict 30-day mortality in patients hospitalized with lower gastrointestinal bleeding.
authors.affiliation: Section of Gastroenterology, Hepatology, and Nutrition, Department of Medicine, University of Chicago Medical Center, Ill. Electronic address: nsengupta@medicine.bsd.uchicago.edu.
authors.forename: Neil
authors.initials: N
authors.lastname: Sengupta
authors.affiliation: Division of Gastroenterology, Department of Internal Medicine, University of Michigan Health System, Ann Arbor.
authors.forename: Elliot B
authors.initials: EB
authors.lastname: Tapper
mesh_terms: D000368:Aged; D000465:Algorithms; D003113:Colonoscopy; D003661:Decision Support Techniques; D005260:Female; D006471:Gastrointestinal Hemorrhage / Q000209:etiology / Q000401:mortality*; D017052:Hospital Mortality; D006801:Humans; D016015:Logistic Models; D008297:Male; D008875:Middle Aged; D012372:ROC Curve; D015203:Reproducibility of Results; D012307:Risk Factors; D012680:Sensitivity and Specificity
keywords: Lower gastrointestinal bleeding; Mortality