Validation of a Clinical Prediction Rule for Severe Acute Lower Intestinal Bleeding

Abstract

Acute lower intestinal bleeding is a heterogeneous disorder and identification of high-risk patients is challenging. We previously retrospectively identified predictors of severity in patients with acute lower intestinal bleeding. The aim of this study was to prospectively validate a clinical prediction rule for severe acute lower intestinal bleeding. This was a prospective, observational cohort study of consecutive patients admitted to an academic, tertiary care or a community-based teaching hospital for management of acute lower intestinal bleeding. Data were collected on seven previously identified predictors of severe bleeding: heart rate ≥ 100/min, systolic blood pressure ≤ 115 mmHg, syncope, nontender abdominal exam, rectal bleeding in the first 4 h of evaluation, aspirin use, and >2 comorbid conditions. Severe bleeding was defined as transfusion of ≥2 units of red blood cells, and/or a decrease in hematocrit of ≥20% in the first 24 h, and/or recurrent rectal bleeding after 24 h of stability (accompanied by a further decrease in hematocrit of ≥20%, and/or additional blood transfusions, and/or readmission for acute lower intestinal bleeding within 1 wk of discharge). Patients were stratified into 3 risk groups according to the previously developed prediction rule: low (no risk factors), moderate (1–3 risk factors), and high (>3 risk factors). A total of 275 patients with acute lower intestinal bleeding were identified. The risk of severe bleeding in each risk category was similar in the validation and derivation cohorts (p values >0.05): low risk 6% versus 9%, moderate risk 43% versus 43%, and high risk 79% versus 84%. The area under the receiver operating characteristic curve was 0.754 for the validation cohort and 0.761 for the derivation cohort. The magnitude of the risk score was significantly correlated with major clinical outcomes including surgery, death, blood transfusions, and length of stay. We have developed and prospectively validated a clinical prediction rule for acute severe lower intestinal bleeding. This prediction rule could improve the triage of patients to appropriate levels of care and interventions, and guide a more standardized approach to acute lower intestinal bleeding.