Factors Associated with Hospital Admission Decisions in Hematologic Emergency Department Patients: A Hierarchical...

Background and Objectives: To identify factors associated with hospital admission decisions among hematologic patients presenting to the emergency department (ED) and to evaluate the incremental contribution of clinical, laboratory, and process-related variables using a hierarchical modeling framework. Materials and Methods: Single-center, retrospective observational cohort study conducted between January 2016 and December 2018. Adult patients for whom a hematology consultation was requested at ED presentation were included. Hierarchical block modeling was used as a sequential multivariable logistic regression approach in which clinical, laboratory, and process-related variables were entered in separate blocks. Process-related variables were defined as ED workflow-related factors, including mode of arrival, timing of presentation, and transfusion requirement. Model performance was assessed using the area under the receiver operating characteristic curve (AUC), Hosmer-Lemeshow goodness-of-fit test, calibration plot, calibration slope/intercept, and nested bootstrap internal validation. Results: Of 428 patients included, 297 (69.4%) were hospitalized. In the updated final model, impaired mental status (aOR 2.682; 95% CI 1.393-5.161), ambulance arrival (aOR 2.607; 95% CI 1.532-4.434), body temperature (aOR 1.399 per °C; 95% CI 1.049-1.866), respiratory rate (aOR 1.105 per breath/min; 95% CI 1.019-1.197), and heart rate (aOR 1.023 per bpm; 95% CI 1.007-1.040) were independently associated with hospital admission. Transfusion requirement showed an inverse association with admission (aOR 0.397; 95% CI 0.244-0.644), whereas platelet count showed the same direction of association but did not reach statistical significance in the updated final model. The final model demonstrated moderate apparent discrimination (AUC 0.771; 95% CI 0.725-0.818), with no statistically significant lack of fit on the Hosmer-Lemeshow test (p = 0.188). After nested bootstrap internal validation, the optimism-corrected AUC was 0.729. Conclusions: In hematologic patients presenting to the ED, admission decisions were associated mainly with acute physiological instability-particularly impaired mental status and abnormal vital signs-rather than by age or sex. These findings should be interpreted as exploratory associations with real-world disposition decisions, not as a validated tool for predicting objective outcomes such as mortality, ICU transfer, or 30-day adverse events.