Blood cell differential count discretization methods to predict survival in acutely ill adults reporting to the emergency room: a retrospective cohort study in 2020

Aims To assess survival predictivity of baseline blood cell differential count (BCDC) discretization methods in acutely ill adults visiting the emergency room over one-year. Methods Retrospective cohort study on one-year survival of adults reporting to the emergency room of the A. Manzoni Hospital (Italy) during 2020. Automated BCDC analysis performed at baseline, assessed hemoglobin, red cell mean volume and distribution width (RDW), platelet distribution width (PDW), platelet-hematocrit, absolute red blood cells, white blood cells, neutrophils, lymphocytes, monocytes, eosinophils, basophils, and platelets. Discretization cutoffs were defined by: Benchmark laboratory reference values and Tailored (maximally selected rank statistics for linear and sigmoid-shaped distributed variables; optimal-equal hazard ratio (HR) method for U-shaped distributed variables. Explanatory variables (age, gender, inward admission) were analyzed using Cox multivariable regression. Receiver operating characteristic curves used the sum of Cox-significant variables in each method. Results Of 11052 patients (median age 67 years, interquartile range (IQR) 51–81, 48% female), 59% (n=6489) were discharged and 41% (n=4563) were admitted. After a 306-day median follow up (IQR 208–417 days), 9455 (86%) patients were alive and 1597 (14%) deceased. Increased HRs were associated with age > 73 years (HR=4.29 CI 3.78–4.87), and hospital admission (HR=2.05, CI 1.83–2.29). Age, sex, hemoglobin, mean corpuscular volume, RDW, PDW, neutrophils, lymphocytes and eosinophils were significant in overall. Benchmark included basophils and platelet count (area under the ROC curve (AUROC) 0.78). Tailored included monocyte counts and PCT (AUROC of 0.82). Conclusions Tailored discretization of BCDC provided meaningful insight regarding acute patient survival. What is already known on this topic Information on survival predictivity of BCDC is scarce, particularly in acutely ill patients considering that reference values are based on the general population. What this study adds Laboratory reference interval values predicting survival were hemoglobin, RDW, MCV, neutrophil, lymphocyte, eosinophil, and basophils counts, PLT, and PDW, independently of sex, age, and acute inward admission. Survival predictivity was improved by discretization of hemoglobin, RDW, MCV, neutrophil, lymphocyte, eosinophil, and monocyte counts, and PDW, according to the maximally selected rank statistics and optimal-equal HR method. How this study might affect research, practice, or policy Baseline BCDC discretized by tailored methods may be a useful biomarker for hazard warning in acute illness. ### Competing Interest Statement The authors have declared no competing interest. ### Funding Statement This study did not receive any funding ### Author Declarations I confirm all relevant ethical guidelines have been followed, and any necessary IRB and/or ethics committee approvals have been obtained. Yes The details of the IRB/oversight body that provided approval or exemption for the research described are given below: IRB of ASST Lecco gave ethical approval for this work on 2021-07-14 by deliberation no 566 I confirm that all necessary patient/participant consent has been obtained and the appropriate institutional forms have been archived, and that any patient/participant/sample identifiers included were not known to anyone (e.g., hospital staff, patients or participants themselves) outside the research group so cannot be used to identify individuals. Yes I understand that all clinical trials and any other prospective interventional studies must be registered with an ICMJE-approved registry, such as ClinicalTrials.gov. I confirm that any such study reported in the manuscript has been registered and the trial registration ID is provided (note: if posting a prospective study registered retrospectively, please provide a statement in the trial ID field explaining why the study was not registered in advance). Yes I have followed all appropriate research reporting guidelines and uploaded the relevant EQUATOR Network research reporting checklist(s) and other pertinent material as supplementary files, if applicable. Yes All data produced in the present study are available upon reasonable request to the authors