Blood cell differential count discretization methods to predict survival in acutely ill adults reporting to the emergency room: a retrospective cohort study in 2020
Authors: Fumagalli Riccardo M. , Chiarelli Marco , Zago Mauro P. , Cazzaniga Massimo , D’angelo Luciano , Cerino Mario , Terragni Sabina , Lainu Elisa , Lorini Cristina , Scarazzati Claudio , Tazzari Sara , Porro Francesca , Aldé Simone , Burati Morena , Brambilla William , Valsecchi Daria , Spreafico Paolo , Tantardini Valter , Schiavo Gianpaolo , Bonato Claudio , Cavalieri d’oro Luca , Nattino Stefano , Locatelli Matteo , Fumagalli Luca A. M. 
Published: January 2023

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.

Key messages

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.