The role of eosinophil as a diagnostic, differential, and prognostic marker for Covid‐19 during pregnancy: Case–control study from tertiary center

Abstract

Purpose To evaluate the level of eosinophil count in Covid‐19 pregnant patients as a cost‐effective tool for aiding in diagnosis, differential diagnosis, and prognosis and, to assess whether eosinopenia could be similar or superior to lymphopenia in pregnancy with Covid‐19. Methods Retrospective case–control study was conducted including pregnant women tested simultaneously for SARS‐CoV‐2 by RT‐PCR and complete blood count (CBC). Eosinophil counts (EOS), lymphocytes (LYM), neutrophils (NEU) with calculation of EOS/LYM ratio, EOS/NEU ratio, NEU/LYM ratio, LYM/NEU ratio (LNR), eosinopenia, and lymphopenia were compared between the groups. ROC analysis was performed for determination of optimal cut‐off values and comparative analysis between AUC were performed using the paired sample design. Logistic regression was used to determine the factors affecting the categorical variables. Results Four thousand two hundred sixteen pregnant women were included in the final analysis of which (n = 845) as healthy control group, (n = 1482) as non Covid‐19 patient group and (n = 1889) as Covid‐19 group. Covid‐19 group was divided into three subgroups based on severity. To diagnose and distinguish Covid‐19 from other infectious conditions, EOS had better performance with higher area under curve (AUC) (0.769 and 0.757 AUC, respectively, p < 0.001). Categorically, eosinopenia had better diagnostic (Covid‐19 vs. healthy), prognostic (severe–critical vs. mild–moderate), and differential diagnostic (Covid‐19 vs. non Covid‐19) performance than lymphopenia (OR = 5.5 vs. 3.4, OR = 3.4 vs. 1.8, OR = 5.4 vs. 2.7 p = 0.000). Conclusion Eosinopenia is a low‐cost, reliable, and convenient marker for Covid‐19 not only in diagnosis, but also in prognosis by acting as an early marker for predicting severe–critical cases.