Laboratory parameters related to severe disease and death in SARS-CoV-2 pneumonia: Retrospective analysis

Abstract

The clinical evolution of coronavirus disease 2019 (COVID-19) is highly variable and hospitalized patients can rapidly develop conditions requiring oxygen support, intensive care unit (ICU) or high dependency unit (HDU) care. Early identification of high-risk patients is mandatory. We retrospectively collected the medical history, symptoms, radiological, and laboratory findings of COVID-19 patients hospitalized between February and April 2020. Laboratory data were collected at the first, last, and middle times of hospitalization. We used arterial oxygen partial pressure and fractional inspired oxygen ratio (P/F) to evaluate respiratory status. Outcomes considered were death and ICU/HDU admission. We used the χ² or Fisher's exact test to examine differences between categorical variables. Continuous variables were analyzed using the Wilcoxon matched pairs signed-ranks test and Mann-Whitney test sample test. Of 71 patients admitted, 92% had interstitial pneumonia, and 17% an unfavorable outcome. Negative predictors were age, cerebrovascular disease, obesity, and chronic obstructive pulmonary disease. Baseline P/F was strongly associated with all outcomes. Markers linked to immunological dysregulation like elevated neutrophil-to-lymphocyte ratio exhibited prognostic significance over time. A validated prognostic score comprehensive of all these conditions for early staging and management of COVID-19 patients is urgently needed. Further studies are desirable to evaluate whether laboratory tests can target early treatment in high-risk patients.

Keywords: laboratory parameters; neutrophil-to-lymphocyte ratio; prognostic factors; severe COVID-19.