Impact of Lymphopenia on COVID-19 infection Severity Single-center experience

Abstract

The World Health Organization (WHO) has declared Coronavirus disease 2019 (COVID-19) as a global public health pandemic. Prudent allocation of resources in a pandemic is essential, and therefore clinical and laboratory biomarkers should be utilized to predict the severity of COVID-19 and allow for resources to be distributed appropriately. A retrospective study was conducted to investigate the association of lymphocyte count with admission rate and disease severity at University Hospital Waterford (UHW) and affiliated sector hospitals. A total of 22,213 samples were received at our Laboratory for COVID-19 testing by PCR. A quarter of the samples (185 cases) were received from COVID-19 Emergency Department pathways at our hospitals. Six per cent of the PCR positive patients were only mildly symptomatic and discharged from ED without blood testing. Overall, 150 (20%) patients were required hospital admission due to disease severity. Of these, 11 (1.4%) patients were admitted to ICU. The mortality rate in this cohort was 4.2% (35 patients), and 29 of these were aged over 60 years. The analysis showed that patients with poor outcomes had lower lymphocyte counts. The median lymphocyte counts for ICU and RIP cohorts were 0.81 x10 9 /L (range 0.42-1.66) and 0.68 x 10 9 /L (0.21-2.2) respectively. Our study showed rates of COVID-19 infection and hospital admissions that are comparable with the reported literature. The impact of lymphopenia on disease severity and mortality is most significant in elderly populations. Therefore, older age and lymphopenia may be used in combination to predict poor progno sis in COVID-19 patients.