The prognostic significance of absolute lymphocyte count in patients with COVID-19

ABSTRACT

INTRODUCTION: The host immune responses try to confront Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) with all the potential cells and cytokines. Eventually, natural killer cells and T cells become exhausted, decreasing their counts, leading to lymphopenia. This study aims to assess the clinical utility of the absolute lymphocyte count (ALC) at admission in predicting outcome in patients with COVID-19. METHODS: Ours was a single-center, retrospective observational study, which included 463 nasopharyngeal swabs SARS-CoV-2 RT-PCR positive patients. Absolute lymphocyte count was retrieved from the admission complete blood count & was divided into 3 sub-groups (<500, <1000, and >1000 cells/μL). Demographics, comorbid conditions, and outcomes such as the need for mechanical ventilation, length of stay, and inpatient mortality were assessed. Statistics were performed using STATA. Significance was assigned at p<0.05. RESULTS: 13.82% of patients had ALC count<500, 44.71% had <1000 and 41.25% had more than 1000. Mean age in ALC group<500 was higher (71±1 years vs 65± 1.1 years in ALC group <1000 and 59.9+/-1.3 in ALC group >1000). Profound lymphopenia (<500 cells/μL) was more common in males compared to females (71.88 % vs 28% p value 0.01). ALC count <500, was associated with higher rate of non-invasive (45.31% vs 26.56% for ALC <1000, p-value 0.01) as well as invasive ventilation (26.5% with ALC <500 vs 19% with ALC <1000 vs 10.4% with ALC with >1000;p-value 0.01). Inpatient mortality was significantly higher in cohort with ALC <500 (51.56% with ALC <500 vs 33.3% with ALC <1000 vs 24.08% with ALC >1000;p-value 0.05). On multivariate regression, ALC was not a independent predictor of mortality (ALC<500, OR 1.56±0.75, p-value 0.44). CONCLUSIONS: Lymphopenia at admission in COVID19 patients is associated with an increased need for non-invasive & invasive ventilation & inpatient mortality. Currently, clinical trials assessing GM-CSF as a possible therapeutic option is underway.