Modified HScore Predicts Increased Length of Stay but not Mortality in ICU Patients with COVID-19- A Retrospective Cohort Study

Abstract

Hemophagocytic Lymphohistiocytosis (HLH) is an acute and rapidly progressive systemic inflammatory disorder that can be classified into primary HLH (pHLH), which is a pediatric disease, and secondary HLH (sHLH), which can be associated with infection, malignancy, systemic diseases or drugs [1 ]. The disease is characterized by cytopenia, excessive cytokine production, and hyperferritinemia, and clinically presents with ongoing fevers, lymphadenopathy, hepatosplenomegaly, and multiorgan failure. Of these characteristics, impaired cytotoxic cell function is perhaps the most important and leads to massive cytokine release and a cytokine storm [2 ]. In 2014 Fardet, et al. developed the HScore which combines physical exam findings and laboratory values to aid in the diagnosis of HLH with a 93% sensitivity and 86% specificity [ 2 , 3]. Viral infections are the predominant cause of sHLH, with the most recent inclusion of severe acute respiratory syndrome from coronavirus 2 (SARS-CoV-2), or COVID-19. Overall hospital mortality from COVID-19 early on in the disease was reported to be approximately 15-20%, with up to 40% of patients requiring ICU admission whereas more recent mortality numbers range from 10-20% [ 4 , 5 ]. The wider range can be attributed to proportionally more younger patients being affected later in the course, additional experience over time and the widespread use of therapies such as prone positioning, steroids and immune modulators. While an association between elevated HScore and adverse outcomes in COVID-19 patients has been proposed, its utility as a risk-stratification tool has not been established in patients with COVID-19 [ 6]. We therefore undertook this study to investigate whether HScore within the first 24 hours of admission can be used as a prognostic tool to predict outcomes of critically ill adults with COVID-19. We hypothesized that a higher score may be associated with higher mortality.