Inflammatory Biomarkers as Predictors of Mortality and Persistent Symptoms at Follow-up in Patients with Severe COVID-19 (preprint)

ABSTRACT

Background: Serum inflammatory biomarkers such as C-reactive protein (CRP) are an established tool for predicting mortality in COVID-19 patients. Data have also suggested that such biomarkers are persistently elevated in patients with Long-COVID. In this study we aimed to assess the relationship between a panel of serum biomarkers (CRP, IL-6, troponin-T, and ferritin), inpatient mortality, and persistent symptoms post-discharge in COVID-19 survivors. Methods: Data were collected retrospectively for all patients with COVID-19 admitted between 1st September 2020 and 10th January 2021. Admission CRP, IL-6, ferritin, and troponin-T were collected alongside routinely collected clinical data. A standardised dataset was collected for survivors when they attended clinical follow-up with the local post-hospitalisation COVID-19 follow-up service. Results: A total of 626 patients (mean age 70.1 [SD=15.8], 55% male) had all biomarkers recorded. The overall mortality rate in this cohort was 28.4%. Higher levels of IL-6 (p<0.001) and troponin-T (p<0.001) were associated with a significantly higher risk of inpatient mortality. A total of 144 patients received 3-month follow-up, the commonest reported symptoms were fatigue (54.2%), breathlessness (52.8%), and sleep disturbance (37.5%). Patients who reported myalgia, low mood, and anxiety were found to have lower median levels of IL-6, CRP, and ferritin, respectively. Conclusions: Raised levels of IL-6 and TT on admission are associated with a significantly increased risk of inpatient mortality in those hospitalised with COVID-19, however, raised inflammatory markers at the time of hospital admission show no association with residual symptom burden at 3-month follow-up in surviving patients.