Interleukin6 prediction of mortality in critically ill COVID19 patients: A prospective observational cohort study

Abstract

Objective: The aim of this study is to explore the role of IL6 in predicting outcome in critically ill COVID-19 patients. Design Prospective observational cohort study. Setting 20-bed respiratory medical intensive care unit of Abderrahmen Mami Teaching Hospital between September and December 2020.

Methods: We included all critically ill patients diagnosed with COVID-19 managed in ICU. IL6 was measured during the first 24 hours of hospitalization.

Results: 71 patients were included with mean age of 64 ± 12 years, gender ratio of 22. Most patients had comorbidities, including hypertension (n = 32, 45%), obesity (n = 32, 45%) and diabetes (n = 29, 41%). Dexamethasone 6 mg twice a day was initiated as treatment for all patients. Thirty patients (42%) needed high flow oxygenation; 59 (83%) underwent non-invasive ventilation for a median duration 2 [1-5] days. Invasive mechanical ventilation was required in 44 (62%) patients with a median initiation delay of 1 [0-4] days. Median ICU length of stay was 11 [7-17] days and overall mortality was 61%. During the first 24 hours, median IL6 was 34.4 [12.5-106] pg/ml. Multivariate analysis shows that IL-6 ≥ 20 pg/ml, CPK < 107 UI/L, AST < 30 UI/L and invasive ventilation requirement are independent risk factors for mortality.

Conclusions: IL-6 is a strong mortality predictor among critically ill COVID19 patients. Since IL-6 antagonist agents are costly, this finding may help physicians to consider patients who should benefit from that treatment.

Fig 1. Serum IL-6 concentration correlation with age, C-reactive protein, zinc, and D-dimers (r = Spearman’s coefficient).

Fig 2. Receiver operating characteristic (ROC) curve showing the predictive power of IL-6 for predicting ICU mortality among critically ill COVID-19 patients.