Prognostic value of biochemical parameters among severe COVID-19 patients admitted to an intensive care unit of a tertiary hospital in South Africa

Abstract

Background: Data on biochemical markers and their association with mortality rates in patients with severe coronavirus disease 2019 (COVID-19) admitted to intensive care units (ICUs) in sub-Saharan Africa are scarce. An evaluation of baseline routine biochemical parameters was performed in COVID-19 patients admitted to the ICU, in order to identify prognostic biomarkers.

Methods: Demographic, clinical, and laboratory data were collected prospectively from patients with PCR-confirmed COVID-19 admitted to the adult ICU of a tertiary hospital in Cape Town, South Africa, between October 2020 and February 2021. Robust Poisson regression methods and the receiver operating characteristic (ROC) curve were used to explore the association of biochemical parameters with severity and mortality.

Results: A total of 82 patients (median age 53.8 years, interquartile range 46.4-59.7 years) were enrolled, of whom 55 (67%) were female and 27 (33%) were male. The median duration of ICU stay was 10 days (interquartile range 5-14 days); 54/82 patients died (66% case fatality rate). Baseline lactate dehydrogenase (LDH) (adjusted relative risk 1.002, 95% confidence interval 1.0004-1.004; P = 0.016) and N-terminal pro B-type natriuretic peptide (NT-proBNP) (adjusted relative risk 1.0004, 95% confidence interval 1.0001-1.0007; P = 0.014) were both found to be independent risk factors of a poor prognosis, with optimal cut-off values of 449.5 U/l (sensitivity 100%, specificity 43%) and 551 pg/ml (sensitivity 49%, specificity 86%), respectively.

Conclusions: LDH and NT-proBNP appear to be promising predictors of a poor prognosis in COVID-19 patients in the ICU. Studies with a larger sample size are required to confirm the validity of this combination of biomarkers.

Keywords: ACE, angiotensin-converting enzyme; ALT, alanine aminotransferase; ARDS, acute respiratory distress syndrome; AST, aspartate aminotransferase; AUC, area under the curve; Biochemical parameters; Biomarkers; CKD-EPI, Chronic Kidney Disease Epidemiology Collaboration; COVID-19; COVID-19, coronavirus disease 2019; CRP, C-reactive protein; HbA1c, haemoglobin A1c; ICU; ICU, intensive care unit; IL, interleukin; IQR, interquartile range; K+, potassium; KDIGO, Kidney Disease Improving Global Outcomes; LDH, lactate dehydrogenase; NHLS, National Health Laboratory Service; NT-proBNP, N-terminal pro B-type natriuretic peptide; Na+, sodium; PCR, polymerase chain reaction; PCT, procalcitonin; Prognostic; ROC, receiver operating characteristic; SARS-CoV-2, severe acute respiratory syndrome coronavirus 2; TnT, troponin T; eGFR, estimated glomerular filtration rate; hs-TnT, high-sensitivity troponin T.

Figure 1

ROC curve of the predictor effect of combined LDH (lactate dehydrogenase) and NT-proBNP (N-terminal pro B-type natriuretic peptide) for a poor prognosis.