Trimethylamine N-oxide as a potential prognostic biomarker for mortality in patients with COVID-19 disease

Trimethylamine N-oxide (TMAO) is suggested as a biomarker for inflammatory and cardiovascular diseases which are identified as risk factors for severe cases of coronavirus disease 2019 (COVID-19). Our primary aim was to assess prognostic potential of serum TMAO levels in predicting COVID-19-related mortality. The secondary aim was to examine the potential of various biochemical parameters, particularly those associated with inflammation or thrombosis, as predictors of mortality.

In this prospective and single-centre study, COVID-19 patients were categorized as death (group 1) or discharged (group 2) based on their in-hospital mortality status. The characteristics of participants were documented, and clinical data, including TMAO, angiotensin-converting enzyme-2 (ACE2), and neutrophil to lymphocyte ratio (NLR), were determined. The association of these independent variables with the COVID-19-related mortality, was assessed by calculation of crude odds ratios (OR) in bivariate and logistic regression analysis. Receiver operation characteristic (ROC) analysis was used for cut-off values.

The serum levels of TMAO, ACE2 and NLR were markedly higher in group 1 on the days of hospital admission (p ​< ​0.05, p ​< ​0.05, and p ​< ​0.01, respectively). Serum TMAO levels (OR 1.422; 95 ​% CI [1.067-1.894]; p ​= ​0.016) and NLR (OR 1.166; 95 ​% CI [1.012-1.343]; p ​= ​0.033) were determined as independent predictors for COVID-19-related mortality with after multivariate logistic regression analysis. The optimal cut-off values were detected as 7.9 ​ng/ml for TMAO (71 ​% sensitivity, 68 ​% specificity, AUC ​= ​0.701).

The findings of this initial study indicate that serum TMAO levels and NLR may be useful in predicting mortality in the early stages of COVID-19.