Admission NT-proBNP and outcomes in critically ill COVID-19 patients
Authors: Lopes V , Baptista J P , Moreira N , Goncalves L 
Published: May 2022

Abstract

Funding Acknowledgements
Type of funding sources: None.

Background/Introduction
The association between NT-proBNP levels and prognosis in critically ill non-COVID-19 patients and non-critically ill patients has been studied, but few studies reflect the reality of critically ill COVID-19 patients admitted to a general intensive care unit (ICU).

Purpose
This study sought to investigate the relationship between NT-proBNP levels in COVID-19 patients admitted to an ICU and prognosis.

Methods
We retrospectively analyzed patients consecutively admitted to an ICU with COVID-19, with a median follow-up of 10 months.
Patients who either died or were discharged in the first 48 hours of admission, and who did not have a NT-proBNP measurement in the first 48 hours, were excluded.
Three groups were identified, based on ESC-endorsed, age-specific criteria for classification of NT-proBNP during acute presentations to categorize admission NT-proBNP levels into the following: (1) low (&lt;300 pg/mL); (2) borderline (300–450 ng/mL for ages &lt; 50; 300–900 ng/mL for ages 50–75; and 300–1800 ng/mL for ages &gt; 75,); and (3) high (&gt;450 ng/mL for ages &lt; 50; &gt;900 ng/mL for ages 50–75; and &gt;1800 ng/mL for ages &gt; 75).
Groups were compared, with special interest regarding ICU mortality, duration of mechanical ventilation, length of hospitalization, and in-hospital diagnosis of heart failure. Global mortality (in-hospital and during follow up), and re-hospitalization were also compared. To compare survival, a Kaplan-Meier and multivariate Cox regression analysis were performed.

Results
From a total of 219 patients, 72 (32.8%) had NT-proBNP on admission and were included in the analysis. Mean age was 64.9 ±10.3, 72.2% were male, and median NT-proBNP was 249 (IQR = 1161) pg/mL.
Using age-specific criteria, 37 patients (51.4%) had low, 18 (25.0%) borderline, and 17 (23.6%) high NT-proBNP on admission. Mortality was 34.7%, 37.5%, and 58.8% for patients with low, borderline, and high NT-proBNP, respectively.
Global mortality, re-hospitalization rate, ICU length of stay and duration of mechanical ventilation were similar among groups.
In univariate analysis, patients with high NT-proBNP levels were at significantly higher risk for in-hospital mortality [(HR) 3.60, 95% CI 1.36–9.55, p = 0.010]; in patients with low and borderline levels mortality was not different. In multivariate Cox regression, after adjusting for significant confounders, patients with high NT-proBNP levels remained at significantly higher risk for in-hospital mortality [(HR) 3.44, 95% CI 1.07–10.1, p = 0.039] compared with the lower NT-proBNP groups. No significant differences were found between groups with low and borderline NT-proBNP. Kaplan-Meier survival curves are presented in figure 1.

Conclusion(s)
In critically ill patients with COVID-19, high admission NT-proBNP is associated with higher ICU mortality. Preventive strategies may be required for these patients. Studies with a larger population are required to draw further conclusions.