# U-shaped association between hemoglobin to red blood cell distribution width ratio and all-cause mortality among critically ill pediatric patients

## TL;DR

This study finds a U-shaped link between a blood ratio and mortality in critically ill children, with the lowest risk at a ratio of 8.91.

## Contribution

The study is the first to identify a U-shaped association between HRR and mortality in critically ill pediatric patients.

## Key findings

- A U-shaped relationship was found between HRR and 28-day in-hospital mortality in critically ill children.
- The lowest mortality risk occurred at an HRR threshold of approximately 8.91.
- Sensitivity analyses confirmed the stability of the observed association.

## Abstract

The lower hemoglobin to red blood cell distribution width ratio (HRR) is associated with an increased risk of mortality in adult patients, but its relationship with clinical progress in the Pediatric Intensive Care Unit (PICU) is unclear. The authors aimed to investigate the association between HRR and all-cause mortality among pediatric patients.

The authors conducted a retrospective cohort study by analyzing the PIC database from 2010 to 2018.HRR was calculated based on laboratory tests conducted within the first 24 hours of PICU admission. The primary outcome was 28-day in-hospital all-cause mortality. Multivariable logistic regression models, restricted cubic spline, and threshold effects analysis were applied to assess the relationship between HRR and mortality in this cohort.

A total of 8015 patients with an average age of the participants was1.5 (0.4, 4.8) years, and 3547 (44.3%) individuals were female. The 28-day in-hospital all-cause mortality was 4.1% (330/8015). The relationship between HRR and mortality was U-shaped, which had a threshold of around 8.91. The effect size on the left and right sides of the inflection point, was 0.803 (95% CI 0.742-0.869, p < 0.001) and 1.421 (95% CI 1.159-1.743, p < 0.001), respectively. No significant interactions were observed between HRR and all-cause mortality, except in patients with high lactate (p for interaction > 0.05). The results of the sensitivity analysis remained stable.

There is a U-shaped relationship between HRR and 28-day in-hospital all-cause mortality in critically ill pediatric. With a lower mortality risk at an HRR of 8.91.