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Higher RAR linked to increased in-hospital mortality in infants with congenital heart diseaseA simple blood ratio may flag higher death risk in heart surgery babies

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Key Takeaway
Consider RAR as a potential prognostic indicator for in-hospital mortality in infants with congenital heart disease, but note the association is not causal.

This was a retrospective, observational cohort study conducted at Guangdong Provincial People’s Hospital. The population included 3634 infants admitted for cardiac surgery between January 2017 and October 2021. The exposure was the red cell distribution width-to-albumin ratio (RAR), with a comparator of RAR ≤ 1.35 fL/(g/L). The primary outcome was in-hospital mortality.

Infants with RAR > 1.35 fL/(g/L) had a significantly higher mortality risk compared to those with RAR ≤ 1.35 fL/(g/L), with an odds ratio (OR) of 2.16 (95% CI 1.01-4.60, p < 0.05). The absolute numbers for mortality were not reported.

Safety and tolerability data were not reported for this blood-based biomarker. The study was limited by its retrospective, single-center design, which restricts generalizability. The authors note the association is not causation.

In clinical practice, RAR demonstrates potential value as an easily measurable blood-based indicator for risk stratification in this population. However, the findings require validation in prospective, multicenter studies before broader application.

For babies born with heart defects, surgery can be lifesaving but still carries real risks. Doctors at one hospital looked at a simple blood test measure called the red cell distribution width-to-albumin ratio, or RAR, to see if it could help identify infants more likely to die during their hospital stay.

They reviewed records for 3,634 infants who had heart surgery between 2017 and 2021. The key finding was that a higher RAR (above 1.35) was linked to roughly double the odds of in-hospital death compared to a lower ratio. This was based on an odds ratio of 2.16, with a 95% confidence interval of 1.01 to 4.60 and a p-value less than 0.05. The study did not report specific numbers of deaths or other detailed outcomes.

This was a retrospective look at patients from a single hospital, so we can’t say the ratio causes worse outcomes, only that it’s associated with them. It also doesn’t tell us whether changing the ratio would improve survival. Still, RAR is easy to get from routine blood work, which makes it a practical tool worth exploring further in broader groups of infants.

What this means for you:
A higher blood ratio was linked to more deaths after infant heart surgery, but it’s an association, not a cause.

Study Details

Study typeCohort
EvidenceLevel 3
PublishedApr 2026
View Original Abstract ↓
In-hospital mortality remains a significant concern in infant cardiac surgery, yet precise risk stratification tools are lacking. The prognostic value of the red cell distribution width-to-albumin ratio (RAR)—a composite marker of inflammation and nutritional status—remains unestablished in this population. This study aimed to examine the association between RAR and in-hospital mortality in infants undergoing cardiac surgery. This work constitutes a retrospective observational cohort analysis. The study population comprised infants admitted to Guangdong Provincial People’s Hospital for cardiac surgery from January 2017 through October 2021.The optimal cut-off value for the RAR was determined to be 1.35 fL/(g/L) using the Youden index method. Based on this threshold, all participants were categorized into a high-RAR group and a low-RAR group. The relationship between RAR levels and mortality during hospitalization was then examined through multiple analytical approaches, including logistic regression, subgroup analyses, and modeling with restricted cubic splines (RCS).The predictive performance of the RAR was further evaluated through an analysis of the receiver operating characteristic (ROC) curve. Mortality rates in this surgical cohort increased with higher RAR values. A consistent relationship linking the RAR to mortality was observed regardless of whether this biomarker was incorporated into statistical models as a continuous measure or a categorical parameter. Among 3634 patients, logistic regression analysis indicated that infants with RAR > 1.35 fL/(g/L) had a significantly higher mortality risk compared to those with RAR ≤ 1.35 fL/(g/L) (OR = 2.16, 95% CI 1.01-4.60, p < 0.05). Furthermore, the direction of the association was consistent across subgroups. The predictive performance of the model was good, with an area under the ROC curve of 0.8. A higher RAR—specifically a value above 1.35 fL/(g/L)—was associated with increased mortality risk during hospitalization in infants undergoing cardiac surgery. As an easily measurable blood-based indicator, RAR demonstrates potential value for clinical practice and research applications.
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