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Published on: August 19, 2020
Heart rate characteristics predict risk of mortality in preterm infants in low and high target oxygen saturation
William E King1, Urvi Jhaveri Sanghvi2, Namasivayam Ambalavanan3
1Medical Predictive Science Corporation, Charlottesville, VA, USA.
Insights
The heart rate characteristics index (HRCi) accurately predicts mortality risk in preterm infants across different oxygen saturation targets. This finding may help individualize oxygen therapy for vulnerable newborns.
Area of Science:
- Neonatal medicine
- Clinical research
- Biomedical engineering
Background:
- The Neonatal Oxygenation Prospective Meta-analysis revealed that targeting lower oxygen saturation (SpO2) ranges (85-89%) in preterm infants (<28 weeks) reduced retinopathy of prematurity but increased mortality compared to higher ranges (91-95%).
- This highlights a critical trade-off in managing oxygenation in extremely preterm infants and the need for precise risk assessment.
Purpose of the Study:
- To evaluate the accuracy of the heart rate characteristics index (HRCi) in predicting the dynamic risk of mortality in preterm infants.
- To assess HRCi's predictive performance across both low (85-89%) and high (91-95%) target oxygen saturation (SpO2) ranges.
Main Methods:
- Linked data from the SUPPORT and HRCi studies for infants managed within overlapping randomized controlled trial periods.
- Examined the maximum daily HRCi (MaxHRCi24) to predict mortality using predictiveness curves and receiver operating characteristic (ROC) analysis (AUROC) over 1-60 day prediction windows.
- Utilized Cox proportional hazards models and moderation analysis to determine MaxHRCi24's independent predictive value and interaction with SpO2 targets.
Main Results:
- MaxHRCi24 demonstrated strong predictive accuracy for mortality in both lower (AUROC 0.79-0.89) and higher (AUROC 0.82-0.91) SpO2 target groups.
- MaxHRCi24 was identified as a significant independent predictor of mortality when included in multivariable models.
- Moderation analysis indicated that MaxHRCi24 and the target SpO2 range, along with their interaction, were significant predictors of mortality.
Conclusions:
- The heart rate characteristics index (HRCi) effectively predicts mortality risk in preterm infants, irrespective of the targeted oxygen saturation range.
- These findings suggest that HRCi metrics could be valuable for optimizing individualized oxygen saturation targets in hospitalized preterm infants, potentially improving clinical outcomes.
Background:
The Neonatal Oxygenation Prospective Meta-analysis found that in infants <28 weeks gestational age, targeting an oxygen saturation (S pO ) range of 85-89% versus 91-95% resulted in lower rates of retinopathy of prematurity but increased mortality. We aimed to evaluate the accuracy of the heart rate characteristics index (HRCi) in assessing the dynamic risk of mortality among infants managed with low and high target S pO ranges.
Methods:
We linked the SUPPORT and HRCi datasets from one centre in which the randomised controlled trials overlapped. We examined the maximum daily HRCi (MaxHRCi24) to predict mortality among patients randomised to the lower and higher target S pO groups by generating predictiveness curves and calculating model performance metrics, including area under the receiver operating characteristics curve (AUROC) at prediction windows from 1-60 days. Cox proportional hazards models tested whether MaxHRCi24 was an independent predictor of mortality. We also conducted a moderation analysis.
Results:
There were 84 infants in the merged dataset. MaxHRCi24 predicted mortality in infants randomised to the lower target S pO (AUROC of 0.79-0.89 depending upon the prediction window) and higher target S pO (AUROC 0.82-0.91). MaxHRCi24 was an important additional predictor of mortality in multivariable modelling. In moderation analysis, in a model that also included demographic predictor variables, the individual terms and the interaction term between MaxHRCi24 and target S pO range all predicted mortality.
Conclusions:
Associations between HRCi and mortality, at low and high S pO target ranges, suggest that future research may find HRCi metrics helpful to individually optimise target oxygen saturation ranges for hospitalised preterm infants.
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