Evaluating Age-Predicted Maximal Heart Rate Versus Tachycardia in SIRS Criterion

Area of Science:

• Critical Care Medicine
• Cardiology
• Biostatistics

Background:

• Tachycardia (heart rate >90 bpm) is a common but nonspecific criterion in SIRS, limiting its utility for sepsis screening.
• Individualizing tachycardia assessment using age-predicted maximal heart rate (%APMHR) may offer better physiological reserve estimation and mortality risk stratification.

Purpose of the Study:

• To evaluate the efficacy of %APMHR ≥60 as a replacement for the traditional tachycardia criterion (HR >90) in the SIRS criteria for predicting in-hospital mortality.
• To compare the predictive performance of a novel SIRS model (nSIRS) incorporating %APMHR with the traditional SIRS criteria.

Main Methods:

• Retrospective analysis of 62,327 ICU patients from the MIMIC-IV dataset.
• Calculation of %APMHR by dividing patient's heart rate by their age-predicted maximal heart rate (using the Fox formula).
• Multinomial logistic regression used to compare mortality prediction between traditional SIRS and the nSIRS model (%APMHR ≥60).

Main Results:

• %APMHR ≥60 showed similar mortality prediction to HR >90 (16.54% vs 15.06%).
• Higher %APMHR values (≥70) were associated with increased mortality, while lower values (≤50) showed decreased risk.
• The nSIRS model using %APMHR ≥60 demonstrated superior mortality prediction (larger log-likelihood, smaller AIC/BIC) compared to traditional SIRS, with slightly fewer patients meeting nSIRS ≥2 criteria.

Conclusions:

• %APMHR ≥60 is a comparable predictor of in-hospital mortality to the traditional HR >90 criterion.
• The nSIRS model incorporating %APMHR shows improved mortality prediction in ICU patients.
• Tachycardia's mortality risk increases with patient age; further research into incorporating %APMHR into screening tools is warranted.