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International Early Warning System (IEWS)

 

Input
 

Age		mo yr
Sex	Female (0)
	Male (1)
Respiratory Rate		/min br/min breaths/min
O2Sat		% fraction percent rate ratio
Supplemental O2	No (0)
	Yes (1)
Temperature		Cel Degrees C Degrees F degC degF
Systolic Blood Pressure		Pascal cmH2O mm/Hg mmHg mm[Hg] torr
Heart Rate		/min beats/min bpm
AVPU	Alert (0)
	Verbal, pain, or unresponsive (5)

 

Results
 
Important: Inputs must be complete to perform calculation.

 

IEWS Points		# count index logit none number points score [No Unit]
Odds
Hospital Mortality Estimate		% fraction percent rate ratio
Decimal Precision   0 1 2 3

 

Data action

 

     
 
Include literature references: Yes   No

 

 

Notes

• The following notes were submitted by Dr. Bart Candel 5/1/2025.
• The International Early Warning Score (IEWS)^[1] is a recalibrated version of the National Early Warning Score (NEWS), developed to improve age and sex-adjusted in-hospital mortality prediction risk upon arrival at the emergency department (ED). This adjustment incorporates age and sex, addressing limitations in the original NEWS model. The IEWS was developed in the Netherlands and validated in Denmark.
• In the IEWS, points assigned to each vital sign, as well as sex and age, are derived from a statistical model (logistic regression) that estimates the actual association of each variable with in-hospital mortality for ED patients. This is a major improvement over the NEWS, where points are assigned based on distribution and expert opinion rather than outcome-based modeling.
• The IEWS demonstrated superior performance over NEWS in predicting in-hospital mortality, with an area under the receiver operating characteristic curve (AUC) of 0.89 in the development cohort (Netherlands) and 0.87 in the external validation cohort (Denmark), compared to 0.82 for NEWS in both cohorts. The recalibration process led to better alignment between predicted and observed risks, particularly enhancing the accuracy for older patients, who were previously at risk of being underestimated by NEWS, while younger patients were overestimated for mortality.
• Decision curve analysis indicated that the IEWS offers a standardized net benefit of 5–15% across relevant risk thresholds (1–15%), identifying 5–15% more true deaths without increasing false positives compared to NEWS. Using the IEWS will therefore better recognize the patients at risk while reducing ‘false alarms’.
• IEWS Interpretation
  • In general, an IEWS of 10 (mortality risk of 4.8%) or more is considered high risk.
  • However, these thresholds may vary depending on individual factors such as age, comorbidities, and frailty. For instance, a 20-year-old may be considered high risk with a score above 3%, whereas for an 80-year-old, a score above 10% might indicate high risk.
• When integrating the IEWS into clinical practice, it's essential to ensure that all relevant vital signs and demographic information are accurately recorded. Training staff to interpret and respond to the IEWS appropriately is crucial for maximizing its effectiveness in improving patient outcomes. Clinical actions should be combined with certain IEWS value

 
Equations used
 

IEWSPoints = AgeFactor + Sex + RespiratoryRateFactor + O2SatFactor + Supplemental O2 + TemperatureFactor + SystolicBloodPressureFactor + HeartRateFactor + AVPU

Odds = e((0.38412316*IEWSPoints)-6.8147501)

HospitalMortalityEstimate = 100 * Odds / (1 + Odds)

 

 

Calculation Details and Variables

• AgeFactor is assigned values by this ordered logic:
  • If Age ≥91 yr, AgeFactor = 7
  • Else if Age ≥81 yr, AgeFactor = 6
  • Else if Age ≥76 yr, AgeFactor = 5
  • Else if Age ≥66 yr, AgeFactor = 4
  • Else if Age ≥61 yr, AgeFactor = 3
  • Else if Age ≥51 yr, AgeFactor = 2
  • Else if Age ≥41 yr, AgeFactor = 1
  • Else AgeFactor = 0.
• Equation parameters such as Sex, have two or more discrete values that may be used in the calculation. The numbers in the parentheses, e.g. (0), represent the values that will be used.
• RespiratoryRateFactor is assigned values by this ordered logic:
  • If Respiratory Rate ≥25 breaths/min, RespiratoryRateFactor = 3
  • Else if Respiratory Rate ≥21 breaths/min, RespiratoryRateFactor = 2
  • Else RespiratoryRateFactor = 0.
• O2SatFactor is assigned values by this ordered logic:
  • If O₂Sat ≥96 %, O2SatFactor = 0
  • Else if O₂Sat ≥92 %, O2SatFactor = 1
  • Else O2SatFactor = 3.
• TemperatureFactor is assigned values by this ordered logic:
  • If Temperature ≥36.1 degC, TemperatureFactor = 0
  • Else if Temperature ≥35.1 degC, TemperatureFactor = 3
  • Else TemperatureFactor = 5.
• SystolicBloodPressureFactor is assigned values by this ordered logic:
  • If Systolic Blood Pressure ≥220 mmHg, SystolicBloodPressureFactor = 2
  • Else if Systolic Blood Pressure ≥111 mmHg, SystolicBloodPressureFactor = 0
  • Else if Systolic Blood Pressure ≥91 mmHg, SystolicBloodPressureFactor = 1
  • Else SystolicBloodPressureFactor = 2.
• HeartRateFactor is assigned values by this ordered logic:
  • If Heart Rate ≥111 beats/min, HeartRateFactor = 2
  • Else if Heart Rate ≥91 beats/min, HeartRateFactor = 1
  • Else if Heart Rate ≥51 beats/min, HeartRateFactor = 0
  • Else HeartRateFactor = 1.

 

References

1. Candel BGJ, Nissen SK, Nickel CH, et al. Development and External Validation of the International Early Warning Score for Improved Age- and Sex-Adjusted In-Hospital Mortality Prediction in the Emergency Department. Crit Care Med. 2023 Jul 1;51(7):881-891. PubMed ID: 36951452

 

Associated Medical Subject Headings [MeSH]
 

Aged,   Cohort Studies,   Early Warning Score,   Emergency Service,   Hospital,   Hospital Mortality,   Humans,   ROC Curve,   Vital Signs

 

Associated Logical Observation Identifiers Names and Codes [LOINC]
 

Parameter	LOINC's and Suggested Units
Age	21612-7 : yr      21612-7 : yr      21612-7 : years      30525-0 : Years old      30525-0 : yr      30525-0 : years
Respiratory Rate	9303-9 : breaths/min      9279-1 : breaths/min      76170-0 : breaths/min      19840-8 : breaths/min
O2Sat	2708-6 : %      2713-6 : %      51733-4 : %      59408-5 : %
Temperature	8329-5 : degC      8310-5 : degC      8331-1 : degC      8332-9 : degC      8333-7 : degC      8328-7 : degC      75539-7 : degC
Systolic Blood Pressure	8480-6 : mmHg
Heart Rate	8867-4 : beats/min      8893-0 : beats/min      8890-6 : beats/min      8889-8 : beats/min      68999-2 : beats/min      76282-3 : beats/min      69000-8 : beats/min      69001-6 : beats/min

 
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