EBMcalc Medical Calculator

COVID-19 ISARIC C4 Score

Input

Age

Sex Female (0) Male (1)

Comorbidities

Respiratory Rate

O₂Sat

Glasgow Coma Scale

BUN

CRP

Result

Important: Inputs must be complete to perform calculation.

C4 Score

C4 Score and In-hospital Mortality Prediction

0 to 3 points:

Low risk (1.2 to1.7% mortality)

4 to 8 points:

Intermediate risk (9.1 to 9.9% mortality)

9 to 14 points:

High risk (31.4 to 34.9% mortality)

15 to 21 points:

Very High risk (61.5 to 66.2% mortality)

Data action

Include literature references: Yes No

Notes

This calculator represents findings from the literature referenced below. It is important to understand that these findings may not be representative of the experience in your local healthcare system.
O₂Sat is measured on room air.
ISARIC: International Severe Acute Respiratory and emerging Infections Consortium; 4C: Coronavirus Clinical Characterization Consortium.

Equations used

C4Score = AgeFactor + Sex + ComorbiditiesFactor + RespRateFactor + O₂SatFactor +GCSFactor + BUNFactor + CRPFactor

Calculation details and variables

AgeFactor is assigned values by this ordered logic:
- If Age ≥80 yr, AgeFactor = 7
- Else if Age ≥70 yr, AgeFactor = 6
- Else if Age ≥60 yr, AgeFactor = 4
- Else if Age ≥50 yr, AgeFactor = 2
- 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.
ComorbiditiesFactor is assigned values by this ordered logic:
- If Comorbidities ≥2 number, ComorbiditiesFactor = 2
- Else if Comorbidities ≥1 number, ComorbiditiesFactor = 1
- Else ComorbiditiesFactor = 0.
RespRateFactor is assigned values by this ordered logic:
- If Respiratory Rate ≥30 breaths/min, RespRateFactor = 2
- Else if Respiratory Rate ≥20 breaths/min, RespRateFactor = 1
- Else RespRateFactor = 0.
O2SatFactor is assigned values by this ordered logic:
- If O₂Sat <92 %, O2SatFactor = 2
- Else O2SatFactor = 0.
GCSFactor is assigned values by this ordered logic:
- If Glasgow Coma Scale <15 points, GCSFactor = 2
- Else GCSFactor = 0.
BUNFactor is assigned values by this ordered logic:
- If BUN >14 mmol/L, BUNFactor = 3
- Else if BUN ≥7 mmol/L, BUNFactor = 1
- Else BUNFactor = 0.
CRPFactor is assigned values by this ordered logic:
- If CRP ≥100 mg/L, CRPFactor = 2
- Else if CRP ≥50 mg/L, CRPFactor = 1
- Else CRPFactor = 0.

References

Knight SR, Ho A, Pius R, et al. Risk stratification of patients admitted to hospital with covid-19 using the ISARIC WHO Clinical Characterisation Protocol: development and validation of the 4C Mortality Score. BMJ. 2020 Sep 9;370:m3339. PubMed ID: 32907855
Aletreby WT, Mumtaz SA, Shahzad SA, et al. External Validation of 4C ISARIC Mortality Score in Critically ill COVID-19 Patients from Saudi Arabia. Saudi J Med Med Sci. 2022 Jan-Apr;10(1):19-24. PubMed ID: 35283713

Associated Medical Subject Headings [MeSH]

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 : %
Glasgow Coma Scale	9269-2 : score 35088-4 : score
BUN	3094-0 : mg/dL 6299-2 : mg/dL 14937-7 : mmol/L 59570-2 : mmol/L
CRP	1988-5 : mg/L 48421-2 : mg/L 76485-2 : nmol/L

This material contains content from LOINC (http://loinc.org). LOINC is copyright © 1995-2023, Regenstrief Institute, Inc. and the Logical Observation Identifiers Names and Codes (LOINC) Committee and is available at no cost under the license at http://loinc.org/license. LOINC® is a registered United States trademark of Regenstrief Institute, Inc.

Associated HCC ICD10-CM codes

U07.1

COVID-19

B97.29

Other coronavirus as the cause of diseases classified elsewhere

D68.69

Other Thrombophilia (COVID-19 associated hypercoagulability)

D68.8

Other Specified Coagulation Defects (COVID-19 associated coagulopathy)

J12.82

Pneumonia due to coronavirus disease

M35.81

Multisystem inflammatory syndrome.

M35.89

Other specified systemic involvement of connective tissue

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