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Centor Score Calculator (Modified/McIsaac)

Created by Łukasz Białek, MD
Reviewed by Bogna Szyk and Steven Wooding
Based on research by
Centor RM, Witherspoon JM, Dalton HP, Brody CE, Link K. The diagnosis of strep throat in adults in the emergency room.; Medical Decision Making; 1981
Last updated: Feb 28, 2024


Centor score calculator estimates the probability that pharyngitis is caused by a streptococcal infection. It is based on the Centor criteria (modified/McIsaac), which consist of five simple clinical data.

Keep on reading to find out:

  • What is the basis of Centor criteria?
  • How to calculate the Centor score?
  • What does the result of the Centor score tell you?

We try our best to make our Omni Calculators as precise and reliable as possible. However, this tool can never replace a professional doctor's assessment.

What is the basis of Centor criteria?

In 1981, Dr. Robert Centor, with associates, published an article in Medical Decision Making. Its goal was to see if clinical findings could stratify the probability that an adult patient with a sore throat had group A Streptococcus.

They analyzed 234 patients who filled out their questionnaire and had throat cultures performed. They noticed that the set of four variables could decently predict the positive culture. Almost two decades later, Dr. Warren McIsaac modified the scale by adding the fifth variable – age.

How to calculate Centor score?

The Centor (Modified/McIsaac) criteria is a kind of strep throat criteria and consists of four variables:

  • Fever >38 °C / 100.4 °F;
  • Tonsillar exudates;
  • Tender anterior cervical lymphadenopathy; and
  • Absence of a cough.

Each of them may give you 1 point. The fifth variable — age — may give you -1, 0, or +1 points.

Body temperature

Fever >38 °C / 100.4 °F

1

No fever nor feverishness

0

Tonsils

Tonsillar exudates

1

No exudate

0

Lymph nodes

Lymphadenopathy

1

No lymphadenopathy

0

Cough

Cough

0

No Cough

1

Age

<15

1

16-44

0

>45

-1

Use the temperature conversion tool to convert between Celsius and Fahrenheit.

What does the result of Centor score tell you?

The greater the Centor score, the bigger the probability of streptococcal infection causing pharyngitis.

Centor score

Probability of positive culture

4 or 5

51%-53%

3

28%-35%

2

14%-16%

1

5%-7%

0

1%-3%

The interpretation of the Centor score should be as follows:

  • 0-1 point: no further testing or antibiotics are required.

  • 2-3 points: culture test should be taken; antibiotics only needed with positive culture results.

  • 4-5 points: treat empirically with antibiotics.

Let's get an example!

A 24-year-old male student came to the doctor due to a sore throat, which started on the day before the visit. The patient also reports productive cough, sneezing, and a runny nose. His body temperature is 37.8 Celcius. He denies pain in the neck. On medical examination, there are enlarged, swollen tonsils with exudate. However, there is no lymphadenopathy.

To assess appropriate patient management concerning possible bacterial etiology of pharyngitis, a doctor should calculate the Centor score. The patient receives: body temperature — 0 points, tonsils — 1 point, lymph nodes — 0 points, cough — 0 points, and age — 0 points. Altogether — 1 point. In this case, no antibiotic or throat culture is necessary, as the risk of streptococcal infection is 5%-7%.

You might also be interested in our sepsis calculator or the amoxicillin pediatric dosage calculator.

Warning!
Using any calculator may never replace a medical examination. If you feel any symptoms, contact your physician!

Łukasz Białek, MD
Body temperature
°F
Tonsils
Select...
Lymph nodes
Select...
Cough
Select...
Age
years
Centor Score
pts
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