Centor Score Calculator

The Centor score calculator helps estimate the probability of streptococcal pharyngitis in children and adults based on clinical data.

Before diving into the Centor criteria calculator, let’s review some basics.

Evidence-Based Studies:

In 1981, Dr. Robert Centor conducted a study aimed at developing criteria to diagnose Group A Streptococcus (GAS) infection in adult patients presenting with a sore throat in the emergency department. The original model identified 4 Centor criteria:

Absence of cough
Tonsillar exudates (ooze)
History of fever
Swollen, tender anterior cervical adenopathy

Patients exhibiting all 4 variables had a 56% probability of having a Group A β-haemolytic Streptococcus (GABHS) infection. The probabilities for fewer criteria were:

3 variables: 32%
2 variables: 15%
1 variable: 6.5%
0 variables: 2.5%

Chart and Modified Centor Score:

In 1998, Dr. Warren McIsaac modified the Centor score to include age. The modified Centor score has been validated (McIsaac et al., 2004) for both adults and children presenting with sore throat. Using the Centor Score helps reduce unnecessary initial antibiotic prescriptions by 48% without increasing throat culture use.

The modified Centor criteria incorporate age as follows:

Age under 15: add 1 point
Age over 44: subtract 1 point

About Centor Criteria:

In simple terms, the Centor criteria are used to evaluate the probability of a streptococcal infection in patients complaining of a sore throat. These criteria were developed to quickly diagnose the presence of Group A Streptococcal infection in patients visiting emergency departments. You can use a Centor Score calculator to determine your strep criteria score.

Mnemonic for Centor Criteria:

Centor stands for:

C – Cough absent (“Can’t Cough”)
E – Exudate
N – Nodes (swollen, tender anterior cervical lymph nodes)
T – Temperature (fever)
OR – Young OR Old modifier (age adjustment)

About Centor Score Calculator:

The Centor criteria calculator evaluates whether the pharyngitis (sore throat) presented in the patient can be of streptococcal cause. In addition, the calculator provides recommendations on whether to pursue further testing.

How to Calculate Centor Score With This Calculator:

This strep throat score calculator has a user-friendly interface that helps you find your Centor or strep score instantly. You need to enter the five criteria included in the score:

Enter your age in years into the designated box.
Select 'Yes' or 'No' for "Exudate or swelling on tonsils."
Select 'Cough' if present, or 'No Cough' if absent from the drop-down menu.
Select 'Yes' or 'No' for "Tender/Swollen anterior cervical lymph nodes."
Enter your current body temperature and choose whether it is in °C or °F.
Click the calculate button. The Centor Score Calculator will display your score and further recommendations based on your clinical data.

Elaboration on Scoring Method:

Pharyngitis (sore throat) is a common presentation caused by various factors, including streptococcal infection, which often occurs in young children. The strep throat score facilitates the initial diagnosis and offers recommendations to clinicians on whether further testing (such as a strep culture) is needed.

The five Centor criteria included in the score are:

Patient age – low probability of GAS in children younger than 3 or in the elderly.
Exudate or swelling on tonsils.
Tender/Swollen anterior cervical lymph nodes.
Fever greater than 38°C (100.4°F).
Cough presence.

Presence of three or four of these clinical signs indicates the need for further diagnosis of Group A beta-haemolytic streptococcus (GABHS). Patients with a 40-60% probability may require antibiotic treatment. Conversely, absence of these signs suggests a negative diagnosis in 80% of cases, often indicating no need for antibiotics.

According to the National Institute for Health and Clinical Excellence (NICE), antibiotic therapy is recommended in cases with positive culture results or a Centor score higher than 3. However, the Centor score may produce false negatives when symptoms are mild or not fully expressed, which can delay appropriate therapy.

Result Interpretation:

Each of the five Centor criteria contributes differently to the final score. Age is categorized as follows:

3 to 14 years: 1 point
15 to 44 years: 0 points
45 years and above: -1 point

Centor Score Interpretation & Treatment Suggestions

Streptococcal pharyngitis is more common in children and young adults. Patients over 45 are considered highly unlikely to develop it, which is why the age criterion carries a -1 weight. The other four Centor criteria are risk factors for a positive diagnosis and are awarded 1 point each if present. The Centor score ranges from -1 to 5. The probability of a positive Group A β-hemolytic Streptococcus (GABHS) diagnosis varies according to the score.

Did You Know?

If the Rapid Strep Test is positive, the following antibiotic and supportive therapies may be suggested:

Penicillin V Potassium 250 mg Tab
Azithromycin 250 mg Tab
Amoxicillin 875 mg Tab
Cephalexin 500 mg Tab

If the Rapid Strep Test is negative, supportive therapy may include:

Acetaminophen ER 650 mg Tab
Benzocaine-Menthol 6 mg-10 mg Lozenges
Ibuprofen 400 mg Tab

Note: Always consult a medical professional before taking any of the above medications!

Frequently Asked Questions

What is the Modified Centor Score?

The Modified Centor Score, also known as the McIsaac Score, helps predict the probability of streptococcal pharyngitis by considering risk factors such as:

Patient's age
Symptoms
Physical exam findings

Which antibiotics treat pharyngitis?

Penicillin or amoxicillin are commonly used to treat Group A strep pharyngitis. Clinical isolates of Group A strep resistant to penicillin have not been reported, but resistance to clarithromycin and azithromycin can occur in some communities.

What is Strep A?

Group A streptococcus (GAS) is a bacterium commonly found in the throat or on the skin. Individuals may carry GAS without symptoms. Most GAS infections are relatively mild illnesses, such as strep throat or impetigo.

How did I get pharyngitis?

Pharyngitis is caused by inflammation in the back of the throat (pharynx) between the tonsils and the voice box (larynx). Most sore throats are caused by cold, flu, coxsackie virus, or mononucleosis. Strep throat is caused by Group A streptococcus (GABHS).

Does strep stay in your body forever?

Strep infections typically resolve on their own. The immune system usually clears the bacteria over time.

Disclaimer:

The Centor Score Calculator is intended for informational and educational purposes only. The authors make no claims regarding the accuracy of the information contained herein. For medical concerns regarding Centor criteria or treatment, consult a qualified healthcare professional.

References:

BETH A. CHOBY, MD, University of Tennessee College of Medicine–Chattanooga. Am Fam Physician. 2009 Mar 1;79(5):383-390 - Diagnosis and Treatment of Streptococcal Pharyngitis
Centers for Disease Control and Prevention - CDC - Group A Strep Home - For Clinicians - Group A Streptococcal (GAS) Disease
Clinical Infectious Diseases, Volume 35, Issue 2, 15 July 2002, Pages 126–129 - Diagnosis of Strep Throat in Adults
National Institute for Health and Care Excellence - Sore throat (acute): antimicrobial prescribing NICE guideline [NG84] - Terms used in the guideline - FeverPAIN criteria and Centor criteria