Criteria for the Centor Score
The Centor score consists of four criteria: fever (>38.5°C), absence of cough, tonsillar exudates, and tender anterior cervical lymphadenopathy. 1
Detailed Explanation of Centor Criteria
The Centor score is a clinical decision tool used to assess the probability of Group A Streptococcal (GAS) infection in patients presenting with sore throat. Each criterion contributes one point to the total score:
- Fever by history or present (>38.5°C) - Patient reports fever or has measured temperature above 38.5°C
- Absence of cough - No significant coughing symptoms
- Tonsillar exudates - Visible white or yellow patches on the tonsils
- Tender anterior cervical lymphadenopathy - Swollen, painful lymph nodes in the front of the neck
Interpretation of Centor Score
The risk of Group A streptococcal infection increases with the Centor score 1:
| Centor Score | Risk of GAS Infection |
|---|---|
| 0 | 2.5% |
| 1 | 5-10% |
| 2 | 11-17% |
| 3 | 28-35% |
| ≥4 | 51-53% |
Modified Centor Score
The original Centor score was later modified to include age as an additional criterion 1. The modified Centor score (McIsaac score) adds:
- Age 3-14 years: +1 point
- Age 15-44 years: 0 points
- Age ≥45 years: -1 point
Clinical Application
The Centor score helps clinicians determine the need for further testing and antibiotic treatment:
- Score 0-1: Low risk of streptococcal infection; no testing or antibiotics recommended
- Score 2-3: Intermediate risk; consider rapid antigen detection test (RADT)
- Score ≥4: High risk; consider empiric antibiotic treatment or RADT
Limitations of the Centor Score
Age-dependent validity: The original Centor score was validated only in adults, not in children 1. Research shows it has lower utility in children because of different clinical presentations 2, 3.
Limited sensitivity and specificity: Even with a high Centor score, the likelihood of GAS infection is only around 50-53% 1.
Missing important signs: Some studies suggest that additional signs like palatal petechiae may improve diagnostic accuracy. One study found that 75% of children with palatal petechiae had positive throat cultures for strep 4.
Differential importance of criteria: Clinicians tend to give more weight to certain criteria, particularly tonsillar exudate and lymphadenopathy, even though research doesn't support this prioritization 3.
Best Practices for Using the Centor Score
Use the score as a screening tool, not as a definitive diagnostic test.
Consider rapid antigen detection tests (RADTs) for patients with Centor scores ≥2, as this approach has been shown to reduce unnecessary antibiotic prescriptions 5.
Remember that the presence of viral symptoms (cough, rhinorrhea, hoarseness, oral ulcers) suggests a viral rather than bacterial etiology 6.
Be aware that in children, the Centor criteria may be less reliable for predicting GAS pharyngitis 2.
The Centor score remains a valuable clinical tool for initial assessment of sore throat, but should be used in conjunction with laboratory testing when appropriate to guide antibiotic stewardship and improve patient outcomes.