From the Guidelines
The Centor score is a clinical prediction tool used to assess the likelihood of group A streptococcal pharyngitis (strep throat) in patients presenting with sore throat, consisting of four criteria: fever, absence of cough, tender anterior cervical lymphadenopathy, and tonsillar exudates, with a total score from 0-4. The criteria are assigned points as follows:
- Fever ≥38°C (100.4°F): 1 point
- Absence of cough: 1 point
- Tender anterior cervical lymphadenopathy: 1 point
- Tonsillar exudates: 1 point A score of 0-1 suggests a low risk of strep throat (less than 10%), and antibiotics are not recommended 1. A score of 2-3 indicates moderate risk (15-35%), and rapid strep testing or throat culture should be performed before considering antibiotics 1. A score of 4 indicates high risk (over 50%), and empiric antibiotic treatment may be considered, though testing is still preferred 1. If antibiotics are needed, penicillin V (500 mg twice daily for 10 days) or amoxicillin (500 mg twice daily for 10 days) are first-line treatments, with macrolides as alternatives for penicillin-allergic patients. The Centor score helps clinicians make more judicious decisions about antibiotic use, reducing unnecessary prescriptions while identifying patients who would benefit from treatment. Some key points to consider when using the Centor score include:
- The score is only validated in adults and not in children, although a modified version has been validated in children aged 3-15 years 1
- The score should be used in conjunction with clinical judgment and other diagnostic tools, such as rapid strep testing or throat culture, to guide antibiotic use 1
- Antibiotics should not be used in patients with low risk of strep throat (score 0-1) or in patients with moderate risk (score 2-3) without confirmatory testing 1
From the Research
Definition of the Centor Score
The Centor score, also known as the Centor criteria, is a clinical prediction rule used to estimate the probability of group A β-haemolytic streptococcal (GABHS) pharyngitis in adults presenting with sore throat symptoms 2, 3, 4, 5.
Components of the Centor Score
The Centor score consists of four clinical criteria:
- Cervical adenopathy
- Tonsillar exudate
- Fever
- Absence of catarrh symptoms
Diagnostic Accuracy of the Centor Score
Studies have shown that the Centor score has reasonable specificity and can be used to estimate the probability of GABHS pharyngitis 4, 5. However, individual signs and symptoms are not powerful enough to discriminate GABHS pharyngitis from other types of sore throat 4.
Clinical Application of the Centor Score
The Centor score can be used to stratify patients with a sore throat into different probabilities of having an underlying bacterial or viral cause, which can help target antibiotic treatment 3, 4. A Centor score of 3 or 4 may indicate a higher probability of GABHS pharyngitis, but further examination is often required to confirm the diagnosis 5.
Comparison with Other Diagnostic Tools
The Centor score has been compared to other diagnostic tools, such as the streptococcal rapid antigen detection test (RADT) and infection markers like procalcitonin, C-reactive protein, and white blood cell count 6. While these tools may have some diagnostic value, the Centor score remains a useful clinical prediction rule for estimating the probability of GABHS pharyngitis.
Key Findings
Some key findings from studies on the Centor score include:
- A Centor score of 3 or 4 has a positive predictive value of 48.1% and a negative predictive value of 81.4% for GABHS pharyngitis 2
- The Centor score has reasonable specificity (0.82,95% CI 0.72 to 0.88) and a post-test probability of 12% to 40% based on a prior prevalence of 5% to 20% 4
- A Centor score < 3 is favorable for excluding a diagnosis of GABHS pharyngitis 5