Centor and McIsaac score for sore throat
The Centor score estimates how likely group A streptococcal infection is in a patient with sore throat. In 1998, McIsaac added an age adjustment so that the score can also be used in children aged 3 years and older.
⚠︎ Learning tool for medical education – not for use in patients or for treatment decisions.
Classification (original publication)
| Score | Classification (original publication) |
|---|---|
| ≤ 0 | Group A strep unlikely – proportion with group A strep: McIsaac 1998 2.5%, McIsaac 2000 1% |
| 1 | Group A strep unlikely – proportion with group A strep: McIsaac 1998 5.1%, McIsaac 2000 10% |
| 2 | Intermediate probability – proportion with group A strep: McIsaac 1998 11.2%, McIsaac 2000 17% |
| 3 | Intermediate probability – proportion with group A strep: McIsaac 1998 27.8%, McIsaac 2000 35% |
| ≥ 4 | High probability – proportion with group A strep: McIsaac 1998 52.8%, McIsaac 2000 51% |
Centor and McIsaac
The original Centor score (1981) was derived in adults in the emergency department and has four criteria (0–4 points; history of fever, tonsillar exudate, lymph nodes, absent cough). The McIsaac score uses almost the same criteria (temperature > 38 °C by history or measured; tonsillar swelling or exudate instead of exudate alone), adds one point for children aged 3–14 years and subtracts one point for patients aged 45 years or older.
Limitations
The score estimates a probability; it does not prove streptococcal infection. The percentages come from two Canadian studies by McIsaac (1998, 2000). In a large US study of more than 200,000 patients (Fine 2012) they were higher: 8, 14, 23, 37 and 55% for scores 0 to 4. The figures therefore differ; they depend on how common streptococci are in a given population.
FAQ
What is the difference between the Centor and McIsaac scores?▾
The McIsaac score is the Centor score with an age adjustment: +1 point for ages 3–14, −1 point for age 45 years or older.
References
- Centor RM et al. The diagnosis of strep throat in adults in the emergency room. Med Decis Making 1981;1:239–46. · PubMed
- McIsaac WJ et al. A clinical score to reduce unnecessary antibiotic use in patients with sore throat. CMAJ 1998;158:75–83. · PubMed
- McIsaac WJ, Goel V, To T, Low DE. The validity of a sore throat score in family practice. CMAJ 2000;163:811–5. · PubMed
- Fine AM, Nizet V, Mandl KD. Large-scale validation of the Centor and McIsaac scores to predict group A streptococcal pharyngitis. Arch Intern Med 2012;172:847–52. · PubMed
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Open in browser Download on the App StoreIntended purpose: learning tool for medical education only. Not intended for use in patients or for diagnostic or treatment decisions; not a medical device. Calculations follow the cited original publications; no guarantee of completeness or correctness. Last updated: 10/2026 · Dr. Pascal Bafteh