Infectious disease
Centor score (McIsaac modified)
The Centor score estimates how likely a sore throat is to be streptococcal, and therefore whether testing or an antibiotic is warranted. The McIsaac modification adds an age adjustment, which matters in a pediatric population.
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This calculator is provided for reference and education. It does not replace clinical assessment, examination, current guidelines, local protocol, or professional judgment. Verify every result before acting on it. Nirogix accepts no liability for clinical decisions made using this tool.
The formula
- Exudate 1 · Tender nodes 1 · Fever above 38 °C 1 · Cough absent 1
- McIsaac age adjustment: +1 for 3–14 years, 0 for 15–44, −1 for 45 and over
Worked example
A 10-year-old with exudate, tender nodes and fever, no cough → 4 + 1 = 5, high probability
When to use it
- An acute sore throat where the antibiotic decision is genuinely open
And when not to
- It does not apply under 3 years of age, where streptococcal pharyngitis is uncommon and presents differently.
- It cannot distinguish carriage from infection.
- Local antibiotic guidance and rheumatic fever prevalence change the threshold to treat, and in India that argument is not settled by a score alone.
References
- The diagnosis of strep throat in adults in the emergency room — Centor RM et al., Medical Decision Making, 1981
- A clinical score to reduce unnecessary antibiotic use — McIsaac WJ et al., CMAJ, 1998
Last reviewed 07/09/2026.
These calculators are free and always will be. We also build Nirogix, a hospital management system for Indian clinics and hospitals. The same calculations are planned inside the consultation record, pre-filled from the chart.