Infectious Disease

McIsaac Modified Centor Score for Strep Pharyngitis

Calculates McIsaac score (-1 to 5) to stratify Group A Strep probability and direct Rapid Strep Testing (RADT) vs antibiotics.

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Parameters

McIsaac Modified Centor Score for Strep Pharyngitis Result

Formula

McIsaac Score = Fever (+1) + No Cough (+1) + Tender Ant Cervical Nodes (+1) + Tonsillar Exudate (+1) + Age [3–14y: +1, 15–44y: 0, ≥45y: -1]

Clinical Pearls

Safely eliminates over 50% of unnecessary antibiotic prescriptions for acute sore throat while reliably detecting treatable streptococcal pharyngitis to prevent acute rheumatic fever and peritonsillar abscess.

Limitations

Not validated in children younger than 3 years of age, as GABHS pharyngitis and acute rheumatic fever are exceptionally rare in infancy.