Centor / McIsaac (strep pharyngitis)
Centor / McIsaac (strep pharyngitis) - a deterministic tool in Sophie Well's Clinical Scoring & Risk group.
Open the Centor / McIsaac (strep pharyngitis) → Runs in your browser. No signup, no tracking.
What this is
Score the four-criterion Centor rule for adult pharyngitis with the McIsaac age adjustment: one point each for tonsillar exudate, tender anterior cervical lymphadenopathy, history of fever, and absence of cough; plus one point for age 3-14, zero points for 15-44, and minus one point for >=45. Sophie Well returns the total score, the IDSA / CDC-aligned probability band for group A streptococcus, and the testing and treatment recommendation that pairs with that band.
When to use it
Use this for a primary-care or urgent-care visit for sore throat to decide whether the encounter needs a rapid strep test, a culture, empiric antibiotics, or symptomatic care only. The score is calibrated for ambulatory adults and older children with acute pharyngitis - it is not validated for immunocompromised hosts, recurrent tonsillitis under chronic management, or patients with peritonsillar abscess or other suppurative complications. A score in the low band predicts strep prevalence under 10% and is the strongest tool clinicians have for not prescribing antibiotics in viral pharyngitis.
References
Centor RM, et al. Med Decis Making. 1981;1(3):239-246. McIsaac WJ, et al. CMAJ. 1998;158(1):75-83.
Worked example: Centor 4; McIsaac 5 (high probability of GAS pharyngitis; consider testing or empiric treatment).
Sophie Well is a reference and educational tool. Not medical, legal, or financial advice. Does not replace clinician judgment, professional billing review, or legal counsel.