Centor criteria to aid diagnosis of Group A beta-haemolytic streptococcus

The Centor criteria is sometimes used to aid diagnosis of Group A beta-haemolytic streptococcus (GABHS) as a cause of presentation with a sore throat. A Centor score < 3 is favourable for excluding a diagnosis of GAS pharyngitis. Centor scores 3 and 4 require further examination to confirm a diagnosis of GAS pharyngitis. (1) It scores:

• tonsillar exudate
• tender anterior cervical lymph nodes
• absence of cough
• history of fever
• presence of three or four of these clinical signs suggests that the chance of the patient having GABHS is between 40% and 60%, so the patient may benefit from antibiotic treatment
• absence of three or four of the signs suggests that there is an 80% chance that the patient doesn't have the infection, and antibiotics are unlikely to be necessary
• in patients with tonsillitis who are unwell, and have three out of four of these criteria, the risk of quinsy is 1:60 compared with 1:400 in those who are not unwell
• However, the Centor criteria is not ideal, and will lead to some patients with bacterial pharyngitis not being treated and result in unnecessary antibiotic treatment for others (2)

Reference:

1. Muthanna A et al. Diagnostic Accuracy of Centor Score for Diagnosis of Group A Streptococcal Pharyngitis among Adults in Primary Care Clinics in Malaysia. Malays J Med Sci. 2022 Aug;29(4):88-97.
2. Evans C et al. Systematic review and meta-analysis of the accuracy of McIsaac and Centor score in patients presenting to secondary care with pharyngitis. Clin Microbiol Infect. 2024 Apr;30(4):445-452.