Prediction scores ineffective for assessing group A streptococcus pharyngitis

Press release issued: 8 February 2024

Centor and McIsaac clinical prediction scores are ineffective at assessing patients who need antibiotics when they come to hospital with a sore throat.

Pharyngitis — also known as a sore throat — is an inflammation of the throat, caused by a viral or bacterial infection, which results in soreness, fever and discomfort during swallowing. Sore throats are common. Many adults and children are likely to develop one over the course of a year, but they usually get better by themselves without needing any additional treatment.

However, up to 30 per cent of pharyngitis cases are caused by group A streptococcus (GAS) bacteria. GAS pharyngitis can cause other serious complications to develop such as middle-ear infections, sinusitis or scarlet fever. The Centor and McIsaac scores were developed to predict how likely someone is to test positive for GAS if they have pharyngitis. They use a patient’s symptoms and clinical findings to help decide if antibiotics should be prescribed.

The study team reviewed 14 studies which reported using either the McIsaac or Centor scores to evaluate how likely patients were to develop GAS pharyngitis. They found little difference between using either score when it came to distinguishing which patients had GAS and which had non-GAS pharyngitis. Researchers established that, in both cases:

at high clinical thresholds, too many true positive cases are missed
at low clinical thresholds, too many false positives are treated

Read the full news item on the NIHR ARC West website

Paper: Kanagasabai A et al. (2024). Systematic review and meta-analysis of the accuracy of McIsaac and Centor score in patients presenting to secondary care with pharyngitis. Clinical Microbiology and Infection.