Criteria

Clinical prediction scores for distinguishing between viral and GAS pharyngitis (such as Centor, McIsaac, and FeverPain) are available, but are not recommended to guide decisions on testing and treatment in patients with suspected scarlet fever in many countries, such as the UK.[25] Refer to your local protocol for specific recommendations in your area.

Centor score

Around 90% of children and adolescents with scarlet fever also present with group A streptococcus (GAS) (Streptococcus pyogenes) pharyngitis.[17][18]​ The Centor score estimates the probability of GAS pharyngitis in patients aged ≥15 years. A score of 1 point is assigned to each of the following criteria:[30][31]

  • Tonsillar swelling or exudate

  • Tender anterior cervical adenopathy

  • No cough

  • Temperature >38°C (>100.4°F).

Patients with a total score of ≥3 should be considered for rapid antigen detection testing or culture for GAS from a throat swab.[30]

McIsaac score (modified Centor score)

This McIsaac score uses the same criteria as the Centor score, but corrects for age and so it can be used in children and in adults.[40][45] [ Sore Throat (Pharyngitis) Evaluation and Treatment Criteria (McIsaac) Opens in new window ] As with the Centor score, patients with a total score of ≥3 should be considered for rapid antigen detection testing or culture for GAS from a throat swab.[30]

FeverPAIN criteria

FeverPAIN criteria includes:[46]

  • Fever (during previous 24 hours)

  • Purulence (pus on tonsils)

  • Attend rapidly (within 3 days after onset of symptoms)

  • Severely inflamed tonsils

  • No cough or coryza (inflammation of mucous membranes in the nose).

Each of the FeverPAIN criteria scores 1 point (maximum score of 5). Higher scores suggest more severe symptoms and likely a bacterial (streptococcal) cause. A score of 0 or 1 is thought to be associated with a 13% to 18% likelihood of isolating Streptococcus. A score of 2 or 3 is thought to be associated with a 34% to 40% likelihood of isolating Streptococcus. A score of 4 or 5 is thought to be associated with a 62% to 65% likelihood of isolating Streptococcus.[46]

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