- General medicine
- ENT
- Infectious Diseases
McIsaac score
Probability of strep throat
The McIsaac score, or modified Centor score, combines clinical signs of pharyngitis with age to estimate the probability of a group A beta-hemolytic streptococcus infection. It helps select patients for whom microbiological testing is appropriate according to local guidelines. It should not automatically trigger an antibiotic prescription.
- Number of questions
- 4 clinical criteria and 1 age adjustment
- Approximate duration
- ≈ 1 minute
- Population
- patients with pharyngitis/tonsillitis, aged 3 years and older in the original validation
- Modality
- clinical score
QuestionnaireMcIsaac
CLINICIAN SCORE
The clinician checks for four signs (temperature > 38 °C, absence of cough, tender anterior cervical lymphadenopathy, tonsillar exudate or swelling), each scoring 1 point, and then adds an age adjustment (+1 for ages 3 to 14, 0 for ages 15 to 44, −1 for ages 45 and older), giving a total score from −1 to 5.
Are you patient?
The score requires an examination of the throat and lymph nodes. It cannot be used on its own to decide whether an antibiotic is necessary.
Question 1 / 5
Temperature > 38 °C
Terms of contract
The score is calculated by a healthcare professional after taking the temperature and examining the throat and cervical lymph nodes in a patient aged 3 years or older presenting with a sore throat. According to the French National Authority for Health (HAS), a rapid antigen detection test (RADT) is systematically performed in children over 3 years old, and in adults if the score is ≥ 2; the score alone does not determine the need for antibiotic therapy.
Score interpretationMcIsaac
Total score: +1 per clinical criterion present, +1 for age 3–14 years, 0 for 15–44 years, −1 for ≥ 45 years; score from −1 to 5.
Total score
First reading
The probability of a streptococcal infection increases with the score; the next step should be defined by current French or local guidelines, in particular the use of a rapid diagnostic test.
The score does not distinguish between all causes of pharyngitis and its performance varies according to age and the local prevalence of streptococcus.
Frequently asked questions
Sources and references
McIsaac WJ et al.
McIsaac WJ, White D, Tannenbaum D, Low DE. A clinical score to reduce unnecessary antibiotic use in patients with sore throat. CMAJ. 1998;158(1):75–83.
Questionnaires and associated scores
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