Patient Presents With Sore Throat
Sore throat is one of the most common outpatient complaints.
- ~13M: Sore throat visits/yr (US) (primary care)
- 5–15%: Adults with strep (of sore throats)
- 20–30%: Children with strep (of sore throats)
- ~60%: Untreated abx use (historically over-prescribed)
Why this matters
Most sore throats are viral. Antibiotics help only bacterial strep.
The diagnostic problem
Symptoms alone can't reliably separate viral from strep pharyngitis.
Overtreatment drives resistance and side effects.
A scoring solution
Centor criteria give a fast, structured bedside estimate.
The Four Centor Criteria
Four simple exam findings drive the score.
- 4: Criteria total (binary signs)
- 1: Points each (per criterion)
- <2 min: Exam time (bedside only)
- 1981: Published (Centor et al.)
Tonsillar exudate
White-yellow coating on the tonsils.
Tender cervical nodes
Swollen, tender anterior neck lymph nodes.
Each present criterion adds one point.
Fever and cough
Fever over 38°C and absence of cough complete the set.
The Score, Live and Age-Adjusted
The McIsaac variant adds an age correction to the raw count.
- -1 to 5: Score range (McIsaac scale)
- +1: Child bonus (ages 3–14)
- -1: Older penalty (ages 45+)
- 0: Adult adjustment (ages 15–44)
Raw Centor count
Sum the 4 present criteria, 0 to 4 points.
McIsaac age term
Age shifts the score since strep is more common in children.
Higher score, higher strep probability.
Probability mapping
Each total score maps to an approximate strep likelihood.
Risk-Stratified Decision Pathway
The score routes patients down one of three branches.
- No test: Score 0–1 (no antibiotics)
- Test: Score 2–3 (rapid strep / culture)
- Treat: Score ≥4 (empiric antibiotics)
- 3: Branches (risk tiers)
Low risk
Low score patients skip testing and antibiotics entirely.
Intermediate risk
Mid scores get a rapid antigen test to confirm before treating.
Testing spares low-probability patients from antibiotics.
High risk
High scores may warrant empiric treatment or test-and-treat.
Targeted Treatment vs Treat-All Baseline
Score-guided care cuts unnecessary antibiotic exposure.
- 100%: Baseline abx rate (treat-all approach)
- varies: Guided abx rate (by score tier)
- overuse: Resistance driver (unneeded antibiotics)
- match: Goal (treatment to true risk)
Antibiotics avoided
Score-guided testing withholds antibiotics from low-risk patients.
Population impact
Fewer unnecessary prescriptions slow resistance development.
Right test, right patient, right treatment.
Clinical takeaway
Centor/McIsaac scoring is a simple, validated triage tool.