🦠 Centor Score Strep Throat Simulator

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.