Modified Centor Score Calculator
Use this in patients with ≤3 days of acute pharyngitis. Fill out the criteria below, then click Submit.
Score:
Probability of Strep:
Recommendation:
Centor Score for Strep Pharyngitis
The Centor Score is a clinical tool used to estimate the probability that a patient with a sore throat has a group A streptococcal (GAS) infection. It evaluates five criteria: age, tonsillar exudates or swelling, tender/swollen anterior cervical lymph nodes, fever above 38°C (100.4°F), and the presence or absence of cough. Each factor contributes points to the overall score, which ranges from -1 to +5.
Originally devised by Centor et al. for adults and subsequently modified by McIsaac to include pediatric patients, the score helps clinicians decide whether to pursue rapid strep testing, culture, or empirical antibiotic therapy. A key advantage of the Centor Score is that it allows clinicians to reduce unnecessary antibiotics in patients who are at low risk for strep infection, while still ensuring that high-risk patients are tested and treated.
| Addition of Selected Points | |
|---|---|
| Criteria | Points |
Age
|
|
| Exudate or swelling on tonsils | No: 0 Yes: +1 |
| Tender/swollen anterior cervical lymph nodes | No: 0 Yes: +1 |
| Temp > 38℃ (100.4℉) | No: 0 Yes: +1 |
| Cough | Cough present: 0 Cough absent: +1 |
Facts & Figures
The total Centor Score can range from -1 (for older patients without other criteria) to +5 (for younger patients who fulfill all positive clinical criteria). Higher scores indicate a greater likelihood of strep pharyngitis.
| Centor Score | Probability of Strep Pharyngitis | Recommendation |
|---|---|---|
| 0 | 1–2.5% | No further testing or antibiotics |
| 1 | 5–10% | No further testing or antibiotics |
| 2 | 11–17% | Optional rapid strep test and/or culture |
| 3 | 28–35% | Consider rapid strep test and/or culture |
| ≥4 | 51–53% | Consider rapid strep test and/or culture. Empiric antibiotics may be appropriate. |
Interpreting the Score
Scores of 0 or 1 suggest a low risk of streptococcal pharyngitis, and most guidelines recommend against testing or antibiotics. Patients with scores of 2 or 3 fall into an intermediate-risk category, where rapid antigen detection tests or cultures can help confirm or rule out group A Streptococcus. A score of 4 or more increases the likelihood of a streptococcal infection beyond 50%, prompting many clinicians to test or potentially treat empirically, depending on clinical judgment and patient factors.
Ultimately, the Centor Score can reduce unnecessary antibiotic prescriptions by guiding providers to confirm strep infection in moderate-to-high-risk cases while avoiding unneeded therapy in low-risk scenarios. It remains a widely used, succinct tool for clinicians who wish to balance evidence-based practice, patient safety, and antibiotic stewardship.
