Modified Centor (McIsaac) Score for Group A Strep Pharyngitis Calculator

Calculate the McIsaac Modified Centor score from clinical criteria and patient age.

Modified Centor (McIsaac) Score
3 points (−1 to 5)
Estimated Group A Strep Probability 32 %
Classic 4-Criteria Centor Score 3 pts (0–4)
McIsaac Age Adjustment 0 pts
Inputs
⚡ Scenarios:
0 or 1
Absence of cough (1 = no cough, 0 = cough present).
0 or 1
Swollen, tender anterior cervical lymph nodes (1 = yes, 0 = no).
0 or 1
Tonsillar exudates or swelling (1 = yes, 0 = no).
0 or 1
Temperature > 38.0 °C (100.4 °F) (1 = yes, 0 = no).
years
Patient age in years (+1 pt if 3–14 yrs, 0 pt if 15–44 yrs, −1 pt if ≥45 yrs).
Results & Graph
Modified Centor (McIsaac) Score
3 points (−1 to 5)
Estimated Group A Strep Probability
32 %
Classic 4-Criteria Centor Score
3 pts (0–4)
McIsaac Age Adjustment
0 pts

Modified Centor (McIsaac) Score

Graph 1 • Centor / McIsaac Strep Score • Domain Architecture & Live Telemetry Maps Absence Of Cough0or1, Swollen Tender Nodes0or1, Tonsillar Exudate Or Swelling0or1 through Centor / McIsaac Strep Score Formula.
Centor / McIsaac Strep Score • Clinical & Physiological Reference Scale Low / Baseline Target / Reference Elevated / Watch High / Action Modified Centor (McIsaac) Score: 3 points (−1 to 5) Estimated Group A Strep Pr 32 % Classic 4-Criteria Centor 3 pts (0–4) McIsaac Age Adjustment 0 pts
Graph 2 • Modified Centor (McIsaac) Score Across Absence Of Cough0or1 Sweep (40% → 160%) Evaluates Score = AbsenceOfCough (1) + TenderAnteriorCervicalNodes (1) + Fever>38° across 7 operating points (current input highlighted).
0 points 1.65 points 3.30 points 2 0.400 3 0.600 3 0.800 3 1 3 1.20 3 1.40 3 1.60
Graph 3 • Joint Sensitivity: Absence Of Cough0or1 × Swollen Tender Nodes0or1 Compares Modified Centor (McIsaac) Score when Swollen Tender Nodes0or1 is shifted +25% (solid) vs. −25% (dashed).
0 points 1.65 points 3.30 points --- Swollen Tender Nodes0or1 @ 75% 3 -30% 3 -15% 3 +0% 3 +15% 3 +30%
Summary: Modified Centor score is 3 (Classic 4-item Centor = 3/4; estimated Group A Strep probability ~32%).
Summary: Modified Centor score is 3 (Classic 4-item Centor = 3/4; estimated Group A Strep probability ~32%).
⚡ Send result to: BMI →Calorie & TDEE →Pace, 1RM & HR Zones →
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Formula & Mathematical Methodology: Centor / McIsaac Strep Score Formula

Score = AbsenceOfCough (1) + TenderAnteriorCervicalNodes (1) + Fever>38°C (1) + TonsillarExudate (1) + AgeModifier (+1 if 3–14, −1 if ≥45)
Score = AbsenceOfCough (1) + TenderAnteriorCervicalNodes (1) + Fever>38°C (1) + TonsillarExudate (1) + AgeModifier (+1 if 3–14, −1 if ≥45)
  • absenceOfCough0or1: Absence Of Cough0or1 (0 or 1)
  • swollenTenderNodes0or1: Swollen Tender Nodes0or1 (0 or 1)
  • tonsillarExudateOrSwelling0or1: Tonsillar Exudate Or Swelling0or1 (0 or 1)
  • feverOver38C0or1: Fever Over38 C0or1 (0 or 1)
  • patientAgeYears: Patient Age Years (years)

Rounding: Clinical scores round to statutory integer or decimal precision; physiological metrics round to 2 decimal places.

Worked Example: Clinical / Physiology Scenario: Centor / McIsaac Strep Score

Calculate the McIsaac Modified Centor score from clinical criteria and patient age.

  1. Enter lab values, anthropometric measurements, or performance test metrics.
  2. Evaluate the reference equation: Score = AbsenceOfCough (1) + TenderAnteriorCervicalNodes (1) + Fever>38°C (1) + TonsillarExudate (1) + AgeModifier (+1 if 3–14, −1 if ≥45).
  3. Inspect the primary classification, supporting indices, and 3 SVG charts.
Result: Computes Centor / McIsaac Strep Score via Score = AbsenceOfCough (1) + TenderAnteriorCervicalNodes (1) + Fever>38°C (1) + TonsillarExudate (1) + AgeModifier (+1 if 3–14, −1 if ≥45).

Frequently Asked Questions

How does the Modified Centor (McIsaac) Score for Group A Strep Pharyngitis Calculator compute its result?

It evaluates Score = AbsenceOfCough (1) + TenderAnteriorCervicalNodes (1) + Fever>38°C (1) + TonsillarExudate (1) + AgeModifier (+1 if 3–14, −1 if ≥45) directly in your browser and updates three custom SVG visualizations in real time.

Can I use Goal Seek to solve backwards for a target lab value or pace?

Yes. Click "🎯 Goal Seek" in the results toolbar to solve backwards for any numeric input parameter.

Are my health and biometric inputs kept private?

Yes. All calculations run 100% locally on your device with zero external transmission.

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Modified Centor (McIsaac) Score for Group A Strep Pharyngitis Calculator: inputs, method, and how to read the result

Calculate the McIsaac Modified Centor score from clinical criteria and patient age.

Choose inputs for the case you are checking

The defaults are illustrative. Replace them with values for your case and keep the units shown beside each field.

  • Absence Of Cough0or1: Absence of cough (1 = no cough, 0 = cough present).
  • Swollen Tender Nodes0or1: Swollen, tender anterior cervical lymph nodes (1 = yes, 0 = no).
  • Tonsillar Exudate Or Swelling0or1: Tonsillar exudates or swelling (1 = yes, 0 = no).
  • Fever Over38 C0or1: Temperature > 38.0 °C (100.4 °F) (1 = yes, 0 = no).

What the calculation includes

With the default values shown, Modified Centor (McIsaac) Score is 3 points (−1 to 5). The calculation follows Centor / McIsaac Strep Score Formula; the formula and variable definitions above show how the inputs combine.

One-input check: With the other defaults held constant, changing Absence Of Cough0or1 from 1 0 or 1 to 0 0 or 1 changes Modified Centor (McIsaac) Score from 3 points (−1 to 5) to 2 points (−1 to 5). This is a comparison inside the calculator's stated model, not a prediction.

Where to use caution

  • Uses peer-reviewed clinical and sports physiology formulas.
  • For educational and informational reference only; clinical scores do not replace physician judgment or laboratory reference ranges.

Scope: Global Clinical & Sports Science Consensus Check the assumptions and limitations against your situation before relying on the estimate.

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