What is the best score for diagnosing sepsis and how is it calculated?

Best Score for Sepsis Diagnosis

The SOFA (Sequential Organ Failure Assessment) score is the gold standard for diagnosing sepsis, requiring an increase of ≥2 points from baseline in patients with suspected infection, while qSOFA serves as a rapid bedside screening tool outside the ICU. 1, 2

Primary Diagnostic Framework

For sepsis diagnosis, use SOFA score ≥2 points increase from baseline plus documented or suspected infection. 1, 3 The SOFA score assesses six organ systems (0-4 points each) with superior discrimination for in-hospital mortality (AUROC 0.74-0.79) compared to other scoring systems. 2, 4

SOFA Score Components (Calculate 0-4 points for each system):

Respiratory System: 1

• PaO2/FiO2 <400: 1 point
• PaO2/FiO2 <300: 2 points
• PaO2/FiO2 <200 with mechanical ventilation: 3 points
• PaO2/FiO2 <100 with mechanical ventilation: 4 points

Cardiovascular System: 1

• MAP <70 mmHg: 1 point
• Dopamine ≤5 or any dobutamine: 2 points
• Dopamine >5 OR epinephrine/norepinephrine ≤0.1 mcg/kg/min: 3 points
• Dopamine >15 OR epinephrine/norepinephrine >0.1 mcg/kg/min: 4 points

Hepatic: Bilirubin 1.2-1.9 mg/dL (1 point), 2.0-5.9 (2 points), 6.0-11.9 (3 points), ≥12.0 (4 points) 1

Coagulation: Platelets <150,000 (1 point), <100,000 (2 points), <50,000 (3 points), <20,000 (4 points) 1

Renal: Creatinine 1.2-1.9 mg/dL (1 point), 2.0-3.4 (2 points), 3.5-4.9 or urine <500 mL/day (3 points), ≥5.0 or urine <200 mL/day (4 points) 1

Neurological: Glasgow Coma Scale 13-14 (1 point), 10-12 (2 points), 6-9 (3 points), <6 (4 points) 1

Rapid Bedside Screening: qSOFA Score

Outside the ICU, use qSOFA (≥2 points) as your initial screening tool before calculating full SOFA. 1, 2 The qSOFA has three simple criteria (1 point each): 2

• Respiratory rate ≥22/min
• Systolic blood pressure ≤100 mmHg
• Altered mental status (GCS <15)

qSOFA ≥2 indicates high-risk patient requiring immediate full SOFA assessment and ICU-level care. 1 However, qSOFA has lower discrimination (AUROC 0.66-0.69) than SOFA for mortality prediction in ICU patients. 2

Critical Caveat on qSOFA

Do not use qSOFA alone for sepsis diagnosis—it is only a screening tool. 2 Research shows that NEWS2 and MEWS scores actually outperform qSOFA for predicting mortality and ICU transfer (NEWS2 AUROC 0.77 vs qSOFA 0.69), though qSOFA remains useful for its simplicity at bedside. 5

Alternative Risk Stratification: NEWS2

For initial emergency department evaluation, NEWS2 score provides superior discrimination (AUROC 0.77) compared to qSOFA. 6, 5 NEWS2 ≥7 indicates high risk, 5-6 moderate risk, 1-4 low risk, and 0 very low risk. 6

Special Consideration: Sepsis-Induced Coagulopathy (SIC)

For sepsis patients with thrombocytopenia, calculate the SIC score to identify coagulopathy requiring specific interventions. 7, 1 The SIC score is simpler than full DIC criteria and identifies patients at very high mortality risk (30-40%). 7

SIC Score Calculation (Total ≥4 = SIC diagnosis): 7

• Platelet count: <100,000/μL (2 points), 100,000-150,000/μL (1 point)
• PT ratio (INR): >1.4 (2 points), 1.2-1.4 (1 point)
• SOFA score: ≥2 (2 points), 1 (1 point)

SIC score ≥4 identifies patients with 95.7% negative predictive value for overt DIC and allows earlier detection of coagulopathy than traditional DIC criteria. 7, 3 The International Society on Thrombosis and Haemostasis recommends a two-step approach: screen with SIC, then confirm overt DIC if needed. 7, 3

Clinical Implementation Algorithm

1. Identify suspected infection (fever, leukocytosis, elevated procalcitonin/CRP) 6
2. Calculate qSOFA at bedside for rapid risk assessment 1
3. If qSOFA ≥2: Calculate full SOFA score immediately 1
4. If SOFA increases ≥2 points from baseline: Diagnose sepsis 1, 3
5. Check for septic shock: Vasopressors needed for MAP ≥65 mmHg AND lactate >2 mmol/L despite fluids 1
6. If platelets <150,000: Calculate SIC score to identify coagulopathy 7, 1

Key Pitfall to Avoid

SIRS criteria are obsolete—do not use them for sepsis diagnosis. 1 SIRS has significantly worse discrimination (AUROC 0.65) compared to SOFA and misses many high-risk patients while over-identifying low-risk ones. 2, 5