What are the current criteria for diagnosing sepsis using the Sequential Organ Failure Assessment (SOFA) score and quick Sequential Organ Failure Assessment (qSOFA)?

Sepsis Diagnostic Criteria

Sepsis is diagnosed when a patient with suspected or confirmed infection has an acute increase in Sequential Organ Failure Assessment (SOFA) score of ≥2 points from baseline, which correlates with in-hospital mortality >10%. 1, 2, 3

Core Definitions

• Sepsis: Life-threatening organ dysfunction caused by a dysregulated host response to infection, operationalized as SOFA score increase ≥2 points 1, 2, 3
• Septic Shock: Subset of sepsis requiring vasopressors to maintain MAP ≥65 mmHg AND serum lactate >2 mmol/L despite adequate fluid resuscitation, with mortality >40% 1, 3
• "Severe sepsis" is obsolete and should not be used 1, 2

SOFA Score Components (0-4 points each system)

The full SOFA assesses six organ systems: 1

Respiratory

• 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 1

Cardiovascular

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

Hepatic

• Bilirubin >1.2 mg/dL scores points 1

Coagulation

• Platelet count <150,000/μL scores points 1

Renal

• Creatinine >3.5 mg/dL or urine output <500 mL/day scores maximum points 1

Neurological

• Glasgow Coma Scale assessment 1

Quick SOFA (qSOFA) for Bedside Screening

qSOFA ≥2 identifies high-risk patients requiring immediate full SOFA assessment and ICU-level care consideration. 1, 2, 4

Three Simple Criteria (1 point each):

• Respiratory rate ≥22 breaths/min 1, 4, 3
• Systolic blood pressure ≤100 mmHg 1, 4, 3
• Altered mental status (Glasgow Coma Scale <15) 1, 3

Critical Limitations of qSOFA:

• High specificity (96.1%) but poor sensitivity (29.7%) for organ dysfunction 5
• qSOFA should not be used as the sole screening tool due to low sensitivity and delayed identification 1
• NICE 2024 guidelines have formally discontinued qSOFA as the primary screening tool, adopting NEWS2 instead for emergency and acute-care settings 1

Alternative Screening: NEWS2 (NICE 2024 Recommendation)

NICE 2024 recommends NEWS2 over qSOFA for initial bedside risk stratification in emergency department and acute-care settings. 1

NEWS2 Risk Categories and Actions:

Score	Risk Level	Re-assessment Interval	Antibiotic Timing
≥7	High	Every 30 minutes	Within 1 hour
5-6	Moderate	Every 1 hour	Within 3 hours
1-4	Low	Every 4-6 hours	Within 6 hours
0	Very low	Standard monitoring	As clinically indicated

1

NEWS2 Override Criteria (Immediate Escalation):

• Any single NEWS2 parameter scoring 3 points 1
• Presence of purpuric rash (non-blanching petechial/purpuric skin lesion) regardless of calculated score 1
• Clinical deterioration despite interventions 1

Diagnostic Algorithm

Step 1: Identify Suspected Infection

• Calculate NEWS2 immediately in emergency/acute-care settings 1
• Or calculate qSOFA at bedside if NEWS2 unavailable 1, 2

Step 2: Risk Stratification

• If NEWS2 ≥7 or qSOFA ≥2: High-risk patient requiring immediate action 1
• Administer broad-spectrum IV antibiotics within 1 hour 1, 2
• Proceed immediately to full SOFA calculation 1, 2

Step 3: Calculate Full SOFA Score

• SOFA increase ≥2 points from baseline = Sepsis diagnosis 1, 2, 3
• Baseline SOFA assumed to be zero if no pre-existing organ dysfunction 3
• SOFA >11 predicts 100% sensitivity for sepsis and mortality >80-90% 1, 6

Step 4: Assess for Septic Shock

• Check if vasopressors needed for MAP ≥65 mmHg 1, 3
• Measure serum lactate (>2 mmol/L confirms shock if on vasopressors) 1, 3

Step 5: Serial Monitoring

• Re-calculate SOFA every 48-72 hours to track organ dysfunction trajectory 1, 2
• Worsening scores indicate poor prognosis and need for intervention escalation 1, 2

Important Caveats

• SIRS criteria are no longer required for sepsis diagnosis and have been removed from the definition 2, 3
• SOFA score demonstrates superior discriminative ability (AUC 0.89-0.96) compared to qSOFA or SIRS for predicting mortality 6, 7
• qSOFA was designed for rapid bedside screening, not definitive diagnosis 2, 4
• Full SOFA requires laboratory data and is not suitable for rapid initial screening 1
• In resource-limited or mass casualty settings, SOFA >10-11 may inform triage decisions given mortality >80-90% 1