What are the current Sepsis‑3 criteria for diagnosing sepsis and septic shock, including the use of the Sequential Organ Failure Assessment (SOFA) score and quick SOFA (qSOFA)?

Sepsis-3 Diagnostic Criteria

Sepsis is defined as life-threatening organ dysfunction caused by a dysregulated host response to infection, operationalized as an acute increase in the Sequential Organ Failure Assessment (SOFA) score of ≥2 points from baseline, which correlates with in-hospital mortality >10%. 1, 2

Core Diagnostic Framework

SOFA Score Components (0-4 points each system)

The full SOFA score assesses six organ systems: 1

Respiratory System:

• 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 System:

• 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 System:

• Bilirubin >1.2 mg/dL scores points on SOFA 1

Coagulation System:

• Platelets <150,000/μL scores points 1

Renal System:

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

Neurological System:

• Glasgow Coma Scale assessment (lower scores = more points) 1

Septic Shock Criteria

Septic shock is identified by the simultaneous presence of: 1, 2

• Vasopressor requirement to maintain MAP ≥65 mmHg AND
• Serum lactate >2 mmol/L (>18 mg/dL)
• Despite adequate fluid resuscitation

This combination is associated with hospital mortality rates >40%. 2

Quick SOFA (qSOFA) for Bedside Screening

When to Use qSOFA

qSOFA is recommended for rapid bedside identification of high-risk patients with suspected infection in non-ICU settings, NOT as a definitive diagnostic tool. 1, 3 The Surviving Sepsis Campaign 2021 explicitly recommends against using qSOFA as a single screening tool due to insufficient sensitivity (28-42%). 3

qSOFA Criteria (1 point each)

A score ≥2 indicates high risk: 1, 4, 2

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

qSOFA Performance Characteristics

Critical limitation: qSOFA has only 16-52% sensitivity for identifying severe sepsis/septic shock, but 86-97% specificity. 5, 6 This means qSOFA misses many septic patients but rarely misidentifies non-septic patients. 5

Best use: Prognostication rather than screening—patients with qSOFA ≥2 have >10% mortality risk and increased likelihood of ICU admission ≥3 days. 3

Clinical Implementation Algorithm

Step 1: Initial Bedside Assessment

• For any patient with suspected infection, calculate qSOFA immediately 1
• If qSOFA ≥2: proceed immediately to full SOFA assessment 1
• Alternative (preferred in UK/Europe): Use NEWS2 score for initial screening, which has 84-86% sensitivity versus qSOFA's 28-42% 3

Step 2: Full SOFA Calculation

• Calculate baseline SOFA score (or assume 0 if unknown) 2
• Calculate current SOFA score across all six organ systems 1
• Sepsis is diagnosed if SOFA increases ≥2 points 1, 2

Step 3: Assess for Septic Shock

• Check if patient requires vasopressors to maintain MAP ≥65 mmHg 1
• Measure serum lactate 1
• Septic shock confirmed if both: vasopressors needed AND lactate >2 mmol/L 1, 2

Step 4: Risk-Based Monitoring

For patients with qSOFA ≥2 or SOFA increase ≥2: 1

• Re-calculate scores every 30 minutes initially
• Transfer to ICU-level care 1
• Administer broad-spectrum IV antibiotics within 1 hour 1

Important Caveats and Pitfalls

The term "severe sepsis" is obsolete and should not be used—all sepsis by definition involves organ dysfunction. 1, 2

qSOFA limitations in prehospital/early ED settings: The dynamic nature of sepsis means many patients do not yet meet qSOFA thresholds early in presentation, particularly for systolic blood pressure and respiratory rate. 5 Failure to meet qSOFA criteria does not exclude sepsis.

SOFA score limitations: Some components (PaO₂/FiO₂ ratio, specific vasopressor doses) are not routinely recorded in all electronic health records, limiting utility for automated surveillance. 7 The CDC Adult Sepsis Event uses simplified eSOFA criteria that identify a smaller but more severely ill cohort (17.1% mortality vs 14.4% with full SOFA). 7

Baseline SOFA considerations: Assume baseline SOFA = 0 if unknown, but recognize that patients with chronic organ dysfunction may have elevated baseline scores. 2

Special Consideration: Sepsis-Induced Coagulopathy (SIC)

For patients with sepsis and thrombocytopenia, calculate the SIC score: 8, 1

• Platelet count scoring
• PT-INR scoring
• SOFA score (limited to 2 points maximum even if actual SOFA >2)

SIC score ≥4 identifies coagulopathy requiring specific interventions, with mortality 32.5-37.2% and 95.7% negative predictive value for overt DIC. 1