What are the current diagnostic criteria for sepsis in adults, including the Sequential Organ Failure Assessment (SOFA) and quick SOFA (qSOFA) thresholds?

Sepsis Diagnostic Criteria in Adults

Sepsis is defined as life-threatening organ dysfunction caused by a dysregulated host response to infection, operationalized as an acute increase in Sequential Organ Failure Assessment (SOFA) score of ≥2 points from baseline, which correlates with in-hospital mortality exceeding 10%. 1, 2, 3

Core Diagnostic Framework

SOFA Score Components (0-4 points per system, total 0-24)

The SOFA score assesses six organ systems to quantify organ dysfunction 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:

• Platelet count <150,000/μL contributes to scoring 1

Renal System:

• Creatinine >3.5 mg/dL or urine output <500 mL/day indicates severe dysfunction 1

Neurological System:

• Glasgow Coma Scale <15 indicates altered mental status 1

Quick SOFA (qSOFA) - Bedside Screening Tool

qSOFA consists of three simple bedside criteria, with ≥2 points indicating high-risk patients requiring immediate full SOFA assessment and predicting >10% mortality risk 1, 3:

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

Septic Shock Criteria

Septic shock is identified by the combination of vasopressor requirement to maintain MAP ≥65 mmHg AND serum lactate >2 mmol/L despite adequate fluid resuscitation, which is associated with hospital mortality rates >40%. 1, 2, 3

Clinical Implementation Algorithm

Step 1: Identify Suspected Infection

• Calculate qSOFA at bedside for any patient with suspected infection 1

Step 2: Risk Stratification

• If qSOFA ≥2: High-risk patient requiring immediate full SOFA assessment 1
• If qSOFA <2: Continue monitoring but lower immediate risk 1

Step 3: Calculate Full SOFA Score

• Determine baseline SOFA (use preadmission data when available) 5
• Calculate current SOFA score across all six organ systems 1
• Sepsis is diagnosed if SOFA increases ≥2 points from baseline 1, 3

Step 4: Assess for Septic Shock

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

Important Clinical Caveats

The term "severe sepsis" is obsolete and should not be used, as recommended by current consensus definitions 1. The previous hierarchical model suggesting sepsis progresses through "severe sepsis" to shock is misleading 3.

qSOFA has high specificity (96.1%) but poor sensitivity (29.7%) for organ dysfunction 6. This means qSOFA ≥2 reliably identifies high-risk patients, but qSOFA <2 does not exclude sepsis—full SOFA assessment remains necessary when clinical suspicion is high 7, 6.

SIRS criteria are no longer recommended for sepsis screening, though SIRS presence does correlate with increased risk of organ dysfunction (relative risk 3.5) and mortality 6. The excessive focus on inflammation in SIRS criteria led to inadequate specificity and sensitivity 3.

In patients with cirrhosis, Sepsis-3 criteria (AUROC=0.784) and qSOFA (AUROC=0.732) demonstrate significantly greater discrimination for in-hospital mortality than SIRS criteria (AUROC=0.606) 5. These patients require the same diagnostic approach but deserve more intensive surveillance when criteria are met 5.