What are the diagnosis and management strategies for sepsis, particularly in relation to the Sequential Organ Failure Assessment (SOFA) score?

Sepsis Diagnosis and Management Using SOFA Score

Definition and Diagnostic Criteria

Sepsis is diagnosed when a patient with suspected or confirmed infection has an acute increase in SOFA score of ≥2 points, which correlates with in-hospital mortality exceeding 10%. 1

• The SOFA score assesses six organ systems (respiratory, cardiovascular, hepatic, coagulation, renal, and neurological), with each system scored 0-4 points based on severity of dysfunction. 1
• A baseline SOFA score of 0 should be assumed in patients without pre-existing organ dysfunction. 1
• The concept of "severe sepsis" is obsolete and should not be used in clinical practice. 1

SOFA Score Components and Calculation

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

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

Other Systems

• Hepatic: Bilirubin levels (>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

Clinical Implementation Algorithm

Step 1: Initial Bedside Screening

• Calculate quick SOFA (qSOFA) at bedside for any patient with suspected infection. 1
• qSOFA criteria (1 point each): respiratory rate ≥22/min, systolic blood pressure ≤100 mmHg, altered mental status (GCS <15). 1
• If qSOFA ≥2: Immediately proceed to full SOFA assessment, as this indicates >10% mortality risk. 1

Step 2: Full SOFA Score Calculation

• Calculate complete SOFA score using all six organ system parameters. 1
• Sepsis is confirmed when SOFA increases ≥2 points from baseline in the setting of infection. 1
• A SOFA score >11 has 100% sensitivity and negative predictive value for sepsis diagnosis. 2

Step 3: Septic Shock Assessment

• Septic shock is identified by: vasopressor requirement to maintain MAP ≥65 mmHg AND serum lactate >2 mmol/L (>18 mg/dL) despite adequate fluid resuscitation. 1, 3
• This combination indicates profound circulatory, cellular, and metabolic abnormalities with significantly higher mortality. 3

Alternative Risk Stratification: NEWS2 Score

For emergency department settings, the 2024 NICE guidelines recommend using NEWS2 for initial risk stratification:

NEWS2 Score Interpretation

• Score 0: Very low risk of severe illness or death from sepsis. 4
• Score 1-4: Low risk of severe illness or death from sepsis. 4
• Score 5-6: Moderate risk of severe illness or death from sepsis. 4
• Score ≥7: High risk of severe illness or death from sepsis. 4

Critical Single Parameters

• A score of 3 in any single NEWS2 parameter may indicate increased sepsis risk regardless of total score. 4
• Consider higher risk than NEWS2 suggests if: mottled/ashen appearance, non-blanching petechial/purpuric rash, or cyanosis present. 4

Monitoring Frequency Based on Risk

High Risk (NEWS2 ≥7 or SOFA increase ≥2)

• Re-calculate NEWS2 and re-evaluate every 30 minutes. 4
• Serial SOFA scores should be measured every 48-72 hours to track organ dysfunction trajectory. 1

Moderate Risk (NEWS2 5-6)

• Re-evaluate every hour. 4

Low Risk (NEWS2 1-4)

• Re-evaluate every 4-6 hours. 4

Antibiotic Timing Based on Risk Stratification

The 2024 NICE guidelines provide specific antibiotic administration timeframes:

• High risk patients (NEWS2 ≥7): Administer antibiotics within 1 hour of risk assessment. 4
• Moderate risk patients (NEWS2 5-6): Administer antibiotics within 3 hours. 4
• Low risk patients (NEWS2 1-4): Administer antibiotics within 6 hours. 4

These timeframes represent maximum times until prescription, not targets to work toward, and promote antimicrobial stewardship while reducing potential antibiotic-related harm. 4

Prognostic Value and Serial Monitoring

Single Time Point Assessment

• SOFA score at admission has an AUC of 0.75 for predicting in-hospital mortality. 5
• SOFA score at 72 hours post-ICU admission has improved AUC of 0.84 for mortality prediction. 5
• LODS score performs similarly to SOFA (28-day AUC 0.668 vs 0.661), while qSOFA has significantly lower accuracy (AUC 0.558). 6

Serial SOFA Measurements

• Mean SOFA score (calculated from serial measurements) has superior predictive value with sensitivity of 93.65% and specificity of 100% for mortality prediction. 7
• Delta SOFA (change from admission to 72 hours) has a positive linear relationship with in-hospital mortality. 5
• Worsening serial SOFA scores indicate poor prognosis and need for escalation of interventions. 1

Special Consideration: Sepsis-Induced Coagulopathy (SIC)

For patients with thrombocytopenia, calculate the SIC score:

SIC Score Components

• Platelet count scoring
• PT ratio scoring
• SOFA score component 4, 1

Clinical Significance

• SIC score ≥4 identifies coagulopathy requiring specific interventions. 1
• SIC-positive patients have mortality of 32.5-37.2%. 4
• SIC shows 95.7% negative predictive value for overt disseminated intravascular coagulation (DIC). 1
• SIC precedes overt DIC and allows earlier detection of coagulopathy. 4

Critical Pitfalls to Avoid

• Do not delay full SOFA assessment when qSOFA ≥2, as this identifies high-risk patients requiring immediate intensive intervention. 1
• Do not use qSOFA alone for diagnosis—it is a screening tool only; full SOFA score is required for sepsis diagnosis. 2, 6
• Do not fail to measure lactate levels, as they are essential for identifying septic shock. 3
• Do not interpret SOFA scores in isolation—consider underlying physiology, comorbidities, and clinical trajectory. 4
• Do not continue excessive fluid administration while delaying vasopressor initiation in septic shock. 3
• In mass casualty or resource-limited settings, SOFA scores >10-11 predict mortality >80-90% and may inform difficult triage decisions. 1