NICE Guidance on Diagnosis of Sepsis
I must clarify that the evidence provided does not contain actual NICE (National Institute for Health and Care Excellence) guidelines—instead, the available evidence consists of international consensus guidelines from the Surviving Sepsis Campaign, Society of Critical Care Medicine, and other international bodies.
Primary Diagnostic Approach: SOFA Score-Based Criteria
The most current diagnostic standard defines sepsis as documented or suspected infection plus life-threatening organ dysfunction, indicated by an increase in Sequential Organ Failure Assessment (SOFA) score of ≥2 points, which correlates with in-hospital mortality >10%. 1
Core Diagnostic Criteria
The SOFA score evaluates six organ systems to identify sepsis-related organ dysfunction 1:
- Respiratory: PaO₂/FiO₂ ratio <300 or SpO₂ ≤90% 1
- Cardiovascular: Hypotension (SBP <90 mmHg or MAP <70 mmHg) or vasopressor requirement 1
- Renal: Creatinine >2.0 mg/dL (176.8 μmol/L) or urine output <0.5 mL/kg/h for ≥2 hours 1
- Hepatic: Bilirubin >2 mg/dL (34.2 μmol/L) 1
- Coagulation: Platelets <100,000/μL or INR >1.5 1
- Neurological: Altered mental status or decreased Glasgow Coma Scale 1
Alternative Diagnostic Framework: Surviving Sepsis Campaign Criteria
When SOFA scoring is impractical, the Surviving Sepsis Campaign provides broader diagnostic criteria requiring documented or suspected infection plus any of the following 2:
General Parameters
- Fever (>38.3°C) or hypothermia (<36°C) 2
- Heart rate >90/min or >2 SD above normal for age 2
- Tachypnea 2
- Altered mental status 2
- Significant edema or positive fluid balance (>20 mL/kg over 24h) 2
- Hyperglycemia (>140 mg/dL or 7.7 mmol/L) without diabetes 2
Inflammatory Parameters
- Leukocytosis (WBC >12,000/μL) or leukopenia (WBC <4,000/μL) 2
- Normal WBC with >10% immature forms (bandemia) 2
- Elevated C-reactive protein or procalcitonin (>2 SD above normal) 2
Tissue Perfusion Parameters
Severe Sepsis Definition
Severe sepsis is diagnosed when sepsis is accompanied by sepsis-induced tissue hypoperfusion or organ dysfunction 2, including:
- Sepsis-induced hypotension 2
- Lactate above upper limits of normal 2
- Urine output <0.5 mL/kg/h for >2 hours despite adequate fluid resuscitation 2
- Acute lung injury with PaO₂/FiO₂ <250 (without pneumonia) or <200 (with pneumonia) 2
- Creatinine >2.0 mg/dL (176.8 μmol/L) 2
- Bilirubin >2 mg/dL (34.2 μmol/L) 2
- Platelet count <100,000/μL 2
- Coagulopathy (INR >1.5) 2
Septic Shock Definition
Septic shock is defined as sepsis-induced arterial hypotension persisting despite adequate fluid resuscitation 2, with signs of tissue hypoperfusion present even when patients are on vasopressors 2.
Initial Risk Stratification
The National Early Warning Score 2 (NEWS2) is recommended for initial sepsis risk assessment, with scores ranging from 0 (very low risk) to ≥7 (high risk) 1.
Pediatric Diagnostic Modifications
In children, sepsis requires signs of inflammation plus infection with 2:
- Hyper- or hypothermia (rectal temperature >38.5°C or <35°C) 2
- Tachycardia (may be absent in hypothermia) 2
- At least one of: altered mental status, hypoxemia, increased lactate, or bounding pulses 2
Critical Clinical Caveat
A major pitfall is relying on a single diagnostic system—SIRS criteria identify sepsis earlier (median 26 minutes post-ED presentation) in >50% of patients, while SOFA criteria identify a distinct population later (median 113 minutes) 3. Using SOFA alone may delay identification, while using SIRS alone may miss sepsis presenting as acute organ dysfunction 3. Therefore, combining inflammatory (SIRS) and organ dysfunction (SOFA) criteria enhances timely identification 3.
Biomarker Considerations
Biomarkers such as procalcitonin, C-reactive protein, and lactate may assist evaluation but should not be used in isolation to exclude sepsis 4.