qSOFA vs Sepsis Criteria: Differences and Clinical Applications
The quick Sequential Organ Failure Assessment (qSOFA) is a bedside screening tool to identify patients at risk of sepsis, while sepsis criteria (Sepsis-3) define sepsis as life-threatening organ dysfunction caused by a dysregulated host response to infection, characterized by an increase in the SOFA score of 2 points or more.
Definitions and Components
qSOFA
- A bedside screening tool used to identify patients with suspected infection who are at risk of developing sepsis outside of the ICU 1
- Includes three clinical parameters:
- Altered mental status
- Systolic blood pressure ≤100 mmHg
- Respiratory rate >22/min
- Score ≥2 indicates high risk of poor outcomes 1
- Designed for rapid assessment in non-ICU settings
SOFA Score (Full)
- Evaluates six organ systems: respiratory, cardiovascular, hepatic, coagulation, renal, and neurological
- Maximum score of 24 points
- An increase of ≥2 points indicates organ dysfunction associated with sepsis 1
Sepsis-3 Definition
- Sepsis is defined as life-threatening organ dysfunction caused by a dysregulated host response to infection 2, 1
- Organ dysfunction is identified as an acute increase in the SOFA score of ≥2 points
- Represents a significant evolution from previous definitions that relied on SIRS criteria
Performance and Clinical Utility
Sensitivity and Specificity
- qSOFA has lower sensitivity (31-36%) but higher specificity (78-90%) for detecting sepsis 3, 4
- SIRS criteria have higher sensitivity (58-68%) but lower specificity for sepsis detection 3, 5
- NEWS (National Early Warning Score) outperforms qSOFA with sensitivity of 86% vs 34% for sepsis detection 6
Predictive Value for Outcomes
- qSOFA demonstrates better discrimination for in-hospital mortality (AUC 0.74-0.85) compared to SIRS criteria (AUC 0.59-0.83) 5, 4
- qSOFA is a stronger independent predictor of hospital mortality with adjusted OR of 13.92 compared to sepsis with OR of 3.85 4
- qSOFA performs better than SIRS for predicting ICU-free days but may be less effective for predicting ventilator-free days and organ dysfunction-free days 5
Clinical Application Algorithm
Initial Assessment:
- Apply qSOFA in non-ICU settings (emergency department, wards, pre-hospital)
- Calculate SOFA score when laboratory results are available
Risk Stratification Based on qSOFA:
- qSOFA ≥2: High risk - initiate sepsis workup and treatment within 1 hour 1
- qSOFA <2 but clinical suspicion remains: Calculate full SOFA score when possible
Management Based on Risk Level:
- High-risk patients (qSOFA ≥2 or NEWS ≥7): Administer broad-spectrum antibiotics within 1 hour, IV fluid bolus (30 ml/kg crystalloid) for hypotension, monitor every 30 minutes 1
- Moderate-risk patients (NEWS 5-6): Administer antibiotics within 3 hours, IV fluids as needed, monitor hourly 1
- Low-risk patients (NEWS 1-4): Administer antibiotics within 6 hours, monitor every 4-6 hours 1
Important Considerations and Pitfalls
- qSOFA was designed as a risk stratification tool, not as a diagnostic test for sepsis 1
- The sensitivity of qSOFA is suboptimal (30-36%) for sepsis detection, potentially missing many cases 3, 6
- Patients with qSOFA ≥2 but not meeting sepsis criteria still have high mortality (22.2%) 4
- Patients meeting sepsis criteria but with qSOFA <2 have moderate mortality risk (7.3%) 4
- Time to sepsis detection was 16 minutes shorter with qSOFA compared to SIRS criteria 7
- Consider using NEWS ≥5 as an alternative screening tool with higher sensitivity (86%) for sepsis detection 6
Conclusion
qSOFA is a quick bedside tool for risk stratification with high specificity but limited sensitivity, while sepsis criteria (using SOFA score) provide a more comprehensive assessment of organ dysfunction but require laboratory values. The optimal approach is to use qSOFA for rapid screening and risk stratification, followed by full SOFA score calculation when laboratory results become available to confirm sepsis diagnosis.