qSOFA Score

The quick Sequential Organ Failure Assessment (qSOFA) is a bedside screening tool designed to rapidly identify patients outside the ICU who are at risk for poor outcomes from suspected infection. Introduced as part of the Sepsis-3 consensus definitions published by Singer et al. in JAMA 2016, qSOFA was developed to address the need for a simple, rapid clinical assessment that does not require laboratory tests.

qSOFA evaluates three clinical criteria: systolic blood pressure of 100 mmHg or less, respiratory rate of 22 breaths per minute or higher, and altered mental status (any Glasgow Coma Scale score less than 15). Each criterion present scores one point, yielding a total of 0-3. A qSOFA score of 2 or more is considered positive and identifies patients at significantly higher risk of poor outcomes.

The significance of qSOFA lies in its simplicity and bedside applicability. Unlike the full SOFA score, which requires laboratory values (PaO2, platelets, bilirubin, creatinine) and knowledge of vasopressor dosing, qSOFA uses only physical examination findings available within seconds at the bedside. This makes it suitable for emergency departments, general medical wards, and prehospital settings.

In the Sepsis-3 framework, qSOFA serves as a screening trigger, not a diagnostic criterion. A positive qSOFA in a patient with suspected infection should prompt evaluation for organ dysfunction using the full SOFA score. The Sepsis-3 definition of sepsis itself requires an acute SOFA increase of 2 or more points, not merely a positive qSOFA.

The predictive validity of qSOFA varies by clinical setting. In general ward and emergency department settings, qSOFA has demonstrated good predictive validity for in-hospital mortality, with a positive score associated with 3-14 fold increased risk of death. However, sensitivity for identifying sepsis is moderate (approximately 50-70%), meaning a negative qSOFA does not rule out sepsis, and clinical suspicion should always drive the evaluation.

The three qSOFA criteria reflect fundamental physiological domains. Hypotension (SBP 100 or less) indicates cardiovascular compromise. Tachypnea (RR 22 or more) reflects respiratory compensation for metabolic derangement or primary respiratory pathology. Altered mental status indicates neurological dysfunction from inadequate cerebral perfusion, metabolic encephalopathy, or direct CNS involvement.

Controversies surrounding qSOFA include its limited sensitivity compared to prior SIRS criteria, potential for delayed identification of sepsis in patients not meeting the threshold, and variation in performance across different patient populations. Some experts advocate using qSOFA alongside (not instead of) SIRS criteria and clinical gestalt.

This calculator implements the three-criterion qSOFA scoring system with risk stratification, serving as a rapid screening tool for infection-related organ dysfunction outside the ICU.