Background and purpose
Sepsis is life-threatening organ dysfunction caused by a dysregulated host response to infection. The Sepsis-3 definitions emphasized measurable organ dysfunction, often operationalized with the Sequential Organ Failure Assessment (SOFA) score. Because SOFA incorporates multiple laboratory and clinical variables, it can be cumbersome at the bedside outside intensive care settings.
The quick SOFA (qSOFA) score was introduced as a simple, bedside screening tool based on three readily available findings: altered mentation, tachypnea, and hypotension. It is not equivalent to SOFA and does not, by itself, diagnose sepsis. Its primary role is to identify patients with suspected infection who may be at higher risk of poor outcomes and who merit prompt reassessment, monitoring, and further evaluation for organ dysfunction.
Components of the qSOFA score
qSOFA assigns one point per criterion, for a total score from 0 to 3. All three domains reflect acute physiological stress that may accompany infection and evolving illness severity.
Altered mentation (Glasgow Coma Scale < 15)
Central nervous system dysfunction can manifest as confusion, agitation, somnolence, or reduced responsiveness. The Sepsis-3 operationalization uses a threshold of GCS below 15 rather than relying solely on subjective terms such as “altered mental status,” which can vary between observers.
Clinicians should interpret GCS in context: pre-existing cognitive impairment, sedating medications, intoxication, metabolic encephalopathy, stroke, and primary neurological emergencies can lower GCS without sepsis. Conversely, early sepsis may present with subtle cognitive changes before other signs are obvious, so repeat assessment and correlation with the overall clinical picture remain essential.
Respiratory rate ≥ 22 breaths per minute
Tachypnea reflects increased ventilatory drive from tissue hypoperfusion, metabolic acidosis, hypoxemia, pain, anxiety, or primary pulmonary pathology. A threshold of 22 breaths per minute or higher was chosen as a simple, measurable criterion that often tracks with illness severity in infected patients.
Accurate measurement matters: counts should reflect true respiratory rate rather than artifact from monitoring or intermittent observation. Chronic lung disease, pulmonary embolism, heart failure exacerbations, and many non-infectious conditions can also elevate respiratory rate, which is why qSOFA is interpreted primarily when infection is suspected.
Systolic blood pressure ≤ 100 mmHg
Hypotension may indicate reduced vascular tone, hypovolemia, cardiac dysfunction, or sepsis-related circulatory compromise. qSOFA uses a single systolic threshold of 100 mmHg or lower as a practical bedside marker of hemodynamic stress.
Baseline hypertension may mask relative hypotension: a “normal” systolic pressure may still represent a significant drop for an individual who is usually hypertensive. Conversely, chronic hypotension, autonomic failure, or medication effects can produce low systolic blood pressure without acute infection. Clinical context, trends, perfusion assessment, and adjuncts such as lactate can help differentiate these scenarios.
How to calculate qSOFA
At the bedside, obtain the most reliable recent values and apply the criteria below. Each positive criterion contributes one point.
| Domain | Criterion (1 point if present) |
|---|---|
| Altered mentation | Glasgow Coma Scale < 15 |
| Respiratory | Respiratory rate ≥ 22 / min |
| Circulation | Systolic blood pressure ≤ 100 mmHg |
Total score = sum of points (0–3).
Interpreting the score in clinical practice
qSOFA performs best as a screening adjunct when there is suspected or known infection. It should be integrated with history, examination, focused diagnostics, and institutional protocols—not used as an isolated rule-in or rule-out test.
Score of 0
A score of 0 indicates that none of the three bedside criteria are met at that moment. This does not exclude serious infection, early sepsis, or a need for treatment. Patients can have significant organ dysfunction that is not captured by qSOFA, or may deteriorate rapidly. Repeat vital signs, monitoring appropriate to the setting, and further testing remain important whenever clinical suspicion persists.
Score of 1
A single positive criterion represents an intermediate signal. Depending on the clinical scenario, this may warrant closer observation, repeat assessments, laboratory evaluation (including lactate when indicated), and consideration of source control and antimicrobial therapy guided by infection likelihood and severity. Many non-septic conditions can produce any one individual criterion, so context determines urgency.
Score of 2 or 3
Two or three points are associated with a higher risk of poor outcomes among patients with suspected infection in the populations studied for screening performance. This should prompt escalation of care commensurate with severity: more frequent monitoring, early laboratory assessment, evaluation for shock, consideration of broad-spectrum antibiotics when sepsis is suspected, fluid resuscitation when appropriate, and involvement of higher-acuity services when indicated by institutional pathways.
Even with a high qSOFA, management decisions should still be individualized. The score summarizes three bedside variables; it does not replace assessment of end-organ perfusion, acid-base status, renal and hepatic function, coagulation, or the need for vasopressors and mechanical ventilation.
Relationship to SOFA and the Sepsis-3 framework
In the Sepsis-3 conceptual model, sepsis reflects infection complicated by organ dysfunction, commonly reflected by an increase in SOFA of 2 points or more (using baseline or an appropriate reference). Septic shock implies profound circulatory and metabolic abnormalities despite volume resuscitation, including hypotension requiring vasopressors and/or persistent hyperlactatemia, as defined in contemporary criteria.
qSOFA is not a substitute for SOFA. A patient may have a low qSOFA yet meet sepsis criteria based on laboratory and clinical organ dysfunction. Conversely, a patient may have a high qSOFA due to acute physiological derangement without meeting formal sepsis definitions if infection is not present or organ dysfunction criteria are not fulfilled. In practice, clinicians often use qSOFA as a prompt to calculate SOFA, measure lactate, obtain cultures, and implement sepsis bundles when appropriate.
Settings and workflow considerations
qSOFA was designed with simplicity in mind and is frequently discussed in emergency departments, general wards, and other environments where full SOFA inputs may not be immediately available. In critically ill patients who already have comprehensive monitoring, SOFA or other ICU scores may be more informative for tracking organ dysfunction over time.
Effective use typically includes:
- Identifying suspected infection early and defining the likely source
- Applying qSOFA as a rapid screen alongside clinical gestalt
- Trending vitals and mental status, not relying on a single snapshot
- Escalating diagnostics and therapy according to response and local sepsis pathways
- Reassessing after interventions (fluids, antibiotics, source control)
Limitations and pitfalls
qSOFA has important constraints that affect interpretation:
- Diagnostic accuracy varies by population, baseline comorbidities, and care setting; no score replaces bedside judgment.
- Sensitivity and specificity trade-offs mean both false reassurance and false alarms are possible.
- It omits key variables such as lactate, urine output, oxygenation beyond respiratory rate, and detailed cardiovascular support needs.
- Medications and devices (beta-blockers, sedatives, spinal cord injury, non-invasive ventilation) can alter vitals and GCS independent of sepsis.
- Language, developmental, and cognitive factors can complicate GCS assessment.
- Scores are time-dependent; deterioration can occur quickly, so repeat evaluation is critical.
qSOFA is an educational and decision-support adjunct. It does not establish a diagnosis, determine antimicrobial choice, or replace specialist consultation, institutional protocols, or applicable laws and regulations governing medical practice.