詳細ガイド 近日公開
qSOFA Score (Sepsis)の包括的な教育ガイドを準備中です。ステップバイステップの解説、数式、実例、専門家のヒントをお届けしますので、もうしばらくお待ちください。
The Quick Sequential Organ Failure Assessment (qSOFA) score is a rapid bedside clinical scoring tool used to identify adult patients outside the intensive care unit (ICU) who are at high risk of poor outcomes — including in-hospital mortality and prolonged ICU stay — when suspected of having an infection. It was introduced as part of the landmark Sepsis-3 consensus definitions published by Seymour, Liu, Iwashyna, and colleagues in JAMA in February 2016. qSOFA was designed in response to the clinical need for a simple, immediately calculable, no-laboratory-test-required screening tool that could flag deteriorating septic patients in emergency departments, general wards, and community settings. Unlike the full SOFA (Sequential Organ Failure Assessment) score, which requires blood tests including creatinine, bilirubin, platelet count, PaO₂/FiO₂ ratio, and vasopressor doses, qSOFA uses only three clinical observations that can be made at the bedside in under one minute. The three criteria are: (1) altered mental status, defined as a Glasgow Coma Scale score below 15 (new confusion, drowsiness, or agitation); (2) respiratory rate of 22 breaths per minute or greater; and (3) systolic blood pressure of 100 mmHg or less. Each criterion scores one point, giving a total range of 0 to 3. A score of 2 or 3 identifies patients with a significantly increased risk of in-hospital death or prolonged ICU admission — the original derivation cohort showed in-hospital mortality exceeding 10% at qSOFA ≥ 2 compared with under 1% at qSOFA 0. Importantly, qSOFA is a screening and prognostication tool — it is not a diagnostic tool for sepsis itself (which requires confirmed or suspected infection plus organ dysfunction defined by a SOFA score increase ≥ 2). A positive qSOFA should prompt urgent assessment, escalation to senior clinicians, blood cultures, lactate measurement, and initiation of the sepsis care bundle.
qSOFA Score = AMS + RR + SBP Where each criterion scores 0 (absent) or 1 (present): 1. Altered Mental Status (AMS) Present (1 pt): GCS < 15 (any new confusion, disorientation, reduced responsiveness, or agitation) Absent (0 pt): GCS = 15 (fully alert and oriented) 2. Respiratory Rate (RR) Present (1 pt): RR ≥ 22 breaths/minute Absent (0 pt): RR < 22 breaths/minute 3. Systolic Blood Pressure (SBP) Present (1 pt): SBP ≤ 100 mmHg Absent (0 pt): SBP > 100 mmHg Total score range: 0–3 Score 0–1: Low risk outside ICU (in suspected infection) Score ≥ 2: High risk — significant mortality risk, urgent escalation required
- 1Assess the patient's conscious level: obtain a Glasgow Coma Scale score or rapidly assess using AVPU. Any GCS below 15 — including confusion (GCS 14), drowsiness (GCS 13 or lower), inability to recall the date or location, or agitation — scores 1 point. Critically, the question is whether this represents a NEW change from baseline, not a chronic cognitive impairment.
- 2Measure the respiratory rate by direct observation for a full 60 seconds (do not use monitor-derived respiratory rate as it is often inaccurate). A rate of 22 breaths per minute or more scores 1 point. Tachypnoea is one of the earliest signs of physiological compensation in sepsis and often precedes haemodynamic deterioration by hours.
- 3Measure systolic blood pressure using a calibrated sphygmomanometer or arterial line. A systolic BP of 100 mmHg or less scores 1 point. Note that hypotension this severe in the context of suspected infection may already represent septic shock territory (septic shock is formally defined as vasopressor requirement to maintain MAP ≥ 65 mmHg plus lactate > 2 mmol/L).
- 4Sum the three criteria to obtain the qSOFA score (0–3). A score of ≥ 2 in a patient with suspected or confirmed infection identifies high risk of poor outcome. This should trigger immediate escalation: notify senior clinician, obtain blood cultures (before antibiotics if possible without delay), measure serum lactate, initiate intravenous access and fluids, and apply your institution's sepsis care bundle (Sepsis-6 or Hour-1 bundle).
- 5Understand what qSOFA does NOT do: it does not diagnose sepsis (the Sepsis-3 definition requires SOFA ≥ 2), it does not replace clinical judgement in patients with a single criterion who appear clearly unwell, and it is not validated for ICU patients (who by definition already have or are at high risk of organ dysfunction — use full SOFA in ICU). A qSOFA score of 0 or 1 does not rule out sepsis.
- 6Apply the full SOFA score when ICU or high-dependency resources are being considered or when the patient is already in a monitored setting. Full SOFA requires: PaO₂/FiO₂ ratio, Glasgow Coma Scale, MAP and vasopressor dose, bilirubin, creatinine/urine output, and platelet count. A SOFA score ≥ 2 above baseline defines sepsis in the context of infection.
- 7Reassess qSOFA serially — as the patient's clinical status evolves (with or without treatment), the score will change. Improvement in qSOFA score with treatment provides useful real-time feedback on clinical response, while failure to improve or deterioration should prompt escalation of care, broadened antibiotic cover, and consideration of ICU transfer.
Immediate sepsis care bundle: cultures, lactate, IV antibiotics, fluid resuscitation
All three qSOFA criteria are met. In the context of suspected infection, this represents extremely high risk — the Sepsis-3 derivation study showed in-hospital mortality exceeding 24% at qSOFA score 3. Immediate escalation, blood cultures (two sets peripherally), serum lactate, broad-spectrum IV antibiotics within 1 hour, and 500 mL IV fluid bolus are all indicated. ICU consult if lactate > 2 mmol/L.
qSOFA 0 does not rule out sepsis — use clinical judgement and full assessment
A qSOFA of 0 indicates lower risk of poor outcome, but does not exclude clinically significant infection or early sepsis. This patient with fever and productive cough needs a full sepsis assessment including CXR, blood cultures, inflammatory markers (CRP, WBC, procalcitonin), and empirical antibiotics if pneumonia is confirmed. qSOFA sensitivity is approximately 70% — a third of septic patients with poor outcomes will have qSOFA < 2.
Threshold met — escalate, cultures, lactate, IV antibiotics
Two of three qSOFA criteria are met: tachypnoea and hypotension. The alert mental status (GCS 15) and fever complete a picture consistent with early septic shock from skin and soft tissue infection. The Sepsis Hour-1 bundle should be initiated: measure lactate, obtain blood cultures, administer broad-spectrum antibiotics covering streptococcal and staphylococcal organisms, crystalloid bolus 30 mL/kg if lactate > 4 or haemodynamically unstable. Reassess within 1 hour.
Use full SOFA in ICU; qSOFA designed for non-ICU settings only
qSOFA was derived and validated in patients presenting to emergency departments and general wards — not in ICU patients who are already by definition at high risk of organ dysfunction. For ICU patients, the full SOFA score (with PaO₂/FiO₂, GCS, vasopressors, bilirubin, creatinine, platelets) is the appropriate tool. A baseline and daily SOFA is standard in most ICUs.
Emergency department triage — rapid identification of patients with suspected infection at high risk of deterioration to direct immediate resuscitation efforts and prioritise senior review, where accurate qsofa analysis through the Qsofa supports evidence-based decision-making and quantitative rigor in professional workflows
General ward sepsis screening — nursing and junior medical staff applying qSOFA as part of routine NEWS2 assessment to trigger sepsis escalation protocols without waiting for laboratory results, where accurate qsofa analysis through the Qsofa supports evidence-based decision-making and quantitative rigor in professional workflows
Ambulance and pre-hospital settings — paramedics using qSOFA as a pre-arrival notification tool to prepare receiving emergency departments for incoming septic patients, where accurate qsofa analysis through the Qsofa supports evidence-based decision-making and quantitative rigor in professional workflows
Low-resource healthcare settings — primary care and district hospitals in LMICs where laboratory investigations are unavailable, using qSOFA to identify patients requiring urgent transfer to higher-level facilities, where accurate qsofa analysis through the Qsofa supports evidence-based decision-making and quantitative rigor in professional workflows
Clinical research and audit — qSOFA provides a standardised, reproducible definition for identifying high-risk sepsis patients in registry studies, quality improvement programmes, and sepsis mortality audits
qSOFA in paediatric patients
qSOFA was derived and validated exclusively in adult patients. Paediatric sepsis has different physiological parameters and vital sign thresholds — children compensate differently, often maintaining blood pressure until very late stages of shock while tachycardia and tachypnoea appear early. Paediatric sepsis screening uses age-specific SIRS criteria or paediatric-specific tools. Do not apply adult qSOFA thresholds to children under 18 years.
Altered mental status interpretation in patients with pre-existing dementia
The AMS criterion in qSOFA requires that the reduced GCS represents a NEW change from the patient's baseline. In patients with chronic dementia or other baseline cognitive impairment, GCS may be persistently below 15 without any acute deterioration. In these patients, assessment of acute-on-chronic confusion requires collateral history from carers or family. A patient with known GCS of 12 at baseline who remains GCS 12 does not score the AMS point; a patient with known GCS of 15 who is now GCS 13 does score it.
qSOFA and COVID-19
During the COVID-19 pandemic, qSOFA was prospectively studied in patients with SARS-CoV-2 infection. Studies showed variable performance — qSOFA performed reasonably for predicting in-hospital mortality in COVID-19 pneumonia, but some patients with severe hypoxaemia (low SpO₂) and imminent respiratory failure had qSOFA scores of 0 or 1 because their blood pressure was maintained and cognition was intact. The NEWS2 score (which includes SpO₂ and supplemental oxygen parameters) was found to be more sensitive in COVID-19 patients, leading to NHS guidance recommending NEWS2 over qSOFA for COVID-19 triage.
qSOFA in low-resource settings
One of the key design features of qSOFA is its applicability in resource-limited settings where laboratory investigations may not be available. The WHO Integrated Management of Adolescent and Adult Illness (IMAI) sepsis guidelines have incorporated qSOFA-like elements into bedside assessment checklists for use in district hospitals in low- and middle-income countries. For community health workers, even simpler screening (confusion + rapid breathing + low blood pressure) approximates the qSOFA construct and can identify patients needing urgent transfer.
Immunocompromised patients — qSOFA may underperform
Severely immunocompromised patients (neutropaenia, haematological malignancy, solid organ transplant recipients) may not mount the typical inflammatory response that drives tachypnoea and hypotension early in sepsis. Additionally, corticosteroid use can blunt fever. In these patients, qSOFA may be less sensitive as an early warning tool. Clinicians should have a lower threshold for blood cultures, broad-spectrum antibiotics, and full organ dysfunction assessment in immunocompromised patients with suspected infection regardless of qSOFA score.
| qSOFA Score | Risk Level | Estimated In-Hospital Mortality | Recommended Action |
|---|---|---|---|
| 0 | Low | < 1% | Continue monitoring; reassess if clinical status changes |
| 1 | Low-moderate | 1–3% | Lower risk by qSOFA alone; use clinical judgement; measure lactate if concerned |
| 2 | High | ~10–15% | Urgent sepsis assessment; initiate care bundle; escalate to senior clinician |
| 3 | Very high | ~20–25% | Emergency response; sepsis care bundle immediately; ICU consult; consider septic shock |
What does qSOFA stand for?
qSOFA stands for Quick Sequential Organ Failure Assessment. The 'quick' prefix distinguishes it from the full SOFA (Sequential Organ Failure Assessment) score which requires laboratory parameters. qSOFA was developed as a rapid bedside tool using only three clinical observations — altered mental status, respiratory rate ≥ 22/min, and systolic BP ≤ 100 mmHg — to screen for patients at high risk of poor outcomes in the context of suspected infection outside the ICU.
What score indicates high risk on qSOFA?
A qSOFA score of 2 or 3 out of a maximum of 3 is the threshold for high risk. In the Sepsis-3 derivation study (Seymour et al. JAMA 2016), a qSOFA ≥ 2 was associated with in-hospital mortality greater than 10% and a significantly increased risk of prolonged ICU stay (>3 days). A score of 0 or 1 indicates lower risk but does not rule out sepsis — clinical judgement remains essential.
What is the sensitivity and specificity of qSOFA?
In external validation studies, qSOFA ≥ 2 has a sensitivity of approximately 60–70% and specificity of approximately 80–83% for predicting in-hospital mortality in suspected infection outside ICU. The relatively low sensitivity means that up to 30–40% of patients who will die from sepsis may have a qSOFA < 2 at initial assessment — reinforcing that qSOFA is a screening and risk-stratification tool, not a diagnostic test, and must be used alongside clinical assessment.
How does qSOFA differ from full SOFA?
The full SOFA score assesses six organ systems: respiratory (PaO₂/FiO₂ ratio), neurological (GCS), cardiovascular (MAP and vasopressor requirement), hepatic (bilirubin), renal (creatinine and urine output), and haematological (platelet count). It requires laboratory results and arterial blood gas analysis and is designed for ICU use. qSOFA uses only three immediately available clinical parameters, requires no blood tests, and is designed for non-ICU settings as a rapid screening tool. SOFA ≥ 2 from baseline defines sepsis; qSOFA ≥ 2 indicates high risk warranting urgent assessment.
Is qSOFA better than SIRS for identifying sepsis?
The Sepsis-3 taskforce (2016) compared qSOFA and SIRS (systemic inflammatory response syndrome criteria: temperature, WBC, HR, RR) and found qSOFA had superior predictive validity for in-hospital mortality and ICU admission compared to SIRS in non-ICU patients with suspected infection. SIRS criteria are met by many non-infected, non-septic patients (high sensitivity but poor specificity), making qSOFA more discriminating. The Sepsis-3 definitions formally abandoned SIRS as the basis for sepsis diagnosis in favour of organ dysfunction (SOFA) criteria.
Can qSOFA be used in the ICU?
No — qSOFA was not derived or validated for use in ICU patients. ICU patients already have access to monitoring and laboratory investigations that enable full SOFA scoring, and by definition they are already in a high-acuity setting. The full SOFA score, assessed at baseline and serially, is the appropriate tool in the ICU to track organ dysfunction trajectory and identify sepsis (SOFA ≥ 2 from baseline in the context of infection). For ICU patients, qSOFA adds little discriminative value.
What is the sepsis Hour-1 bundle and how does qSOFA trigger it?
The Surviving Sepsis Campaign Hour-1 Bundle (2018) recommends that within the first hour of identifying high-risk sepsis, clinicians should: (1) measure lactate level (repeat if initial lactate >2 mmol/L); (2) obtain blood cultures before antibiotics; (3) administer broad-spectrum antibiotics; (4) begin rapid IV crystalloid administration (30 mL/kg) for hypotension or lactate ≥4 mmol/L; and (5) apply vasopressors if haemodynamically unstable. A qSOFA score ≥ 2 in a patient with suspected infection is a recognised trigger to initiate this bundle and escalate to senior clinical oversight.
What is the role of lactate measurement alongside qSOFA?
Serum lactate is a critical companion measurement to qSOFA. Elevated lactate (> 2 mmol/L) in the setting of suspected infection indicates tissue hypoperfusion (the hallmark of septic shock) even when blood pressure appears maintained — a condition called 'cryptic shock' or 'occult hypoperfusion'. A lactate > 4 mmol/L is a criterion for aggressive fluid resuscitation and vasopressor therapy. Because qSOFA does not assess lactate, a patient can have qSOFA = 1 but critically elevated lactate; therefore, lactate must be measured in all patients with suspected sepsis regardless of qSOFA score.
プロのヒント
Always combine qSOFA with a NEWS2 or equivalent early warning score assessment — the two tools are complementary. qSOFA specifically flags the high-risk infection patient, while NEWS2 provides continuous monitoring sensitivity. In any patient with qSOFA ≥ 2, measure serum lactate immediately: a lactate > 2 mmol/L (even with normal blood pressure) indicates tissue hypoperfusion and meets criteria for septic shock when combined with vasopressor requirement.
ご存知でしたか？
The Sepsis-3 paper introducing qSOFA (Seymour et al., JAMA 2016) was simultaneously published alongside two companion papers in the same issue — one deriving and validating the updated SOFA score definition of sepsis, and one redefining septic shock. Together, these three papers changed the global definition of sepsis for the first time since 1991 (Sepsis-1/Bone criteria) and removed SIRS from the definition. The study analysed over 1.3 million electronic health records from ICUs in the United States and Germany — one of the largest clinical data analyses ever used to derive a clinical score.
参考文献
- ›Seymour CW et al. Assessment of Clinical Criteria for Sepsis: For the Third International Consensus Definitions for Sepsis and Septic Shock (Sepsis-3) — JAMA 2016
- ›Singer M et al. The Third International Consensus Definitions for Sepsis and Septic Shock (Sepsis-3) — JAMA 2016
- ›Surviving Sepsis Campaign: International Guidelines for Management of Sepsis and Septic Shock 2021 — Critical Care Medicine 2021
- ›Freund Y et al. Prognostic Accuracy of Sepsis-3 Criteria for In-Hospital Mortality Among Patients With Suspected Infection Presenting to the Emergency Department — JAMA 2017
- ›National Institute for Health and Care Excellence (NICE). Sepsis: recognition, diagnosis and early management. Guideline NG51 — 2016, updated 2024