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The SOFA (Sequential Organ Failure Assessment) score and its bedside screening cousin, qSOFA (quick SOFA), are the two clinical scoring tools that operationalize the current, consensus definition of sepsis. Since the 2016 Third International Consensus Definitions for Sepsis and Septic Shock — known as Sepsis-3 — a SOFA-based organ-dysfunction threshold, not a systemic-inflammation checklist, is what separates “infection” from “sepsis.” This page covers the six-organ-system SOFA table, the three-criteria qSOFA screen, how the two relate to each other and to septic shock, and why the distinction between a screening tool and a diagnostic threshold matters as much for research and quality reporting as it does at the bedside.
What the SOFA score measures
SOFA was originally developed as a way to track organ dysfunction over time in critically ill patients — not as a sepsis tool specifically — and it predates Sepsis-3 by two decades (Vincent JL et al., “The SOFA (Sepsis-related Organ Failure Assessment) score to describe organ dysfunction/failure,” Intensive Care Medicine, 1996). It assigns 0–4 points across six organ systems, using routinely available ICU data, for a total range of 0–24:
| Organ system | Measure | 0 pts | 1 pt | 2 pts | 3 pts | 4 pts |
|---|---|---|---|---|---|---|
| Respiratory | PaO₂/FiO₂ (mmHg) | ≥400 | <400 | <300 | <200 with respiratory support | <100 with respiratory support |
| Coagulation | Platelets (×10³/µL) | ≥150 | <150 | <100 | <50 | <20 |
| Hepatic | Bilirubin (mg/dL) | <1.2 | 1.2–1.9 | 2.0–5.9 | 6.0–11.9 | ≥12.0 |
| Cardiovascular | MAP or vasopressor dose | MAP ≥70 mmHg | MAP <70 mmHg | Dopamine <5 or dobutamine (any dose) | Dopamine 5.1–15, or epinephrine/norepinephrine ≤0.1 µg/kg/min | Dopamine >15, or epinephrine/norepinephrine >0.1 µg/kg/min |
| Central nervous system | Glasgow Coma Scale | 15 | 13–14 | 10–12 | 6–9 | <6 |
| Renal | Creatinine (mg/dL) or urine output | <1.2 | 1.2–1.9 | 2.0–3.4 | 3.5–4.9, or UOP <500 mL/day | ≥5.0, or UOP <200 mL/day |
Each system is scored independently and the six are summed; there is no weighting between systems. SOFA is designed to be tracked serially — the trend, not just a single snapshot, is what ICU teams use it for — and it requires arterial blood gas, coagulation, and chemistry values that are routinely drawn in critical care but not necessarily on a general ward, which is the practical reason it stays an ICU tool rather than a bedside screen (see qSOFA, below).
How SOFA defines sepsis under Sepsis-3
The 2016 Sepsis-3 consensus (Singer M et al., “The Third International Consensus Definitions for Sepsis and Septic Shock,” JAMA, 2016) redefined sepsis as “life-threatening organ dysfunction caused by a dysregulated host response to infection” — replacing the earlier SIRS-based definition (two or more of fever/tachycardia/tachypnea/abnormal white count), which the task force found too sensitive and non-specific to reliably identify patients at meaningfully elevated risk. Operationally, organ dysfunction is defined as an acute increase in total SOFA score of 2 points or more that is a consequence of the infection. Baseline SOFA is assumed to be zero unless a patient is known to have pre-existing organ dysfunction. In general hospital populations with suspected infection, a SOFA score of 2 or higher is associated with an in-hospital mortality risk of roughly 10% — the empirical basis the task force used to set that threshold.
Septic shock is a subset of sepsis defined by circulatory and cellular/metabolic abnormalities severe enough to substantially raise mortality risk. Clinically, Sepsis-3 operationalizes it as sepsis plus a persistent requirement for vasopressors to maintain mean arterial pressure ≥65 mmHg and a serum lactate >2 mmol/L despite adequate fluid resuscitation — a combination associated with hospital mortality exceeding 40% in the consensus dataset.
What qSOFA is, and why it’s a different tool
Quick SOFA (qSOFA) is a three-criterion bedside screen, not an abbreviated version of the SOFA score and not a diagnostic tool in its own right. It was introduced alongside Sepsis-3 specifically for settings where the labs full SOFA needs — blood gas, bilirubin, coagulation — aren’t routinely or immediately available: the emergency department, general wards, and pre-hospital care. The three criteria are:
- Respiratory rate ≥22 breaths/min
- Altered mentation (any acute change in mental status)
- Systolic blood pressure ≤100 mmHg
A patient meeting two or more of the three criteria is flagged as being at higher risk of a poor outcome from infection and warrants prompt further assessment — escalation of monitoring, lab work, and consideration of full SOFA scoring or ICU-level care — not an automatic sepsis diagnosis. This distinction matters in practice: qSOFA is a prompt to look closer, and the formal Sepsis-3 diagnosis of sepsis still runs through the SOFA-based organ-dysfunction threshold above, not through qSOFA alone.
qSOFA’s validation history is also more contested than SOFA’s. Subsequent studies after the original 2016 derivation found qSOFA is generally more specific but less sensitive than SIRS criteria for identifying patients who go on to have poor sepsis outcomes, particularly early in presentation — a real trade-off, not a settled improvement in every dimension. That finding is a major reason professional sepsis guidance (including the Surviving Sepsis Campaign) has cautioned against using qSOFA alone as a stand-alone sepsis screening tool, rather than as one input alongside clinical judgment and, where available, other early-warning scores.
SOFA vs. qSOFA at a glance
| SOFA | qSOFA | |
|---|---|---|
| Purpose | Quantify and track organ dysfunction; the diagnostic threshold for sepsis under Sepsis-3 | Rapid bedside risk flag prompting further assessment |
| Setting | ICU / anywhere labs are routinely drawn | ED, general wards, pre-hospital — no labs required |
| Inputs | 6 organ systems: respiratory, coagulation, hepatic, cardiovascular, CNS, renal | 3 criteria: respiratory rate, mentation, systolic BP |
| Sepsis relevance | Δ≥2 points = organ dysfunction = sepsis, per Sepsis-3 | ≥2 of 3 positive = escalate; not itself diagnostic |
Why the SOFA/qSOFA distinction matters beyond the bedside
For hospitals running sepsis-related quality programs and for teams pulling SOFA or qSOFA values into multi-site outcomes research, the screening-tool-vs-diagnostic-threshold distinction above isn’t academic. CMS’s SEP-1 severe sepsis and septic shock bundle measure is built around the Sepsis-3 clinical definitions and their specific timing and documentation rules — see our SEP-1 bundle measure guide for how those definitions translate into chart-abstraction criteria. And because SOFA components (creatinine, platelets, bilirubin, GCS, vasopressor dose, PaO₂/FiO₂) are often pulled from the EHR into research registries and risk-adjustment models rather than calculated fresh at each timepoint, inconsistent operational definitions of “baseline,” measurement timing, or how missing values are handled across sites can quietly distort a multi-site cohort’s apparent severity mix before any clinical difference is even in play — the same data-provenance discipline that matters for any structured research variable. Bedside deterioration-screening tools with a related but distinct design purpose are covered in our Early Warning Score implementation guide, and the broader family of risk-adjustment methods these scores feed into is covered in Observed-to-Expected (O/E) Ratio and Risk Adjustment and AHRQ Patient Safety Indicators Explained.
Frequently asked questions
What does a SOFA score of 2 or more mean?
An acute increase of 2 or more points in total SOFA score, in a patient with a suspected or confirmed infection, meets the Sepsis-3 operational definition of organ dysfunction — and therefore of sepsis. It is associated with roughly a 10% in-hospital mortality risk in general hospital populations with suspected infection, though absolute risk varies by clinical context.
Is qSOFA the same as SIRS?
No. SIRS (systemic inflammatory response syndrome) criteria — abnormal temperature, heart rate, respiratory rate, and white blood cell count — were the basis of the pre-2016 sepsis definition and are more sensitive but less specific than qSOFA. Sepsis-3 moved away from SIRS as the sepsis-defining criterion specifically because it flagged too many patients without meaningfully elevated risk; qSOFA is a different, narrower three-criterion screen introduced alongside that change, not a renamed version of SIRS.
Can qSOFA diagnose sepsis by itself?
No. A qSOFA score of 2 or higher identifies patients at higher risk of a poor outcome from infection and should prompt further evaluation, but the Sepsis-3 diagnostic threshold for sepsis runs through the full SOFA-based organ-dysfunction criterion, not qSOFA alone.
How is septic shock different from sepsis?
Septic shock is sepsis plus a persistent vasopressor requirement to maintain MAP ≥65 mmHg and a serum lactate above 2 mmol/L despite adequate fluid resuscitation — a combination associated with substantially higher mortality than sepsis without those circulatory and metabolic abnormalities.
Why does SOFA need labs that qSOFA doesn’t?
SOFA’s six organ-system scores depend on arterial blood gas, coagulation, liver, and renal chemistry values that are drawn routinely in ICU care but not necessarily immediately available in an ED or general-ward setting. qSOFA was deliberately built from three variables — respiratory rate, mental status, systolic blood pressure — that any clinician can assess at the bedside with no lab turnaround time.
