qSOFA score: the three criteria and how they add up

The qSOFA (quick Sequential Organ Failure Assessment) score adds one point for each of three findings: a respiratory rate of 22 breaths per minute or more, altered mentation, and a systolic blood pressure of 100 mm Hg or less. The total runs from 0 to 3. A respiratory rate of 24, a systolic pressure of 95 and normal mentation give a qSOFA score of 2.

Not a medical device. Not a diagnosis or dosing recommendation.

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What is the qSOFA score?

qSOFA was introduced by Christopher W. Seymour and colleagues in a 2016 JAMA paper written for the Third International Consensus Definitions for Sepsis and Septic Shock (Sepsis-3). It's also called quick SOFA, Sepsis-3 qSOFA or Seymour qSOFA.

The 2016 abstract describes it as "a new model derived using multivariable logistic regression in a split sample, the quick Sequential [Sepsis-related] Organ Failure Assessment (qSOFA) score (range, 0-3 points, with 1 point each for systolic hypotension [≤100 mm Hg], tachypnea [≥22/min], or altered mentation)."

This page explains the criteria and how the total is built. It doesn't give a cutoff for interpreting the total, and a qSOFA score doesn't establish sepsis.

The qSOFA formula

qSOFA = (respiratory_rate >= 22 ? 1 : 0)
      + (altered_mentation ? 1 : 0)
      + (systolic_mm_hg <= 100 ? 1 : 0)

Exact expression the calculator uses:

qSOFA = respiratory_rate_ge_22 + altered_mentation + systolic_mm_hg_le_100; each 1 if present; max 3

Maximum score: 3.

The three criteria

Criterion	Input	Scores 1 point when	Example that scores 0
Fast breathing (tachypnea)	`respiratory_rate`, breaths/min (4–80)	22 or more	21
Altered mentation	`altered_mentation`, true or false	true	false
Low systolic blood pressure	`systolic_mm_hg`, mm Hg (50–250)	100 or less	101

How to calculate qSOFA

Respiratory rate. Count breaths per minute. 22 or more scores 1; 21 or fewer scores 0.
Mentation. If mentation is altered, score 1. Magent's record notes that Seymour 2016 defined this as a Glasgow Coma Scale score below 15, but the calculator doesn't compute GCS; the caller answers true or false.
Systolic blood pressure. 100 mm Hg or less scores 1; 101 or more scores 0.
Add the three. The total is 0, 1, 2 or 3.

Notice the direction of each comparison. Respiratory rate scores at 22 and above. Systolic pressure scores at 100 and below. Both edge values (22 and 100) count.

What the calculator returns

Magent's calculator returns the total score and the maximum of 3. It doesn't return a label or band for the total.

Worked examples

Examples 1–6 use Magent's own expected values for the calculator. Example 7 is worked from the formula.

Example 1: no criteria

Respiratory rate 16: under 22 → 0.
Mentation not altered → 0.
Systolic 120: over 100 → 0.
qSOFA = 0 (of 3).

Example 2: respiratory rate exactly 22

Respiratory rate 22 → 1.
Mentation not altered → 0; systolic 120 → 0.
qSOFA = 1.

Example 3: respiratory rate 21

Respiratory rate 21: under 22 → 0.
qSOFA = 0.

Example 4: systolic exactly 100

Respiratory rate 16 → 0; mentation not altered → 0.
Systolic 100 → 1.
qSOFA = 1.

Example 5: systolic 101

Systolic 101: over 100 → 0.
qSOFA = 0.

Example 6: all three

Respiratory rate 22 → 1.
Mentation altered → 1.
Systolic 100 → 1.
qSOFA = 3 (the maximum).

Example 7: two of three

Respiratory rate 24 → 1.
Mentation not altered → 0.
Systolic 95 → 1.
qSOFA = 2.

qSOFA reference table

Each row is one of Magent's expected values for the calculator.

Respiratory rate	Altered mentation	Systolic (mm Hg)	qSOFA
16	No	120	0
22	No	120	1
21	No	120	0
16	Yes	120	1
16	No	100	1
16	No	101	0
22	Yes	100	3

History of qSOFA

The score comes from Christopher W. Seymour, Vincent X. Liu, Theodore J. Iwashyna and colleagues, Assessment of Clinical Criteria for Sepsis: For the Third International Consensus Definitions for Sepsis and Septic Shock (Sepsis-3), JAMA, 2016 (volume 315, issue 8, pages 762–774).

The abstract notes that the Sepsis-3 task force "defined sepsis as 'life-threatening organ dysfunction due to a dysregulated host response to infection.'" The study set out "To evaluate the validity of clinical criteria to identify patients with suspected infection who are at risk of sepsis."

It drew on "1.3 million electronic health record encounters from January 1, 2010, to December 31, 2012, at 12 hospitals in southwestern Pennsylvania," with confirmatory analyses in "4 data sets of 706,399 out-of-hospital and hospital encounters at 165 US and non-US hospitals." The paper compared qSOFA with the SOFA score, the SIRS criteria and the Logistic Organ Dysfunction System (LODS) score.

When it's used

In the 2016 study, qSOFA was assessed in patients with suspected infection, alongside SOFA, SIRS and LODS.

Where it's used

The study's data came from hospitals in southwestern Pennsylvania, with confirmatory data sets from out-of-hospital and hospital encounters at 165 US and non-US hospitals.

Who uses it

The paper was written for the Sepsis-3 consensus task force.

Limits of the calculation

It adds three criteria. It doesn't assess infection and doesn't establish sepsis.
Altered mentation is the caller's call. The calculator doesn't compute a Glasgow Coma Scale score.
It's qSOFA. It isn't the full SOFA score, which uses lab values and organ support across six systems.
It returns the total alone. This page doesn't give a cutoff for interpreting it.

Clinical decisions belong to a qualified clinician who knows the patient.

How it differs from related calculators

SOFA is the full Sequential Organ Failure Assessment. Magent's record describes it as using PaO2/FiO2, platelets, bilirubin, mean arterial pressure and vasopressors, Glasgow Coma Scale, and creatinine or urine output.
SIRS criteria count four findings: temperature, heart rate, respiratory rate or PaCO2, and white cell count. The respiratory-rate criterion there is different from qSOFA's.

Glossary

Tachypnea: breathing faster than usual.
Mentation: mental state; altered mentation means confusion or reduced responsiveness.
Systolic blood pressure: the top number in a blood pressure reading.
SOFA: Sequential (Sepsis-related) Organ Failure Assessment.
Sepsis-3: the 2016 Third International Consensus Definitions for Sepsis and Septic Shock.

Common mistakes

Missing the edge values. A respiratory rate of exactly 22 and a systolic of exactly 100 both score.
Flipping the blood pressure direction. Systolic scores when it's 100 or lower, not higher.
Confusing qSOFA with SOFA. qSOFA has three criteria and no labs; SOFA is a separate, larger score.
Mixing up the SIRS respiratory rate. SIRS uses its own respiratory-rate criterion, not 22.

Source

Seymour CW, Liu VX, Iwashyna TJ, et al. Assessment of Clinical Criteria for Sepsis: For the Third International Consensus Definitions for Sepsis and Septic Shock (Sepsis-3). JAMA. 2016;315(8):762-774. DOI: 10.1001/jama.2016.0288

Frequently asked questions

How do you calculate a qSOFA score?

Add one point each for a respiratory rate of 22 or more, altered mentation, and a systolic blood pressure of 100 mm Hg or less. The total is 0 to 3.

What qSOFA score is positive?

This page doesn't give a cutoff. It shows how the total is built.

What are the three qSOFA criteria?

Respiratory rate 22 or more breaths per minute, altered mentation, and systolic blood pressure 100 mm Hg or less.

What does qSOFA stand for?

Quick Sequential (Sepsis-related) Organ Failure Assessment.

Is qSOFA the same as SOFA?

No. qSOFA uses three criteria with no labs. SOFA is the full organ-failure score.

Who created qSOFA?

Christopher Seymour and colleagues, in a 2016 JAMA paper for the Sepsis-3 consensus definitions.