There are multiple scoring systems and definitions for sepsis and sepsis with organ dysfunction. None is perfect and many seek to measure similar variables.

In February 2016, new definitions of sepsis and septic shock were published by the Third International Consensus group; the so-called ‘Sepsis-3’ definitions.[43] Sepsis was redefined by Sepsis-3 as “life-threatening organ dysfunction caused by a dysregulated host response to infection”.[43]

Organ dysfunction is defined as a change of 2 or more points in the Sequential (or Sepsis-related) Organ Failure Assessment (SOFA) score.[43]Sequential (or Sepsis-related) Organ Failure Assessment (SOFA) criteria[Figure caption and citation for the preceding image starts]: Sequential (or Sepsis-related) Organ Failure Assessment (SOFA) criteriaCreated by BMJ, adapted from Vincent JL, Moreno R, Takala J, et al. The SOFA (Sepsis-related Organ Failure Assessment) score to describe organ dysfunction/failure. On behalf of the Working Group on Sepsis-Related Problems of the European Society of Intensive Care Medicine. Intensive Care Med 1996;22:707-10. [Citation ends].

The shift away from the previous definitions (which described sepsis as a systemic inflammatory response syndrome [SIRS] arising due to a new infection) aimed to facilitate earlier diagnosis as well as greater consistency for research outcomes.[43] 

In the first international consensus definitions, which date from 1991, severe sepsis was defined as sepsis associated with organ dysfunction, hypoperfusion, or hypotension; septic shock was defined as sepsis with hypotension despite adequate fluid replacement.[3] However, the 2016 Third International Consensus Group (Sepsis-3) definitions state that the term 'severe sepsis' should be made redundant in light of the revisions to the definition of sepsis.[43]

Acute Physiology and Chronic Health Evaluation II score (APACHE II)[128]

The APACHE score is commonly used to establish illness severity in the intensive care unit (ICU) and predict the risk of death.[ APACHE II scoring system ] There is a high risk of death if the score is ≥25.

Other sepsis risk-scoring models

Several other models have been developed for use in the ICU, including APACHE III, the Simplified Acute Physiology Score, and Mortality Probability Model II.[129][130][131]

Patient group-specific scoring systems have also been developed. For example, the Predisposition Insult Response and Organ failure and Mortality in Emergency Department Sepsis scores have been developed to risk stratify patients with sepsis or septic shock who are admitted to the accident and emergency department;[132] the Sepsis in Obstetrics Score has been developed to risk stratify pregnant or postnatal women with sepsis.[73] These scoring systems can assist in the identification and management of sepsis in specific patient groups.[133]

There are numerous ongoing studies investigating techniques for 'staging' the severity of sepsis using a variety of blood-borne markers.[134][135] Although some techniques have shown initial promise, the evidence base remains weak, and they have an unclear role in future clinical practice.

Risk stratification

In any patient in whom sepsis is a possibility, use a systematic process to check vital observations and assess and record the risk of deterioration.[41][42][43] Remember that no risk stratification process is 100% sensitive or 100% specific; therefore, you must use your clinical judgement. 

Consult local guidelines for the recommended approach for assessing acute deterioration.

  1. In hospital: use the National Early Warning Score 2 (NEWS2) or an alternative early warning score.[41][42][44] NEWS2 is endorsed by NHS England for use in this setting.[41]

  2. In the community: use an early warning score such as NEWS2, which is recommended by NHS England[41] and the Royal College of General Practitioners in the UK,[50] or the UK National Institute for Health and Care Excellence high-risk criteria.[3]

    • None is validated in primary care.[50]

NEWS2 is the most widely used early warning score in the UK National Health Service and is endorsed by NHS England.[41] NHS England: Sepsis external link opens in a new window In a patient with a known or likely infection, a NEWS2 score of 5 or more is likely to indicate sepsis.[42]

See the Risk stratification subsection of Diagnosis recommendations for more information. 

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