Sepsis and Deterioration Screening Scores
Published October 11, 2026 · Last updated October 11, 2026
How qSOFA, SOFA, SIRS criteria, NEWS2, and the shock index fit into detecting sepsis and clinical deterioration — including the shift in sepsis definitions from SIRS to the Sepsis-3 qSOFA/SOFA framework.
Sepsis screening and the detection of clinical deterioration work at different altitudes. Some tools are quick bedside filters for suspected infection, others quantify organ dysfunction in the critically ill, and others score deranged physiology to trigger a response. Confusing one for another is a frequent source of misuse.
This guide explains what each of the five screening and severity calculators measures and the setting each was designed for.
The sepsis definition shift: from SIRS to qSOFA
The SIRS criteria (four physiologic criteria — temperature, heart rate, respiratory rate, and leukocyte count) defined sepsis from the early 1990s consensus. The Third International Consensus Definitions (Sepsis-3) moved away from SIRS, defining sepsis as organ dysfunction caused by infection and complementing the SOFA score with the quick qSOFA tool.
The SIRS criteria calculator remains in the library because SIRS-based criteria are still embedded in many protocols and older documentation, but it is important to know that the current consensus framework is the Sepsis-3 one.
qSOFA: a bedside trigger in suspected infection
The qSOFA score uses altered mentation, tachypnea, and hypotension to identify adults outside the intensive care unit with a suspected infection who are at higher risk of sepsis-related organ dysfunction and death. It is a screening and escalation prompt rather than a diagnostic definition — a quick way to raise the index of suspicion and escalate care.
SOFA: quantifying organ dysfunction
The SOFA score quantifies organ dysfunction across six organ systems and is used in critically ill patients; under Sepsis-3, sepsis is operationally identified by an acute change in the baseline SOFA score of 2 points or more in the setting of infection. Because it requires laboratory and physiologic inputs, it belongs in the ICU or comparable settings rather than at the first bedside glance.
NEWS2: detecting deterioration on the ward
The National Early Warning Score 2 (NEWS2) standardizes the assessment of acute-illness severity in adult inpatients by scoring routine bedside observations and linking score bands to mandated clinical response levels. It is a general deterioration tool, not a sepsis tool specifically, and it is the established framework in the NHS for triggering escalation of care.
The shock index as a hemodynamic adjunct
The shock index relates heart rate to systolic blood pressure. An inappropriately high heart rate relative to the blood pressure flags impaired hemodynamic status, and a calculated index can work as a quick adjunct to the scoring tools above, particularly in detecting early critical illness. It is not itself a sepsis screen.
Match the tool to the setting
In the emergency department or on the ward with suspected infection, qSOFA is the Sepsis-3 bedside filter; in the ICU, SOFA quantifies organ dysfunction; on the general ward, NEWS2 scores deterioration across all causes; the shock index gives a continuous hemodynamic signal; and SIRS persists in legacy protocols. Choosing among them is fundamentally a question of setting and question.
Calculators in this guide
Related guides
References
- Seymour CW, et al. Assessment of Clinical Criteria for Sepsis. JAMA 2016;315(8):762-774.
- Singer M, et al. The Third International Consensus Definitions for Sepsis and Septic Shock (Sepsis-3). JAMA. 2016;315(8):801-810.
- Vincent JL, et al. The SOFA (Sepsis-related Organ Failure Assessment) score to describe organ dysfunction/failure. Intensive Care Med. 1996;22(7):707-710.
- Bone RC, et al. Definitions for sepsis and organ failure and guidelines for the use of innovative therapies in sepsis. Chest. 1992;101(6):1644-1655.
- Royal College of Physicians. National Early Warning Score (NEWS) 2: Standardising the assessment of acute-illness severity in the NHS. RCP, 2017.
- Rady MY, et al. A comparison of the shock index and conventional vital signs to identify acute, critical illness in the emergency department. Ann Emerg Med. 1994;24(4):685-690.