staging and severity
Definitions, staging
and severity in sepsis
How the definition of sepsis has evolved over the past two decades,
identifying patients at greater risk of poor outcomes from sepsis,
and defining sepsis in paediatric and low-income countries is discussed
Madeline Coxwell
Matthewman
MBBS BSc PGCME
Mervyn Singer
MB BS MD FRCP(Lon)
FRCP(Edin) FFICM
University College
London Hospital,
London, UK
With an estimated 31 million annual cases of
sepsis globally, 1 the World Health Organization
has identified sepsis as a global health priority. 2
In 2016, the Society of Critical Care Medicine
and the European Society of Intensive Care
Medicine announced a marked change in the
definition of sepsis. Moving away from a focus
on inflammation, sepsis is now defined as
“life-threatening organ dysfunction caused by
a dysregulated host response to infection”. 3
Defining sepsis
The initial consensus definition of sepsis (Sepsis-1)
created in 1991 4 and revised in 2001 5 (Sepsis-2),
focussed on the then-prevailing view that sepsis
was caused by an excessive inflammatory
response by the host to infection. Sepsis was
diagnosed if a patient had two or more of the
systemic inflammatory response syndrome (SIRS)
criteria and suspected or confirmed infection.
The SIRS criteria comprise abnormalities in three
clinical variables (heart rate, temperature,
respiratory rate) and one laboratory value (white
cell count). SIRS criteria are not specific to sepsis
4
HHE 2018 | hospitalhealthcare.com
and can be fulfilled by a wide range of other
conditions, including heart failure, endocrine
disorders, trauma and surgery. A prospective
study of 3147 patients in 198 intensive care units
found 93% of patients fulfilled two or more SIRS
criteria during their stay. 6 SIRS criteria are neither
highly sensitive; in a study of 109,663 patients in
172 Australian and New Zealand intensive care
units, 12.1% of patients admitted with infection-
related organ failure did not qualify as being
septic using SIRS criteria. 7
The inadequate specificity and sensitivity
of SIRS and the growing evidence that sepsis is
far more than excess inflammation, led to the
creation of the Sepsis-3 Task Force in 2014.
Composed of 19 expert sepsis clinicians and
researchers, the Sepsis-3 Task Force markedly
changed the definition of sepsis, eliminating
the term severe sepsis and the SIRS criteria,
and providing precise clinical criteria to
characterise the condition. The new definition
highlights the three important elements of
sepsis; the infection, the host response and
organ dysfunction.