Identifying Sepsis and Infections in the Intensive Care Unit
Lengquist, Maria LU
(2026)
In Lund University, Faculty of Medicine Doctoral Dissertation Series
- Abstract
- Infections are a common reason for hospitalization, and when an infection is accompanied by organ failure, the patient is considered to have sepsis. The most severely ill sepsis patients are treated in the Intensive Care Unit (ICU). Identifying sepsis at ICU admission is, however, challenging, since most ICU patients present with organ failure and there is no gold standard for infection diagnosis. The aim of this thesis was to investigate different methods of identifying sepsis at ICU admission and infections in ICU patients.
Papers I–III were retrospective observational studies based on different subsets of the Swecrit cohort, an ICU population linked to the Swecrit biobank. Admission blood samples were collected to Swecrit from... (More) - Infections are a common reason for hospitalization, and when an infection is accompanied by organ failure, the patient is considered to have sepsis. The most severely ill sepsis patients are treated in the Intensive Care Unit (ICU). Identifying sepsis at ICU admission is, however, challenging, since most ICU patients present with organ failure and there is no gold standard for infection diagnosis. The aim of this thesis was to investigate different methods of identifying sepsis at ICU admission and infections in ICU patients.
Papers I–III were retrospective observational studies based on different subsets of the Swecrit cohort, an ICU population linked to the Swecrit biobank. Admission blood samples were collected to Swecrit from ICU patients between 2015 and 2018 in four ICUs in Sk ̊ane (Lund, Malm ̈o, Helsingborg, and Kristianstad). Clinical data were obtained from registries and medical records.
In Paper I, only 31% of patients who fulfilled sepsis-3 clinical criteria received an ICU main diagnosis of sepsis. In Paper II, among patients who fulfilled sepsis-3 clinical criteria, 25% were identified as sepsis mimics, as they did not meet more detailed infection criteria. In Paper III, we investigated calprotectin as a potential sepsis biomarker but found that its accuracy was lower (AUC 0.61) than that of the established biomarker C-reactive protein (CRP) (AUC 0.72, p<0.001). Paper IV is a research protocol for a planned study investigating if criteria for Ventilator Associated Pneumonia can be simplified for surveillance purposes.
We conclude that commonly used methods of identifying sepsis in ICU patients have impor- tant limitations, as they risk both under- and overestimating the frequency of sepsis at ICU admission. (Less)
Please use this url to cite or link to this publication:
https://lup.lub.lu.se/record/08561b61-9546-4716-9293-92d22cd2c0b5
- author
- Lengquist, Maria
LU
- supervisor
-
- Attila Frigyesi LU
- Lisa Mellhammar LU
- Hans Friberg LU
- opponent
-
- associate professor Hästbacka, Johanna, Tampere University, Finland
- organization
- publishing date
- 2026
- type
- Thesis
- publication status
- published
- subject
- keywords
- sepsis, critical care, infections, biomarkers, c-reactive protein, leukocytes, Shock, Septic/complications, Hospital-acquired bloodstream infection, calgranulin
- in
- Lund University, Faculty of Medicine Doctoral Dissertation Series
- issue
- 2026:32
- pages
- 105 pages
- publisher
- Lund University, Faculty of Medicine
- defense location
- Belfragesalen, BMC D15, Klinikgatan 32 i Lund
- defense date
- 2026-03-13 12:30:00
- ISSN
- 1652-8220
- ISBN
- 978-91-8021-830-6
- language
- English
- LU publication?
- yes
- id
- 08561b61-9546-4716-9293-92d22cd2c0b5
- date added to LUP
- 2026-01-26 15:12:42
- date last changed
- 2026-02-03 11:11:40
@phdthesis{08561b61-9546-4716-9293-92d22cd2c0b5,
abstract = {{Infections are a common reason for hospitalization, and when an infection is accompanied by organ failure, the patient is considered to have sepsis. The most severely ill sepsis patients are treated in the Intensive Care Unit (ICU). Identifying sepsis at ICU admission is, however, challenging, since most ICU patients present with organ failure and there is no gold standard for infection diagnosis. The aim of this thesis was to investigate different methods of identifying sepsis at ICU admission and infections in ICU patients.<br/><br/>Papers I–III were retrospective observational studies based on different subsets of the Swecrit cohort, an ICU population linked to the Swecrit biobank. Admission blood samples were collected to Swecrit from ICU patients between 2015 and 2018 in four ICUs in Sk ̊ane (Lund, Malm ̈o, Helsingborg, and Kristianstad). Clinical data were obtained from registries and medical records.<br/><br/>In Paper I, only 31% of patients who fulfilled sepsis-3 clinical criteria received an ICU main diagnosis of sepsis. In Paper II, among patients who fulfilled sepsis-3 clinical criteria, 25% were identified as sepsis mimics, as they did not meet more detailed infection criteria. In Paper III, we investigated calprotectin as a potential sepsis biomarker but found that its accuracy was lower (AUC 0.61) than that of the established biomarker C-reactive protein (CRP) (AUC 0.72, p<0.001). Paper IV is a research protocol for a planned study investigating if criteria for Ventilator Associated Pneumonia can be simplified for surveillance purposes.<br/><br/>We conclude that commonly used methods of identifying sepsis in ICU patients have impor- tant limitations, as they risk both under- and overestimating the frequency of sepsis at ICU admission.}},
author = {{Lengquist, Maria}},
isbn = {{978-91-8021-830-6}},
issn = {{1652-8220}},
keywords = {{sepsis; critical care; infections; biomarkers; c-reactive protein; leukocytes; Shock, Septic/complications; Hospital-acquired bloodstream infection; calgranulin}},
language = {{eng}},
number = {{2026:32}},
publisher = {{Lund University, Faculty of Medicine}},
school = {{Lund University}},
series = {{Lund University, Faculty of Medicine Doctoral Dissertation Series}},
title = {{Identifying Sepsis and Infections in the Intensive Care Unit}},
url = {{https://lup.lub.lu.se/search/files/240590125/Maria_Lengquist_-_WEBB.pdf}},
year = {{2026}},
}