Open Access Research article

A latent class approach for sepsis diagnosis supports use of procalcitonin in the emergency room for diagnosis of severe sepsis

Fabián A Jaimes167*, Gisela D De La Rosa2, Marta L Valencia1, Clara M Arango13, Carlos I Gomez3, Alex Garcia4, Sigifredo Ospina5, Susana C Osorno1 and Adriana I Henao1

Author Affiliations

1 Department of Internal Medicine, School of Medicine, Universidad de Antioquia, Medellín AA 1226, Colombia

2 Department of Critical Care, Hospital Pablo Tobón Uribe, Medellín, Colombia

3 Department of Internal Medicine, Hospital Pablo Tobón Uribe, Medellin, Colombia

4 Intensive Care Unit, Clínica Universitaria Bolivariana, Medellín, Colombia

5 Department of Epidemiology, Hospital Universitario San Vicente de Paul, Medellín, Colombia

6 Research Unit, Hospital Pablo Tobón Uribe, Medellín, Colombia

7 Grupo Académico de Epidemiología Clínica (GRAEPIC), Universidad de Antioquia, Medellín, Colombia

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BMC Anesthesiology 2013, 13:23  doi:10.1186/1471-2253-13-23

Published: 19 September 2013



Given the acknowledged problems in sepsis diagnosis, we use a novel way with the application of the latent class analysis (LCA) to determine the operative characteristics of C-reactive protein (CRP), D-dimer (DD) and Procalcitonin (PCT) as diagnostic tests for sepsis in patients admitted to hospital care with a presumptive infection.


Cross-sectional study to determine the diagnostic accuracy of three biological markers against the gold standard of clinical definition of sepsis provided by an expert committee, and also against the likelihood of sepsis according to LCA. Patients were recruited in the emergency room within 24 hours of hospitalization and were follow-up daily until discharge.


Among 765 patients, the expert committee classified 505 patients (66%) with sepsis, 112 (15%) with infection but without sepsis and 148 (19%) without infection. The best cut-offs points for CRP, DD, and PCT were 7.8 mg/dl, 1616 ng/ml and 0.3 ng/ml, respectively; but, neither sensitivity nor specificity reach 70% for any biomarker. The LCA analysis with the same three tests identified a “cluster” of 187 patients with several characteristics suggesting a more severe condition as well as better microbiological confirmation. Assuming this subset of patients as the new prevalence of sepsis, the ROC curve analysis identified new cut-off points for the tests and suggesting a better discriminatory ability for PCT with a value of 2 ng/ml.


Under a “classical” definition of sepsis three typical biomarkers (CRP, PCT and DD) are not capable enough to differentiate septic from non-septic patients in the ER. However, a higher level of PCT discriminates a selected group of patients with severe sepsis.

Sensitivity; Specificity; Sepsis; Latent class; C-reactive protein; Procalcitonin; D-dimer