Mortality of Sepsis in Swedish Intensive Care Units 2008-2016
Conditions: Sepsis
Sponsor: Uppsala University

Study protocol synopsis and statistical plan for “Mortality of Sepsis in Swedish Intensive 
Care Units 2008 – 2016” 
Study protocol: 20th March 2018 
Principal Investigator: Miklós Lipcsey, MD, PhD 
Investigators: Gunnar Strandberg, PhD, Sten Walther, PhD, Christina Agvald-Öhman, PhD. 
Background 
Accurate data on mortality in sepsis are important for several reasons, including allocation of 
resources, benchmarking, evaluation of interventions and for research purposes. Recent studies have 
indicated that the mortality of sepsis has decreased in the 21th century, although this view is not 
undisputed. Moreover, data on outcome beyond hospital discharge is limited. However, if mortality 
figures have improved, the cause of this is not entirely clear [1-3]. Preliminary data from Swedish 
intensive care units indicate that the mortality in sepsis may be relatively stable over the last decade 
in this setting. Therefore, we aim to study sepsis mortality from 2008 – 2016 in register data from 
Swedish intensive care units, and contrast this with mortality in other ICU patients. The specific 
research question is whether mortality has changed during this period. Primary outcomes are 
mortality at 30, 90 and 365 days after ICU admission. Secondary outcomes are hospital mortality and 
ICU and hospital length of stay.   
Methods 
Data are recovered from the Swedish Intensive Care Registry (SIR), a centrally administered 
nationwide collaboration where all general of intensive care units (ICU) in Sweden are members. We 
will include all adult (≥18 years) patients admitted to a general ICU between 1st of January 2008 and 
18th of October 2016 (thoracic, neurosurgical, pediatric and burns ICUs are excluded). The cohort is 
divided in septic and non-septic patients. The former are identified by any of the International 
Classification of Diseases (ICD)-10 diagnoses R65.1, R57.2 and A41.9, which are used in the register to 
classify severe sepsis and septic shock. Data from SIR are linked with data from the national inpatient 
register of the Swedish Board of Health and Welfare (Socialstyrelsen), to recover chronic comorbidity 
data.  
The septic and non-septic groups are characterized with regard to demographic factors; age, sex and 
type of treating hospital (regional, county, local), comorbidity; Charlson Comorbidity Index (CCI) and 
selected key diagnoses; diabetes, chronic heart or lung disease and malignancy, level of acute illness 
severity; Simplified Acute Physiology (SAPS)3 score, and selected interventions; invasive ventilation 
and renal replacement therapy. Also, ICU and hospital length of stay are described. These factors are 
described with appropriate statistics, i.e. mean and standard deviation (SD) or median and 
interquartile range (IQR) for parametric and nonparametric variables, or as proportions, and the 
beginning and end of the period are compared with t-test, u-test or χ2-test, respectively.  
Proportional unadjusted mortality at hospital discharge, 30 days, 90 days and 365 days is also 
described in the whole population and in subgroups based on age, sex, type of treating hospital and 
severity of acute illness and chronic comorbidity.   
The primary outcome measures; mortality at 30, 90 and 365 days after ICU admission, are further 
studied with logistic regression, adjusting for acute illness severity, comorbidity and demographic 
factors. Admission year is included as a regressor to assess the effect of time.     
 

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Kaukonen KM, Bailey M, Suzuki S, Pilcher D, Bellomo R, (2014) Mortality related to severe 
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