The epidemiology of sepsis in Scottish intensive care units

Introduction

Recent developments [1] have increased the requirement for good clinical data on the aetiology, incidence and outcome from sepsis in the intensive care unit (ICU). Assessment of sepsis in the Scottish ICU database has previously been limited. Our aim was to conduct a prospective audit of sepsis, severe sepsis and septic shock following ICU admission in Scotland using predetermined sepsis criteria.

Methods

Between January 2002 and 31 May 2002, 25 of the 26 adult, general ICUs in Scotland participated in a prospective audit of sepsis. Daily data were recorded on Ward Watcher software (Critical Care Audit Ltd) enabling identification of the first episode of sepsis: fulfilment of the systemic inflammatory response syndrome (SIRS) [2] criteria in response to infection. First 24-hour APACHE II scores are generated routinely in Scottish ICUs; however, source and type of infection and a sepsis-related organ failure assessment (SOFA) [3] were also mandatory in patients identified as septic.

Results

In this 5 month study, 46% (n = 1618) of ICU admissions developed sepsis, equating to 0.77 cases per 1000 population, per annum, in Scotland. Sepsis was present at, or shortly after, admission (median of 1 day). ICU length of stay (LOS) was double that of the Scottish ICU population (mean = 9.02 days, median = 5.1 days). Of all admissions, 38% (n = 1341) had severe sepsis or septic shock. Two-thirds of this group had more than one organ failure, of which 290 also had an APACHE II score of 25 or more. Both mortality and APACHE score rose with the number of organs failing. In those with severe sepsis or septic shock, the major source of sepsis (bronchopulmonary = 56.5%) and the ICU mortality (33%) were similar to those of the placebo group in the PROWESS study [1]. The septic shock group had a significantly higher ICU mortality than those with severe sepsis (61.5% vs 31.8%, P < 0.0001). Mean SOFA (10.9 vs 5.1, P < 0.0001) and APACHE II scores (24.1 vs 20, P < 0.0001) were also significantly higher in this group.

Conclusion

Almost one-half of the admissions to Scottish ICUs have sepsis, which presents on or shortly after admission. Mortality increases with APACHE score and the number of organs failing. Septic shock appears to be significantly associated with poor outcome.