Dr. Tang Miu Yee Michele, Department of Intensive Care, Princess Margaret Hospital, Supervisor: Dr. Tong Chak Kwan
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Objectives
The purpose of this study is to assess the mortality of patients with community-onset bloodstream infection in the intensive care unit (ICU) of Princess Margaret Hospital (PMH), and to identify prognostic indicators of mortality in this population.
Methods
Medical records of patients with community-onset bloodstream infection admitted to ICU of Princess Margaret Hospital during the period between January 2005 and December 2009 were reviewed retrospectively. Baseline demographic and clinical data on admission to ICU were collected. Clinical outcomes of ICU and hospital mortality were recorded. Univariate and multivariate analyses were used to identify the prognostic indicators of mortality and Kaplan Meier method was performed for survival analysis.
Results
Of 3518 admissions during the study period, 178 patients having community-onset BSI were identified. ICU mortality and hospital mortality were 38.8% and 42.1% respectively. They were further classified into community-acquired and healthcare-associated bloodstream infection. There were 121 patients having community-acquired bloodstream infection. The ICU mortality was 39.7%. Their mean APACHE II in non-survivors was significantly higher than those in survivors (35.4±10.1 versus 20.9±7.9; p<0.001) and likewise the median SOFA score (14 [12,16] versus 8 [5,11]; p<0.001). Multivariate analysis found that white cell count <4,000/μL (OR 14.326); platelet count ≤91,000/μL (OR 3.475); mechanical ventilation (OR 9.756); antibiotic discordance (OR 15.248) were associated with increased mortality. Fifty seven patients were identified as having healthcare-associated bloodstream infection. The ICU mortality in this group of patient was 36.8%. APACHE II score (34.9±9.0 versus 26.3±8.3) and SOFA score (13.3±3.6 versus 10.2±3.2) were significantly higher in non-survivors than in survivors. In addition, mechanical ventilation was another risk factor associated with higher mortality identified in univariate analysis (p<0.005).
Conclusion
Community-acquired bloodstream infection with ICU admission carried a high risk of mortality. Low white cell count (<4000/μL), low platelet count (≤91,000/μL), mechanical ventilation and antibiotic discordance were independent predictors of mortality. Every effort should target at coverage of possible causative organisms and this relies on a continuous update and evaluation of local epidemiological pattern. Healthcare-associated bloodstream infection accounted for a significant proportion (32%) of community-onset bloodstream infection admitted to ICU. With the trend of shifting modern medical care from hospital to community, we will expect dramatic changes in characteristics of infections that were previously classified as community-acquired and further studies are needed to identify the importance of healthcare-associated infection in ICU patients.