Impact of bloodstream infections on ICU mortality

Introduction

Previous studies have investigated the impact of different types of bloodstream infection (BSI) (primary, secondary, catheter-related) on the outcome of critically ill patients, including only the first BSI episode in the analysis [1–3]. Our study aimed at evaluating the impact of different BSI types on ICU mortality including the total number of each type of BSI in the analysis.

Methods

All patients admitted in the ICU during a 46-month period were prospectively followed. Data recorded included: demographics, medical history, admission category (medical, elective surgical, emergency surgical, trauma), APACHE II score at admission to the ICU, BSI episodes, isolated pathogens, continuous renal replacement therapy (CRRT) implementation, blood product transfusions, ICU length of stay (LOS) and ICU outcome. BSIs were defined as primary (PBSI), secondary, catheter-related or mixed based on standard criteria. Data were analyzed with logistic regression, and the statistical significance level set at P < 0.05.

Results

Four hundred and twenty-six consecutive patients (295 males, 131 females) were included in the analysis. Age (mean ± SD) was 52.5 ± 19.4 years, APACHE II score at admission to the ICU 18.3 ± 6.6. The BSI incidence density was 26.3 episodes per 1,000 patient-days. ICU LOS was 21.6 ± 20.6 days. ICU mortality rate was 17.8% (95% CI = 14.3 to 21.6). In univariable analysis, the APACHE II score, age, admission category, CRRT implementation, PBSI episodes, and packed red blood cell (pRBC) units transfused during the ICU LOS were significantly associated with ICU mortality. In multivariable analysis, age (OR = 1.2, P = 0.003), APACHE II score (OR = 1.1, P < 0.001), infection at admission (OR = 2.9, P = 0.007), CRRT implementation (OR = 9.3, P < 0.001), PBSI episodes (OR per episode = 2.7, P = 0.002) and pRBC transfusions (OR = 1.1, P = 0.003) were independently associated with ICU mortality. None of the other BSI types showed association with ICU mortality.

Conclusion

In our patient sample, PBSI episodes during the ICU LOS were independently associated with ICU mortality, each PBSI episode conferring a 2.7-fold probability of ICU death after adjustment for potential confounders. The other BSI types (secondary, catheter-related) showed no association with ICU mortality.