Long-term outcomes of ICU-acquired infections with a focus on bloodstream infections: a single-center retrospective registry study.

Abstract

Objectives: Intensive care unit (ICU) patients have an increased risk of bacteremia. We aimed to investigate the 5-year outcome of ICU-acquired infections comparing them with ICU patients without new infections. Our second aim was to compare the outcome of Gram-positive, Gram-negative and fungal ICU-acquired bloodstream infections (BSIs).

Methods: This single-center retrospective registry study occurred in an academic teaching hospital during 2000-2017 in a mixed adult ICU consisting of patients who stayed longer than 48 h in the ICU. Data was retrieved from the ICU and hospital electronic data management systems. Three groups were included: no infection and no new antimicrobial treatment, a new ICU-acquired infection with negative blood cultures (BCs), and a new ICU-acquired BSI. A multivariable-adjusted Cox proportional hazards model was used to determine the impact of ICU-acquired infection on 5-year mortality.

Results: 1857 had no infection and 768 developed an ICU-acquired infection with positive BCs in 195 cases (25.4%). The adjusted HR was 2.03 (95% CI from 1.76-2.35, p < 0.001) for the impact of ICU-acquired infection on 5-year mortality. The highest median sequential organ failure assessment (SOFA) was 7.0 (5.0-8.0) for the no-infection group, 9.0 (7.0-10.0) for the BC-negative ICU-acquired infection group, and 12.0 (9.0-15.0) for the ICU-acquired BSI patients (p < 0.001). The crude 30-day mortalities in the no-infection, the BC-negative, and the BSI groups were 98 (5.5%), 58 (10.1%), and 51 (26.0%), respectively (p < 0.001). The highest median SOFA for Gram-positive BSIs was 11.0 (8.0-13.0), for Gram-negative BSIs 13.0 (11.0-16.0), and for fungal BSIs 12.5 (10.0-16.0) (p = 0.01). The need for RRT was 23.2% (19) in Gram-positive, 29.8% (14) in Gram-negative, and 48.1% (25) in fungal BSIs (p = 0.01). The crude ICU-mortalities were 12.2% (10) in Gram-positive BSIs, 31.9% (15) in Gram-negative BSIs, and 11.5% (6) in fungal BSIs (p = 0.008). Patients with fungal BSI had the worst 5-year outcome, whereas the long-term outcome did not differ between Gram-positive and Gram-negative BSIs.

Conclusions: Patients with ICU-acquired infections had three times higher 5-year mortality than non-infected ICU patients. ICU-acquired Gram-negative BSIs had the highest ICU mortality, whereas the long-term outcome did not differ between Gram-negative and Gram-positive ICU-acquired BSIs. Fungal BSI showed the worst long-term outcome.