All-cause and infection-attributable mortality amongst adults with bloodstream infection – a population-based study

Background

Bloodstream infections (BSI) are common, life threatening infections. However, it remains unclear whether deaths following BSI are primarily due to uncontrolled infection or underlying comorbidities. We aimed to determine the overall mortality, infection-attributable mortality, and causes of death for four leading bloodstream infection (BSI) pathogens.

Methods

This retrospective cohort study was conducted within the Secure Anonymised Information Linkage (SAIL) Databank, containing anonymised population-scale electronic health record data for Wales, UK. We included adults with Escherichia coli, Klebsiella sp, Pseudomonas aeruginosa and Staphylococcus aureus BSI between 2010-2022 using linked data from Public Health Wales and the Office for National Statistics. 30-day all-cause and sepsis-specific mortality, as a proxy for infection-attributable mortality, were compared using Cox proportional hazards and competing risk regression respectively.

Results

We identified 35,691 adults with BSI (59.6% E. coli). Adjusted analyses revealed that all organisms had a higher 30-day mortality vs. E. coli with Pseudomonas aeruginosa the highest (HR: 1.96 [1.76-2.17], p < 0.001).

Cancer was the leading cause of death following BSI for all organisms, particularly deaths occurring between 30-90 days (35.9%). 25.5% of deaths within 30 days involved sepsis. MRSA was associated with the highest sepsis mortality vs. E. coli (HR: 2.56 [2.10-3.12], p < 0.001). Peak CRP was positively associated with increased sepsis mortality (p < 0.001).

Conclusions

This population-level study challenges the assumption that most deaths following BSI are directly attributable to uncontrolled infection, particularly sub-acutely more than 30 days from BSI. Our findings underscore the need for re-evaluating clinical trial design and developing better preventative strategies for BSI.