Predictors of mortality among adult, old and the oldest old patients with bloodstream infections: An age comparison

Background: Bloodstream infections (BSIs) are a major cause of mortality in elderly. Objective of the study is to identify factors predictive of mortality in old and oldest old patients. Methods: This is a single centre retrospective observational study, including all patients admitted to Fondazione Policlinico A. Gemelli university hospital and diagnosed with BSI. Patients were stratified into three groups according to age: adult (A), younger than 65; old (O), aged between 65 and 80; oldest old (OO), older than 80. Primary outcome was 30-day in-hospital mortality. Secondary outcomes were duration of antimicrobial therapy (DOT) and length of hospital stay (LOS). Results: Of the 1034 patients included in the study, 346 were in group A, 447 in group O and 241 in group OO. The rate of 30-day mortality raised from 6.9% (24/346) in group A to 10.8% (84/447) in group O and 33.2% (80/241) in group OO (p<0.01), while DOT and LOS significantly decreased moving from adults to oldest old (p<0.01). Methicillin-resistant Staphylococcus aureus (MRSA) and Enterococcus spp were both independently correlated to an increased 30-day mortality risk selectively in patients older than 80 (MRSA: HR 2.37, p=0.03; Enterococcus spp: HR 2.44, p=0.01). Conclusions: BSIs have a high impact on survival in old and oldest old patients. BSIs by gram-positive pathogens, in particular MRSA and Enterococcus spp, should be a wake-up call for physicians, who should focus efforts on adequate and prompt antibiotic and support treatment.

Automated summary

This study identified that mortality rates were higher in old and oldest old patients, with those over 80 having a higher risk of death when infected with MRSA or Enterococcus spp. Duration of antimicrobial therapy and length of hospital stay decreased significantly with advancing age.