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.