Advanced Age is not a Risk Factor for Mortality in Patients with Bacteremia Caused by Extended-Spectrum β-Lactamase-Producing Organisms: a Multicenter Cohort Study.

A 5-year multicenter retrospective cohort study was conducted across six hospitals in Niigata, Japan. Patients (n = 179) with bacteremia due to extended-spectrum β-lactamase (ESBL)producing organisms were included in the study. The rates of appropriate carbapenem prescription were 61% (n = 41) in patients aged 65-84 years and 89% (n = 31) in those aged ≥ 85 years. Patients aged ≥ 85 years were significantly more likely to receive carbapenem than their younger counterparts. After propensity score matching, 65 patients were assigned to two groups based on age (65-84 years or ≥ 85 years). Multivariate regression analysis showed that other sites of infection had a positive association with 30-day mortality (odds ratio [OR], 27.50; 95% confidence interval [CI], 2.90-260.00) and biliary tract infection tended to have a positive association with 30-day mortality (OR, 8.90; 95% CI, 0.88- 89.90) compared with urinary tract infection. However, an age ≥ 85 years was not associated with 30-day mortality. Elderly patients aged ≥ 85 years were more likely to be treated with carbapenem; however, old age was not associated with 30-day mortality when bacteremia was caused by ESBLproducing organisms. These results may help clinicians justify withholding carbapenem in patients aged ≥ 85 years.