engleski

Intensive care unit acquired bloodstream infections – impact of the patient`s age

ABSTRACT Introduction: Nosocomial infections are the rising problem of modern medicine. Among them, the intensive care unit (ICU) acquired infections are the major issue of concern because of their high incidence and excessive negative impact on morbidity, mortality and overall hospital costs. In correlation to progressive aging of population, the rate of patients ≥65 yrs treated in ICU is on the increase. Little is known about the relationship between older age and ICU- acquired infections. Objective: To assess the relationship between older age and risk for acquisition of ICU acquired bloodstream infections (BSI), determine their epidemiology and the impact of the patient`s age on the clinical outcome. Design: Retrospective analysis of prospectively collected cohort of ICU patients. Setting: ICU of the University Hospital for Infectious Diseases, Zagreb. Patients: Mechanically ventilated (MV) infectious disease patients of both sexes ≥18 yrs, treated in ICU ≥48h from 1994 -2008. Methods: standard tests for uni- and bivariate analyses, multivariate analysis (logistic regression), „propensity score“ calculation. Outcome variables: primary: acquisition of BSI ; secondary: duration of ICU stay, overall and 28-day survival rate in ICU. Results: Of 1093 included patients 46.6% were ≥65 yrs. The elderly patients had higher rate of BSI (26.1 vs. 21.1%, p=0.484) and higher mortality rate (52.7 vs.42.8, p=0.0010). Among patients with BSI 52% were ≥65 yrs, 53.1% were female, and 59.5% had CNS infection. The patients with BSI had lower age-adjusted APACHE II score (mean 15.3 vs. 17.7, p=<0.0001) and higher GCS (mean 11.2 vs. 10.2, p=0.0005), longer insertion of CVC (mean: 25.6 vs. 10.9 days, p=<0.0001), longer duration of MV (mean: 28.3 vs. 10.1 days, p=<0.0001), but they had higher survival rate (59.8% vs. 50.3%, p= 0.0079). Multivariate analysis shoved no correlation between age and BSI acquisition (OR:0.992, 95%CI: 0.712-1.381). Because of imbalance between groups, the propensity scores for acquiring BSI were calculated and further analysis of clinical outcomes was performed on 212 adjusted pairs of the patients. Although showing significantly longer ICU stay, clinical outcome analyses suggest a tendency of higher survival rate among patients ≥65 yrs with BSI (p=0.0686) and showed higher 28-days survival among them (p=0.047). The etiology of BSI was similar in both observed age-groups (p=0.4940) ; out of a total of 353 episodes of BSI in 256 patients, 32.0% were caused by non-fermenting gram-negative bacteria, 24.1% by enterobacteria, 18.1% by gram-positive bacteria, 17.6% were polymicrobial, 7.1% caused by Candida and 1.1% by other bacteria. Of 353 episodes of BSI, 14.2% were caused by ESBL and third-generation cephalosporin-resistant bacteria, 9.3% by MRSA, 1.1% by ampicillin-resistant enterococci, 4.5% by multidrug-resistant and 3.4% by carbapenem-resistant non-fermenting gram-negative bacteria. Conclusions: Elderly patients represented a high proportion among observed patients. Although the proportion of patients with BSI and the overall mortality rate was higher among patients ≥65 yrs, multivariate analysis showed no correlation between age and BSI acquisition. Clinical outcome analysis showed a significantly longer ICU stay, but better overall and 28-day survival rate among patients ≥65 yrs with BSI. No differences were found in etiology and resistance pattern of BSI episodes between the observed age-groups.

intensive care unit; mechanical ventilation; nosocomial bloodstream infections; elderly; etiology; outcome

nije evidentirano