Evaluation of humoral immune response to nosocomial pathogen and functional status in elderly patients with sepsis.

The clinical significance of humoral immune response to nosocomial pathogens and functional status in elderly patients with sepsis is not clear. We evaluated the humoral immune to nosocomial pathogens and the effect of functional dependencies on clinical outcomes among elderly patients with sepsis. This study prospectively enrolled patients aged ≥65 years with sepsis from September 2011 to May 2012 at a 2000-bed university hospital. The data including CD4 and CD8 T-cell count, functional status by measuring basic activities of daily living (ADL) and instrumental activities of daily living (IADL) were collected for all patients. In addition, the collected blood samples were analyzed for serum antibody levels against nosocomial pathogens using an ELISA. During the study period, 72 patients (38 males) treated with sepsis were enrolled. The all-cause in-hospital mortality rate was 16.7% (12/72). The mean CD4/CD8 T-cell ratio was significantly lower in nonsurvivors than in survivors (1.08 ± 0.72 vs. 1.93 ± 1.42, P=0.003). Serum antibody titers to Acinetobacter baumannii, Klebsiella pneumonia, Stenotrophomonas maltophilia, and Enterococcus faecalis were statistically higher in nonsurvivors than in survivors. On multivariate analysis, the IADL score was independently predictive of mortality in elderly patients with sepsis (odds ratio 1.410, 95% confidence interval 1.007-1.975, P=0.046). These results suggest that IADL scores could be used as predictors to identify elderly patients with a poor prognosis of nosocomial infections.