Fig. 3From: Trends in use and impact on outcome of empiric antibiotic therapy and non-invasive ventilation in COPD patients with acute exacerbationImpact of empiric antibiotic therapy on VAP and ICU mortality: analysis with Kaplan–Meier survival method shows that empiric antibiotic therapy was associated with a decrease in VAP occurrence (b) (log rank test, p < 0.001), but had no effect on mortality (a) (log rank test, p = 0.793)Back to article page