CRP and infection: Considering severe infections with CRP > 15 mg/l and necessity for inpatient treatment for intravenous antibiotics we see a significant difference of 0.057 ± 0.063 events per month in the eESS group compared to 0.189 ± 0.395 events per month in the non-sinus surgery group (p = 0.015) (Fig. 3).