Severe sepsis is still associated with a mortality of 29% [1]. Sepsis mortality is highest in elderly patients [1]. Another factor, which is related to outcome in sepsis is the extent of complement activation [2]. The aim of this study was to evaluate complement activation in relation to age in severe septic patients.

This observational study was performed in 20 patients with severe sepsis (SOFA-Score = 9 ± 3) and grouped according to age: = 60 years ('adult', n = 10) and > 65 years ('elderly', n = 10). Complement proteins Bb, C3a, C4d were performed by ELISA technique. C1-Inhibitor (C1-Inh) activity was measured by Berichrom^® C1-Inactivator, and C1-Inh protein concentration by NOR-Partigen^®. To compare values at onset of severe sepsis with those on the 8 th day Friedman test with post-hoc Wilcoxon test was performed. Data are presented as median and range. ^*P < 0.05 was considered significant.

Activation of the classical pathway of complement was found to be more marked in adult patients than in elderly. Thus, our results suggest age-related differences in the complement activation in severe sepsis.