Low levels of immunoglobulin G in patients with sepsis or septic shock: a signum mali ominis?

Introduction

The role of intravenous immunoglobulin therapy in patients with sepsis and septic shock is still controversially discussed. In a retrospective analysis of the data from the SBITS-trial [1] we investigated whether the initial level of serum IgG on admission to the hospital in patients with sepsis and septic shock (before the first administration of the first dose of intravenous immunoglobulins) could be seen as a prognostic parameter for the primary outcome, lethality on day 28, or the secondary endpoints, lethality on day 7 or on the ICU.

Methods

A total of 543 were included in the trial: the patients were divided into four groups (quartiles) based on the 25th, 50th and 75th percentiles of their initial level of IgG on admission to the hospital. The first group contained 140 patients with a range in the IgG serum level up to 6.1 g/dl. The second and third groups contained 134 patients and 136 patients, respectively, the immunoglobulin G levels were greater than 6.1 g/dl to 8.4 g/dl and greater than 8.4 g/dl to 11.9 g/dl. The fourth group containing 133 patients had IgG levels higher than 11.9 g/dl. In a logistic regression model we adjusted for potential confounders (that is, sex, age, APACHE II score, presence of shock on admission).

Results

On basis of this model we could show that lethality between the first and second groups did not differ significantly with the lethality in the third (reference) group with physiologic levels of IgG on day 0. Surprisingly the lethality of the fourth group, with IgG levels higher than 11.9 g/dl, was significantly higher compared with the reference quartile (OR 1.69, CI 1.01 to 2.81, P = 0.047).

Conclusions

Our post-hoc analysis did show no prognostic relevance of a low level of serum IgG on admission to hospital for the 543 patients with sepsis and septic shock. Thus the initial serum level of IgG seems to be of no aid in making the decision to initiate therapy with intravenous immunoglobulins for these patients. Whether a high level of serum IgG on admission is an independent risk factor for an increased lethality in critically ill patients, as shown in our analysis, needs to be investigated in further studies.