Reduced IgG2 with thrombocytopenia predicts mortality in patients with influenza pneumonia

Abstract

Background: Thrombocytopenia is a common disorder during influenza that is related to high mortality.

Objectives: A prospective study was performed to investigate the association of immunoglobulin subclass changes accompanying incident thrombocytopenia with clinical outcomes in patients with severe influenza.

Methods: 96 influenza patients were recruited and divided into two groups, patients with thrombocytopenia (n = 30) and patients without thrombocytopenia (n = 66). Plasma microarrays were used for quantitative analysis of immunoglobulins. The endpoint was 28-day mortality. Continuous platelet count, d-dimer, level of each Ig subclass and other variables were compared between the two groups. Kaplan-Meier curve was taken to analyze the 28-day survival rate of the two groups and Cox regression analysis was performed to identify variables independently associated with 28-day mortality.

Results: Patients with thrombocytopenia had significantly high values of d-dimer at admission and when platelet lowest with high SOFA score. Their IgA2, IgG2, and IgG4 values were also lower than those without thrombocytopenia. Patients without thrombocytopenia had a higher 28-day survival rate than those in the thrombocytopenia group. In the multivariate Cox regression model, age (HR = 1.036, 95%CI = 1.011-1.062), IgG2 (HR = 0.990, 95%CI = 0.982-0.998), platelet minimum within 28 days (HR = 0.991, 95%CI = 0.982-0.999) and d-dimer when platelet lowest (HR = 1.091, 95%CI = 1.047-1.137) were independently related to 28-day mortality.

Conclusion: Decreased IgG2 may be associated with thrombocytopenia. A coexistence of thrombocytopenia, IgG2 reduction and d-dimer elevation may improve the accuracy of mortality prediction in patients with influenza pneumonia.

Keywords: IgG2; Influenza; Prediction; Thrombocytopenia.