Intravenous Immunoglobulin and Mortality in Pneumonia Patients With Septic Shock: An Observational Nationwide Study

Background. The role of intravenous immunoglobulin (IVIG) as an adjunctive treatment for severe sepsis remains controversial. We hypothesized that IVIG could be effective for treating pneumonia patients who have septic shock. Methods. Mechanically ventilated pneumonia patients with septic shock were identified in the nationwide Japanese Diagnosis Procedure Combination inpatient database from 1 July 2010 to 31 March 2013. The effect of IVIG use on 28-day mortality was evaluated using propensity score and instrumental variable analyses. Results. Eligible patients (n = 8264) from 1014 hospitals were divided into an IVIG group (n = 1324) and a control group (n = 6940). Propensity score matching created a matched cohort of 1045 pairs with and without IVIG treatment. There was no significant difference in 28-day mortality between the IVIG and control groups in the unmatched analysis (37.8%, 501/1324 vs 35.3%, 2453/6940; difference, 2.5%; 95% confidence interval [CI], -.3 to 5.3) or the propensity score-matched analysis (36.7%, 383/1045 vs 36.0%, 376/1045; difference, 0.7%; 95% CI, -3.5 to 4.8). Logistic regression analysis did not show a significant association between IVIG use and 28-day mortality in propensity score-matched patients (1.03; 95% CI, .86 to 1.23). Analysis using the pattern of hospital IVIG use as an instrumental variable found that IVIG use was not associated with a reduction in 28-day mortality (difference, -3.1%; 95% CI, -13.2 to 7.0). Conclusions. In this large retrospective nationwide study, we found that there may be no significant association between IVIG use and mortality in mechanically ventilated pneumonia patients with septic shock.