Purpose: Few studies have compared the effects of low-concentration (5%) and high-concentration (10%) intravenous immunoglobulin (IVIG) preparations for patients with Kawasaki disease (KD) in the acute phase. The purpose of this study was to compare outcomes between low-and high-concentration IVIG preparations in children with KD, using a national inpatient database in Japan.Method: We used the Diagnostic Procedure Combination database to identify patients with KD treated with IVIG from April 2012 to March 2020. We identi ed those receiving high-and low-concentration IVIG preparations as an initial treatment. The outcomes included the proportions of patients with coronary artery abnormalities (CAAs) and IVIG resistance, length of stay, and medical costs. Propensity scorematched analyses were conducted to compare the outcomes between the two groups. Instrumental variable analyses were performed to con rm the results.Result: We identi ed 48,046 patients with KD and created 4:1 propensity score-matched pairs between the low-and high-concentration IVIG groups. There was a signi cant difference in the percentage with IVIG resistance between the two groups (20.6% vs 24.1%; risk difference, 3.5% [95% con dence interval, 2.3-4.7]; p < 0.001). However, there was no signi cant difference in CAAs (1.6% vs 1.6%; risk difference, 0.013% [95% con dence interval, −0.34 to 0.37]; p = 0.953). The instrumental variable analyses showed similar results.Conclusions: The proportion of CAAs did not differ signi cantly between those receiving low-and highconcentration IVIG. To con rm the results of this study, prospective studies adjusting for duration of IVIG administration and duration of observation are needed.
BackgroundWhat is Known:-For treatments of Kawasaki Disease in acute phase, intravenous immunoglobulin (IVIG) has been the most recommended to reduce fever early and prevent complications of coronary artery abnormalities. There are two types of IVIG preparations, low-concentration (5%) IVIG and high-concentration (10%) IVIG. However, few studies have performed comparisons to determine which preparation of IVIG is superior.What is New:-The present ndings suggest that the proportion of coronary artery abnormalities did not differ signi cantly between those receiving low-and high-concentration IVIG.