Cost-effectiveness analysis of infliximab for the treatment of Kawasaki disease refractory to the initial treatment: A retrospective cohort study.

BACKGROUND: Infliximab (IFX) treatment is approved in Japan for health insurance coverage in patients with Kawasaki disease (KD). This study aimed to compare the cost-effectiveness of IFX and other therapeutic strategies for KD refractory to initial treatment, including intravenous immunoglobulin (IVIG), steroids, immunosuppressants, and plasma exchange therapy. METHODS: This multicenter, retrospective cohort study utilized data from the public medical insurance system of Japan. The target population included those who received treatment for KD between April 2012 and March 2019. Eligibility criteria were as follows: 1) initial onset of KD, 2) age < 15 years at onset, and 3) administration of 3rd line treatment if the 1st line treatment was IVIG alone or 2nd line treatment if the 1st line treatment was a combination of IVIG and steroids, in accordance with Japanese guidelines (2012). Those with KD-related cardiovascular complications before admission and those with congenital cardiac disease were excluded. The primary outcome was cost-effectiveness, which was calculated based on the number of admission events per annum divided by medical expenses per annum (times/10,000 US dollars). The Wilcoxon test was applied to analyze the difference in cost-effectiveness between patients who had received IFX and those who had not. RESULTS: Among 1267 patients with KD, 25 received IFX treatment, while 206 received another treatment after the disease was designated refractory to initial treatment. The frequency of steroid use during initial IVIG treatment (a predictor of severity) was higher in the non-IFX group than in the IFX group (70.4% vs. 32.0%, p < 0.001) but became comparable after propensity-score matching. Our analysis indicated that IFX was more cost-effective than other treatments [1.04 (0.86, 1.34) vs. 1.38 (1.03, 1.79) (times/10,000 US dollars), p = 0.006]. CONCLUSIONS: IFX treatment may be more cost-effective than non-IFX treatment for patients with KD that is refractory to initial treatment.