Kawasaki disease with low C-reactive protein levels

Kawasaki disease (KD) is an acute febrile systemic vasculitis that primarily affects children, and coronary artery lesions (CALs) are severe complications. Clinical features and outcomes of patients with KD associated with low serum C-reactive protein (CRP) levels (< 3.0 mg/dL) before initial treatment remain unclear. The objective of this retrospective study was to elucidate the clinical features and outcomes of patients with KD and low serum CRP levels. Data were included from 220 patients with KD who underwent acute-phase treatment from January 2009 to February 2021 in our department. Patients were divided into low group (n = 50) and high group (n = 170) according to serum CRP levels before initial treatment. The rates of incomplete KD (48.0% vs. 10.6%, P < 0.001) and serum albumin levels (g/dL) before initial treatment (median 3.60 vs. 3.30, P < 0.001) were significantly different between the groups. The rate of patients who required intravenous immunoglobulin (IVIG) therapy was significantly lower in the low group compared to the high group (74.0% vs. 97.1%, P < 0.001). However, the rates of initial IVIG therapy resistance (10.8% vs. 25.5%, P= 0.055) and CALs (2.0% vs. 4.7%, P= 0.475) were similar between the groups. No patient in the low group experienced CALs one month after KD onset. The severity of the disease in patients with KD and low CRP levels was milder than in those with high CRP levels.