Introduction: The standard dose of intravenous immunoglobulin (IVIG) as initial therapy for patients with Kawasaki disease (KD) is generally 2 g/kg. In our hospital, the initial IVIG dose for patients with KD is 1 g/kg, which is augmented according to treatment response, and therapy is changed to plasma exchange (PE) if IVIG therapy over 6 g/kg is ineffective. To date, various factors and scoring systems for predicting IVIG resistance have been reported. We evaluated consecutive urinary β2 microglobulin to creatinine ratio (β2MG/Cr) data as a possible predictive factor of IVIG therapy resistance.
Objectives: To clarify whether urinary β2MG/Cr is an effective predictive factor for IVIG therapy resistance.
Methods: We retrospectively reviewed the data of all patients with KD who underwent IVIG therapy at a dose of over 6g/kg in our hospital from January 1997 to January 2014. Patients with recurrent KD were excluded from the study. Patients were divided into two groups for analysis, those who did and did not require PE. Factors including urinary β2MG/Cr were compared across the two groups. We used the peak urinary β2MG/Cr of each patient in the course of the disease.
Results: There were 713 patients with KD who were treated in our hospital from January 1997 to January 2014. There were 28 patients without recurrent KD who underwent IVIG therapy over 6g/kg. IVIG was successful in 24 patients (non-PE group), and 4 patients required PE (PE group). Urinary β2MG/Cr was not measured in only one patient of the non-PE group. Urinary β2MG/Cr significantly higher in the PE group (median 119,228 μg/gCr, 69,286-234,290 μg/gCr) compared to the non-PE group (median 12,270 μg/gCr, 1,981-210,647 μg/gCr) (p=0.001, t-test). Urinary β2MG/Cr exceeded 100,000 μg/gCr in 4 % (1 of 23) of the PE group and 75 % (3 of 4) of non-PE group. There were temporarily coronary artery lesions (dilation or aneurysm) in 57 % (13 of 23) of the non-PE group and 75 % (3 of 4) of the PE group. Coronary artery lesions regressed in all patients.
Conclusion: Our study suggests that urinary β2MG/Cr measurement is a useful non-invasive test for predicting IVIG resistance.