Serum C-reactive protein levels in patients with Kawasaki disease: from the results of nation-wide surveys of Kawasaki disease in Japan.

Thirteen nation-wide epidemiological surveys of Kawasaki disease have been carried out successively since 1970 in Japan. In the latest survey, questionnaires on serum C-reactive protein (CRP) levels of the patients were included to clarify whether serum CRP levels could be available for the diagnosis and prediction of prognosis. A questionnaire from and diagnostic guidelines for Kawasaki disease were sent to all paediatric departments of hospitals with 100 or more beds throughout Japan, and information including maximal serum CRP levels was obtained on patients with Kawasaki disease diagnosed during the 2-year period from January 1993 to December 1994. Of the 11458 patients diagnosed during the 2-year period, maximal serum CRP levels were reported in 11040 patients (96.4%). The values of maximal serum CRP were higher in the age groups < 6 months and > 2 years. The mean value and the distribution of serum CRP levels in-suspected cases were lowest among the three diagnostic categories and this difference among diagnostic categories was highly significant in the age groups 6 M-1 Y and 1-2 Y. The proportion of patients with cardiac sequelae increased with serum CRP levels in each age group. The mean value and the distribution of serum CRP levels of the patients with cardiac sequelae was higher than those without it and this difference between cardiac prognoses was outstanding in the age groups 6 M-1 Y and < 6 M. The Receiver/Response Operating Characteristic (ROC) curve for maximal serum CRP levels in Kawasaki disease revealed that accuracy of maximal serum CRP levels for prediction of cardiac sequelae was highest in the age group 6 M-1 Y. A large-scale observation and analysis of serum CRP levels of the patients with Kawasaki disease revealed age-dependent relationships among maximal serum CRP levels, diagnostic categories and prognosis. Serum CRP levels may be helpful for the prediction of prognosis with the consideration of age.