Clinical and epidemiologic characteristics of patients referred for evaluation of possible Kawasaki disease. United States Multicenter Kawasaki Disease Study Group.

STUDY OBJECTIVES: (1) To determine those diseases that most often mimic Kawasaki disease (KD) in the United States. (2) To examine the physical findings and laboratory studies that influenced experienced clinicians to exclude the diagnosis of KD. (3) To compare epidemiologic features of patients with KD and patients referred for evaluation of possible KD in whom alternative diagnoses were established. DESIGN: Case comparison study. SETTING: Seven pediatric tertiary care centers. PATIENTS: Consecutive sample of 280 patients with KD and 42 comparison patients examined within the first 14 days after onset of fever. MEASUREMENTS AND MAIN RESULTS: (1) Infectious diseases, particularly measles and group A beta-hemolytic streptococcal infection, most closely mimicked KD and accounted for 35 (83%) of 42 patients in the comparison group. (2) The standard diagnostic clinical criteria for KD were fulfilled in 18 (46%) of 39 patients in whom other diagnoses were established. (3) Patients with KD were significantly less likely to have exudative conjunctivitis or pharyngitis, generalized adenopathy, and discrete intraoral lesions, and more likely to have a perineal distribution of their rash. The patients with KD were also more likely to have anemia and elevated erythrocyte sedimentation rate; leukocyte count less than 10 X 10(3)/mm3 and platelet count less than 200 X 10(3)/mm3 were significantly less prevalent in patients with KD. (4) Residence within 200 yards of a body of water was more common among KD patients. CONCLUSIONS: (1) Measles and streptococcal infection should be excluded in patients examined for possible KD. (2) Laboratory studies that may be useful in discriminating patients with KD from those with alternative diagnoses include hemoglobin concentration, erythrocyte sedimentation rate, and serum alanine aminotransferase activity. (3) Residence near a body of water may be a risk factor for the development of KD.

Interpretation of IgG subclass values: a comparison of two assays.

Because we have noted discordant results in the measurement of IgG subclass concentrations by means of a widely available commercial radial immunodiffusion (RID) kit in comparison with an enzyme-linked immunosorbent assay (ELISA) developed at the Centers for Disease Control (CDC), we conducted in a blinded manner a comparison of the two assays, using sera from 48 healthy children. The correlation coefficients between the assays were 0.92, 0.82, 0.93, and 0.86 for the IgG1, IgG2, IgG3, and IgG4 assays, respectively. However, the RID assay assigned lower values for IgG1 and IgG4 determinations than the ELISA did. Furthermore, the "normal lower range values" provided by the RID assay were higher for each IgG subclass. When the sera from the healthy control subjects were analyzed with the RID assay, 12 (25%) of 48 subjects had values below the normal range for at least one subclass measurement. In contrast, with the CDC ELISA, all values were within the 95% confidence limits determined for the CDC ELISA. We suggest that age-specific normal limits be established with the use of sera from many healthy subjects for any assay measuring IgG subclass concentrations. As new groups of immunodeficiencies are defined and potential therapies are advocated, careful attention to assay standardization will result in a clearer delineation of these disease groups and of their response to treatment.