What if a patient does not have enough clinical criteria to meet the clinical case definition of KD but I am still worried my patient might have this disease? Does incomplete KD exist?
Yes, “incomplete KD” does exist. The clinical case definition of KD does not identify all children with the disease. Up to 10%–25% of patients with KD do not meet the full clinical criteria of KD at diagnosis. This is particularly true for infants aged <6 months who may present with only fever. Patients diagnosed with KD whose signs and symptoms do not fulfill the clinical case definition are diagnosed with “incomplete KD”. The American Heart Association has published an algorithm for the evaluation of children with suspected incomplete KD. Using this algorithm, children with fever for >5 days and at least two clinical diagnostic criteria or infants with fever for >7 days without an alternative diagnosis should have inflammatory markers (C-reactive protein [CRP] and erythrocyte sedimentation rate [ESR]) obtained. If the CRP >3.0 mg/dL or ESR >40 mm/hour, then “other laboratory studies” should be performed to look for abnormalities that commonly occur in KD: anemia for age, white blood cell (WBC) count >15,000/mm 3 , platelets >450,000/mm 3 , albumin <3 g/dL, elevated alanine aminotransferase, or urine WBC >10/HPF). Additionally, an echocardiogram (ECHO) should be obtained. If three or more of the “other laboratory studies” abnormalities are identified or the ECHO has positive findings, then a diagnosis of KD should be made and the patient should be treated.
