Evidence Based Strategies: Kawasaki Disease
Kawasaki disease (KD) is an acute vasculitis, primarily affecting the coronary arteries, and remains the leading cause of acquired heart disease in children in developed countries. In the United States, the incidence of KD is approximately 18-25 cases per 100,000 children <5 years old. The exact etiology of KD remains unknown but is thought to be the result of abnormal immune responses to an infectious and/or environmental trigger. Early recognition and treatment are especially important because 25% of untreated children develop coronary artery dilation or aneurysms. Prompt recognition and treatment with intravenous immunoglobulin (IVIG) reduce this risk to <5%.
Complete (typical or classic) KD is defined as fever for five days or more (first calendar day of fever is day 1) plus at least four of the five principal features:
- Bilateral nonexudative conjunctival injection
- Polymorphous rash (e.g., maculopapular, diffuse erythroderma, or erythema multiforme-like)
- Cervical adenopathy (typically unilateral)
- Oral mucosal changes (e.g., strawberry tongue, erythema of oral and pharyngeal mucosa, or erythematous, cracked lips)
- Extremity changes (e.g., erythema of the palms and/or soles or edema of the hands or feet)
The clinical features are generally not all present at the same time; therefore, a careful review of prior signs and symptoms during the illness aids in making the diagnosis.
Incomplete KD occurs when patients meet fever criteria, have two to three physical findings and specific laboratory findings. Children <12 months may present only with prolonged fever, requiring a high index of suspicion. These children may experience delays in diagnosis, resulting in development of coronary artery abnormalities. KD can mimic many illnesses, including adenovirus, scarlet fever, toxic shock syndrome, tickborne illness and measles, so clinicians should have a broad differential diagnosis.
Initial laboratory evaluation should include a complete blood count (CBC) with differential, basic metabolic profile (BMP), erythrocyte sedimentation rate (ESR), C-reactive protein (CRP), clean catch urinalysis (UA), and liver function tests (LFTs). In addition to elevated CRP and/or ESR, laboratory abnormalities such as normocytic anemia, leukocytosis, thrombocytosis, hypoalbuminemia, elevated alanine transaminase (ALT), and sterile pyuria may assist with making the diagnosis in children presenting with incomplete KD, but they are nonspecific. Any child meeting criteria for KD or for whom a diagnosis of incomplete KD is being considered should undergo echocardiography to evaluate the coronary arteries. The proximal left anterior descending artery and the proximal right coronary artery are the most common locations for coronary artery aneurysms. Aneurysm is defined as a coronary artery size z-score ≥2.5. It is important to have an accurate weight and height for these patients as the z-score is based on body surface area.
Once KD is diagnosed, standard treatment consists of 2 g/kg of IVIG, administered over eight to 12 hours and ideally within the first 10 days of illness. In addition to IVIG, moderate-dose aspirin (40-50 mg/kg/day divided q6) is used until the patient is afebrile for 48 hours followed by low-dose aspirin (3-5 mg/kg/day) and continued until the patient has no evidence of coronary changes at four to six weeks after illness onset. Some children may require additional therapies depending on the degree of coronary artery involvement or if they have refractory KD, defined as the persistence or recurrence of fever >36 hours after the completion of IVIG.
Measles, mumps, and rubella and varicella vaccines should be deferred for 11 months after IVIG infusion, as IVIG may reduce the vaccine effectiveness. Long-term management begins at the end of the acute illness (approximately four to six weeks after fever onset), and prognosis is determined by the initial and current level of coronary artery disease. A long-term management algorithm based on risk stratification developed by the American Heart Association outlines recommendations for assessment and counseling for patients with a history of KD. The overarching goals are to prevent thrombosis and myocardial ischemia while maintaining optimal cardiovascular health. Patients with no coronary artery changes at any stage of the illness have similar risks for clinical cardiac events to those without KD and can be discharged from cardiology anywhere between one and 12 months after acute illness. Recommendations regarding activity restrictions and reproductive counseling are dependent on coronary artery dimensions and anti-coagulant/anti-platelet medication regimen. Cardiology will dictate necessity and timing of follow-up imaging for KD patients. Any patient with history of aneurysms during their illness should be followed by cardiology.
For more information about the diagnosis and treatment of KD, please visit the Kawasaki Disease Clinical Pathway found here:
Kawasaki Disease - Children's Mercy
Reference:
- McCrindle BW, Rowley AH, Newburger JW, et al. Diagnosis, treatment, and long-term management of Kawasaki disease: a scientific statement for health professionals from the American Heart Association. 2017;135:e927-e999. doi:10.1161/CIR.0000000000000484