Medicine is a personal and ever changing science where providers of medical care have a responsibility to use the most recent and reliable information to guide their patients. Curbside allows medical providers to create and distribute clinical pathways to improve the care provided at their institutions. However, there is the constant potential for human error, changes in medical sciences or patient specific variables that may not be taken into account in these pathways. Therefore, Curbside cannot warrant that the information contained in these resources is accurate or complete and are not responsible for any errors or omissions or for the results obtained from the use of this information. All users of Curbside should confirm the information provided here with other trusted sources and consult with expert health providers before making any health care decision.
Kawasaki disease (KD) is a common vasculitis of childhood with unknown etiology. In the United States it has an incidence of 20 per 100,000 for all children younger than five years. However, it's incidence is very dependent on geographic location, age, gender, genetics and ethnicity.
KD affects medium sized arteries in the body, with the most profound and long term effects on the coronary arteries. Although the etiology remains unknown, many factors point to KD occurring as the result of an infectious or post-infectious process (ex. KD can occur in epidemics). Of note, KD if left untreated is a self-limiting illness with average fever length of 12 days. However, treatment may drastically decrease the risk of cardiac complications.
As KD does not have a known etiology or diagnostic test, diagnosis is made with the presence of signs of systemic inflammation (fever) in combination with mucocutaneous inflammation (primary supportive criteria). KD may present in a wide variety of forms (even without fever in patients with other signs of KD). However, this pathway uses the criteria of at least 5 days of fever to be included. Four or more of the primary criteria qualify a patient for the classical diagnosis of KD. Two to three criteria places the patient into the situation of incomplete Kawasaki disease.
KD patients may present with many other complaints as well given the systemic nature of the inflammation. A high clinical suspicion is needed, especially in patients with more than 5 days of fever.
It should be noted that the classical KD criteria where created prior to the understanding of the association between KD and cardiovascular disease and were not developed to capture all patients with potential for cardiovascular complications. Up to 10 percent of patients who progress to coronary artery aneurysms never meet the criteria for KD.
The clinical diagnosis of KD is not 100% sensitive with up to 10 percent of patients who went on to develop coronary artery aneurysms never meeting clinical criteria. This entity is referred to as incomplete KD and is more common in infants and adults presenting with KD. The most common missing criteria in patients diagnosed with incomplete KD are:
In order to identify patients at risk for coronary artery aneurysms, but who do not reach complete criteria for KD, the American Heart Association and the American Academy of Pediatrics developed a clinical pathway which is mirrored in the pathway shown here. This pathway uses laboratory studies and echocardiography to aid in the diagnosis of these patients and their need for treatment.
Given the complexity of diagnosis and multiple overlapping diagnoses, the provider may consider consultation with pediatric or rheumatologic experts in the workup of these patients.
Echocardiography should be performed soon after the diagnosis of KD (including incomplete KD) to assess for coronary artery aneurysms and other cardiac abnormalities associated with KD. This will also provide a baseline for future imaging that will be required 2 to 6 weeks later. One in five patients with untreated KD will go on to develop coronary artery aneurysms. ECG may show some changes associated with coronary artery aneurysms, but is not routine recommended as echocardiography is highly sensitive and will need to be performed in all patients.
Intravenous Immunoglobulin (IVIG) is the mainstay treatment of KD and has been shown to be highly cost-effective. It works by decreasing the systemic inflammatory response intrinsic to KD and limiting the likelihood of cardiac complications. It should be given as a single infusion over 8 to 12 hours at a dose of 2g/kg. Patient's maximally benefit if IVIG is given within day 7-10 of fever onset. If the diagnosis is made after day 10, IVIG still may provide benefit.
Aspirin is recommended in all patients with KD given its antiplatelet and anti-inflammatory effects. It is unclear if aspirin has any effects on coronary artery aneurysms (CAA), but since all IVIG studies that showed decreased incidence of CAA included aspirin, this question as yet cannot be answered (although with retrospective data analysis benefit from aspirin appears unlikely).
The regimen recommended for KD involves a high dose aspirin until the patient has been fever free for 48 hours and then low dose aspirin for 2-3 months. It has been associated with rare complications such as salicylate toxicity and Reye's syndrome, however, the regimen recommended has been optimized to provide maximum benefit with minimum risk of these complications.
10 to 15 percent of patients treated for KD will have return of fever within 48 hours. Generally, refractory KD is suspected with fever (of any magnitute) returns after 36 hours until 2 weeks after the treatment for KD has begun. These patients have an increased risk of developing coronary artery abnormalities if not retreated with IVIG.
Providers should be alert for other causes of persistant fever, including missed infectious diagnosis, macrophage activating syndrome (associated with KD) or other rheumatologic disease processess.
Several other agents have been found useful in patients with refractory KD, however they appear to not significantly decrease the risk of coronary artery abnormalities in patients responsive to IVIG. The most commonly studied (steroids) have shown benefit in patients resistant to IVIG. Steroids are not routinely recommended for initial treatment of patients with KD. Given the complexity and potential side effects of these treatments, an expert in KD (rheumatology, ID, etc.) should be consulted prior to initiating these modalities.
Studies show no differences in clinical presentations or outcomes in children with KD stratified according to positive or negative respiratory viral PCR testing.