Falling Through the Cracks: The Current Gap in the Health Care Transition of Patients With Kawasaki Disease: A Scientific Statement From the American Heart Association

The incidence of KD, the most common cause of acquired heart disease in children, is highest in Japan, where by 10 years of age, >1 in 100 children have a history of KD, with 1 in every 65 boys and 1 in every 82 girls diagnosed with KD.^{8, 9} In the United States, despite some seasonal variations in KD, incidence rates are 20 to 25 per 100 000 children <5 years of age, >10 times lower than that in Japan. Despite a lower incidence, it is estimated that 1 in 1600 Americans will have a history of childhood KD by 2030.¹⁰ KD is reported in >60 countries, with increasing incidence in many parts of the world.^{11, 12, 13, 14} The mortality rate in KD is generally <1%, likely an underestimation given missed cases and that this is not a reportable disease in many parts of the world.^{13, 15} However, some patients experience significant morbidity related to the development of coronary artery aneurysms, defined by the American Heart Association as Z‐score (internal diameter adjusted for body surface area) ≥2.5.¹⁶ Coronary artery aneurysms are classified by the patient’s maximal coronary Z‐score as small (Z‐score ≥2.5 and <5.0), medium (Z‐score ≥5.0 and <10), and large or giant (Z‐score ≥10).¹⁷ About 20% of patients with KD develop transient coronary artery dilatation (Z‐score ≥2 and <2.5), and up to 5% develop medium or large coronary artery aneurysms.¹⁸ In a comparative analysis of coronary artery measurements from American and Japanese patients with KD, nearly 30% of patients in the United States and 44% of patients in Japan met the cut point of a coronary artery Z‐score ≥2.5%, and 5% of patients from both countries developed coronary artery aneurysms with a maximum Z‐score ≥5.¹⁹ Extremes of age (infants and children >8 years), male sex, delayed diagnosis and treatment, and higher markers of inflammation at the time of diagnosis have been associated with increased risk of cardiovascular complications,^{20, 21, 22, 23} specifically coronary artery aneurysms.

Although coronary artery aneurysm regression is reported in 75% of patients, long‐term effects in the inflamed arterial wall remain a concern, especially in patients with KD with giant aneurysms that have not regressed. With aneurysmal remodeling or regression, there is the risk that myofibroblast proliferation can result in abnormal vascular reactivity.^{24, 25} Thrombosis and progressive stenosis of a giant aneurysm can cause ischemic heart conditions, myocardial infarction, and sudden cardiac death in up to 48% of such patients.^{16, 26}

Additional lines of study suggest that long‐term follow‐up is necessary for patients with KD and with coronary artery issues. Optical coherence tomography imaging of patients with KD with various degrees of coronary sequelae has shed new light on the vascular damage in these patients. In a series of 33 patients aged 12.0±5.4 years, lesions, such as parietal fibrosis, cellular infiltrates, intimal hyperplasia, or neovascularization, were detected even in some coronary artery segments without previous dilation by echocardiogram. Similar lesions were present in significantly higher proportions in coronary segments with persistent aneurysms, followed by segments with angiographically regressed aneurysms and segments with coronary artery dilatation but no previous evidence of aneurysms.²⁷ A recent review of mid‐term complications after acute KD in patients with documented coronary artery aneurysms was completed by the International KD Registry.²⁸ In this cohort of 1651 patients with KD, patients with coronary artery aneurysms with Z‐scores <10 were primarily risk free, with only 1 patient with an aneurysm Z‐score of 8.5 showing chronic cardiac ischemia, resulting in heart failure and death. The risk of luminal narrowing and coronary artery thrombosis in this cohort was otherwise restricted to patients with large or giant aneurysms (Z‐score ≥10). The strongest predictor of cardiac risk continues to be the extent of damage to the coronary arteries. The persistence of large coronary artery aneurysms has a high risk of complications, which does not totally exclude those with remodeled aneurysms.^{6, 29} Beyond the coronary complications, myocarditis is seen in the acute phase of KD, with myocardial function generally thought to be normal beyond the acute phase in patients who do not develop ischemic heart disease.³⁰ Nevertheless, increased left ventricle volume, decreased strain, altered diastolic parameters up to 12 months after onset of KD, and increased myocardial collagen distribution and content irrespective of the presence or the absence of coronary aneurysms suggest a possible long‐term effect on myocardial structure and function.³¹

According to the 2017 American Heart Association KD guidelines, patients with KD with no history of coronary aneurysms do not appear to be at increased risk of cardiac events in adulthood and typically do not require long‐term cardiology follow‐up.^{16, 24, 32} Patients with KD and with aneurysms, either persistent or those that have been remodeled and have decreased to a normal internal luminal dimension, should have long‐term follow‐up, with their care transitioned to an adult cardiologist once they reach adulthood, generally between the ages of 18 and 21 years.¹⁶ Most important, patients with documented and persistent moderate or large aneurysms require life‐long surveillance with yearly or biyearly assessment.¹⁶ Therefore, there remains a significant number of patients with KD who should have long‐term cardiology follow‐up into adulthood.

Transition from pediatric to adult care for these patients needs to be a process involving a deliberate and coordinated series to ensure uninterrupted care. Adult patients with KD would benefit from follow‐up with an adult cardiologist who understands both coronary artery disease as well as unique issues related to KD.

As KD typically occurs in young children, the 2017 KD guidelines laid out several educational goals that are important to discuss with parents as well as patients with KD starting at approximately age 12 years. These “knowledge goals” include: (1) review of details of their illness, including sustained complications, cardiac sequelae, any cardiac events, and related procedures; (2) the names and rationale for any diagnostic tests performed; (3) precise information on medications that are required; (4) importance and rationale behind restrictions on physical activity if any; and (5) specific symptoms or signs that warrant immediate medical attention. This information must be understood and retained by the patient, who should also understand the importance of uninterrupted life‐long cardiology care. Considerations on contraception and pregnancy of female patients warrant clarification. Later on, the small but real risk of the possibility of KD in offspring should be understood. Finally, long‐term prognosis and associated health issues should be discussed as well as preventive strategies to achieve healthy lifestyle behaviors.

“Self‐management skills” should be made apparent to the young adult with KD at the time of transfer to increase the chance of success in the HCT. Those skills include the ability to contact health care professionals, to schedule and attend appointments and tests, as well as to know when and how to access emergency care or mental health services. Other self‐caring goals are more specific, such as creating and using a portable health summary and maintaining health records and adhering to a medication regimen, including requesting prescription refills and being able to communicate independently and effectively with health care professionals.

However, despite these established objectives, there is currently no clear path for HCT in many centers that care for patients with KD. Some centers transition patients with KD to adult cardiologists, others consider adult congenital heart specialists, independently or in conjunction with KD specialists, whereas other centers delay HCT indefinitely.

In 2018, the American Academy of Pediatrics, the American Academy of Family Physicians, and the American College of Physicians jointly published the “Clinical Report: Supporting the Health Care Transition From Adolescence to Adulthood in the Medical Home.”¹ This report builds on an earlier 2011 clinical report and represents professional organizations' consensus on practice‐based implementation of HCT for all children and youth beginning in early adolescence and continuing into young adulthood.² The American Academy of Pediatrics, the American Academy of Family Physicians, and the American College of Physicians recommend a structured transition that is supported by 2 systematic reviews.^{33, 34, 35} These systematic reviews show statistically significant positive transition outcomes for youth with special needs in the areas of: (1) population health (adherence to care, self‐care skills, quality of life, and self‐reported health), (2) experience of care (increased satisfaction and reduction in barriers to care), and (3) utilization (decrease in time between last pediatric and first adult visit, increase in adult ambulatory visits, and decrease in hospital admissions and length of stay) with use of this approach. This evidence‐based structured transition incorporates the following components: planning, transfer, and integration into adult care. To accomplish these 3 components of HCT, the 2018 American Academy of Pediatrics, American Academy of Family Physicians, and American College of Physicians clinical report recommends using an approach called the Six Core Elements of HCT (Figure 1). This approach was developed by Got Transition, the federally funded national HCT center, and has been tested in a series of quality improvement learning collaboratives that demonstrated the effectiveness of an organized transition process in pediatric, family medicine, and internal medicine practices. The Six Core Elements (policy, tracking, readiness, planning, transfer of care, and transfer completion), with sample customizable tools and measurement and implementation resources (https://www.gottransition.org/six‐core‐elements/), have been widely used in primary and specialty care systems³⁶ (Figure 1). This report reiterated that HCT is not just transfer alone but that all 3 components are required and that the HCT process should start early, between the ages of 12 and 14 years.

A key starting point for improving transition is preparation of youth with KD as well as parents/caregivers for an adult model of care. This preparation includes the following elements, outlined in the Six Core Elements approach for the pediatric clinician (Figure 1).

The first core element is policy, which includes preparing an office transition guide for families, including discussion of the practice's approach to an adult model of care around privacy and consent. The second core element is tracking, which ensures that a patient is offered a transition readiness/self‐care skill assessment conducted periodically. The third core element is transition readiness. The pediatric clinician should have a standardized way of assessing the youth's self‐care skills. The fourth core element is planning, which involves creating a transition plan jointly developed with youth and families that includes preparing for decision‐making support, assembling a medical summary and emergency care plan shared with youth and families, identifying an adult cardiologist and primary care clinician, and preparing transfer information for and communication with the new clinician. The fifth core element is transfer of care, which requires engagement³⁷ during this vulnerable transition time of both the adult clinician and the pediatric subspecialist to help the young adult schedule a follow‐up appointment with the adult health care clinician within 3 to 6 months of leaving the pediatric clinician. The sixth core element is transition completion, during which the pediatric clinician confirms that the young adult has been seen by the adult clinician and facilitates obtaining patient feedback about the HCT process.

HCT preparation involving all 6 core elements is a process that evolves over several years and includes working with the adolescent's developmental stages to achieve maturity, education, and self‐management. Integrating the age of transition with the required HCT steps and elements results in an uninterrupted, longitudinal process; this process leads to the highest probability of success (Figure 2).³⁷ Just as there is a Six Core Elements package for pediatric primary care and pediatric cardiologists, there is also a Six Core Elements package for adult primary care and adult cardiologists to assist them in integrating and engaging the young adult with KD into their practice (https://www.gottransition.org/six‐core‐elements/integrating‐young‐adults/).³⁶

One of these preparation elements involves conducting a readiness or self‐care skill assessment to evaluate the young adults' understanding about their own health and how to navigate adult health care. There are several readiness assessment tools available, but none to date has been externally validated in any disease, including KD.^{38, 39, 40, 41, 42, 43, 44, 45} This means that a high score on any of the readiness assessments does not necessarily predict a successful outcome. Use of a readiness/self‐care assessment tool is primarily to start the conversation on what the young adult can do to better prepare for an adult approach to care and to an adult health care system. One aspect of transition readiness is to understand the youth's and families' perception of transition and their willingness to engage in the transition process.

Got Transition's readiness assessment tool assesses the youth's overall approach to HCT by asking 2 motivational interviewing questions: (1) How important is it to you to transition to an adult provider or to manage your own health care? (2) How confident are you in transitioning to an adult clinician or managing your own health care? These questions have a scale answer from 1 to 10, where 0 is not important or confident and 10 is very important or confident.⁴⁶ These 2 questions can assist the clinician gauge where the youth is in his or her overall readiness, letting the clinician know if the youth does not feel transition is important and whether the individual is confident in his or her ability to move forward. To further explore the importance or confidence of transitioning, more probing questions can be asked (Table 1).⁴⁷ Many adult and pediatric specialty clinicians in collaboration with patient representatives and pediatric and adult stakeholders have customized the transition readiness assessment tool and other tools from the Six Core Elements for particular diseases. Such examples include the American College of Cardiology's congenital heart disease HCT information and the American Heart Association Congenital Heart Defects Committee.^{48, 49} Similarly, a KD‐specific transition readiness assessment tool can be created for patients with KD.

HCT to an adult cardiologist is potentially difficult because of lack of exposure to KD for most adult cardiologists in training and clinical practice. The clinical issues to be managed revolve around the risk for thrombosis and stenosis of the coronary and peripheral vessels. Prevention and management of coronary thrombosis or stenosis associated with coronary aneurysms represents challenges that may differ from those seen with atherosclerotic disease. The use of statins in children with complicated KD is becoming more common but for reasons other than decreasing cholesterol.^{50, 51} However, the literature on the utility of statins in the adult with complicated KD is lacking. Because coronary pathology following KD differs from that caused by atherosclerosis, the in situ anti‐inflammatory effects of statins may be taken into consideration for adult patients with KD and with coronary artery complications.^{52, 53, 54} When complications do arise, percutaneous interventions can be challenging because of a large clot burden (that can obscure vessel size and result in undersized stenting) or dense calcification of lesions (requiring atherectomy before dilatation).⁵⁵ Surgical bypass in the setting of a moderate clot burden and good flow can lead to graft failure because of competitive flow in the native vessel. An adult cardiologist cognizant of the natural history of KD coronary aneurysms who can partner with experienced interventional cardiologists or cardiothoracic surgeons would be well suited to manage these more affected patients.

Although many adult health care centers may only see a handful of adults with KD, developing and adopting standardized practice workflows based on evidence and published guidelines can help ensure that patients with coronary artery damage from KD in childhood receive high‐quality care. With a plethora of clinical guideline publications, quality of care delivery has been closely linked to standardized practice based on evidence.^{1, 56} Over the past decade, the focus of quality has begun to shift from standardization to personalization. Delivering proactive, rather than reactive, care in a manner that is personalized and patient centered is emerging as a cornerstone to quality care.^{57, 58} For patients with KD, where genetics, environment, and behavior converge to determine outcomes, quality of care despite low patient volumes is particularly important.

Quality determinants of HCT programs can be assessed using an adapted Donabedian approach, characterizing structure, process, and outcomes related measures of patients with KD during HCT.⁵⁹ The structural components of HCT delivery need to reflect the required interdisciplinary expertise (notably, adult and pediatric care providers with on‐site interventional cardiac catheterization capabilities as well as the capacity to perform coronary artery bypass grafting by expert surgeons). This combination of expertise can most often be found in tertiary or quaternary care institutions. Process measures of quality require the ability of an adult cardiologist to prevent complications of coronary disease, anticipate the risk of coronary complications with noninvasive and invasive imaging modalities, and treat acute coronary syndromes when they occur. This hybrid expertise is vital for optimizing care delivery for the growing number of pediatric patients with KD reaching adulthood. Ultimately, quality outcomes in HCT means minimizing the care gaps that can lead to avoidable complications and adverse comorbidity related to myocardial dysfunction, including the prevention of the delayed presentation of acute myocardial infarction and sudden cardiac death. Resource allocation for HCT programs for KD, as with other conditions, depends on the critical mass of patients, the institutional priorities, competing demands on the health care system, and the ability to deliver cost‐effective health management solutions.

Like other youth with pediatric conditions that extend across the lifespan, the course of patients with KD and a history of coronary artery aneurysms has long periods of stability variably punctuated by acute but reversible deterioration.⁶ In light of the variation in the patterns of disease expression, care delivery needs to be nimble and highly responsive to patients and families as needs wax and wane throughout the longevity that survival permits. In general, HCT programs can be established using one of several models: as part of broader HCT interdisciplinary programs aimed at supporting patients with chronic conditions, as part of a single specialty care program depending on the organ affected, or as dedicated stand‐alone structures. There may certainly be barriers encountered to establishing an HCT program given the limitation of resources available in certain settings. In the absence of the ability to create a full interdisciplinary program, an alternative may be to assess a patient's readiness for transfer by evaluating the patient's understanding of the illness, medications, and rationale for certain testing starting at age 12 years, identifying an adult provider in the community who understands the complexities of KD and is willing to follow these patients, and providing that adult provider and patient with KD a medical summary that delineates key clinical issues, including the worst Z score, most recent cardiac imaging, and medications.

Although much progress has been made in designing and implementing HCTs over the past decade, there are critical gaps in knowledge about their optimal implementation and effectiveness that must be addressed in future studies. Specifically for patients with KD, areas of future study include the following: (1) evaluating the impact of HCTs from pediatric to adult health care; (2) studying transition outcomes in terms of population health (eg, adherence to care and self‐care skill development), experience of youth, young adults, families, and clinicians, and use (eg, time between last pediatric and first adult visit, adherence to adult clinician appointments, and decreased emergency department and urgent care use) and cost savings; and (3) conducting surveys of young adults about their experience with transferring and integrating into adult care.

Digital technologies can be incorporated into a variety of disease models to direct patients and families to appropriate resources in a timely manner. Their effectiveness should be the subject of future studies.^{60, 61} The life‐course health development framework was created to shift the emphasis away from disease and toward health, with the knowledge that health is a consequence of genetic, biological, and social determinants, and with the understanding that health development is an adaptive process.⁶² This is particularly relevant to patients with KD who will have largely normal lives, potentially punctuated with episodes of disease attributable to cardiac damage in childhood. Thus, the maintenance of health as an adaptive process that requires an understanding of risk management over long periods of time will lead to a more personalized approach to surveillance recommendations not only during transition of care but across the life course.

In summary, a successful HCT program for patients with KD is a multipronged approach that focuses on preparedness of the KD patient's team that is referring the patients, the patient with KD, the receiving team, and scientific societies and governing bodies (Figure 3).