Preterm birth and Kawasaki disease: a nationwide Japanese population-based study

The etiologies of Kawasaki disease

Kawasaki disease (KD) is a systemic vasculitis that affects young children and can result in coronary artery aneurysms. The etiology is currently unknown, but new clues from the epidemiology of KD in Japan, the country of highest incidence, are beginning to shed light on what may trigger this acute inflammatory condition. Additional clues from the global changes in KD incidence during the COVID-19 pandemic, coupled with a new birth cohort study from Japan, point to the potential role of person-to-person transmission of an infectious agent. However, the rising incidence of KD in Japan, with coherent waves across the entire country, points to an increasing intensity of exposure that cannot be explained by person-to-person spread. This Review discusses new and historical observations that guide us toward a better understanding of KD etiology and explores hypotheses and interpretations that can provide direction for future investigations. Once the etiology of KD is determined, accurate diagnostic tests will become available, and new, less expensive, and more effective targeted therapies will likely be possible. Clearly, solving the mystery of the etiologies of KD remains a priority for pediatric research.

Multisystem inflammatory syndrome in 1.2 million children: longitudinal cohort study of risk factors

BACKGROUND

We identified patient characteristics associated with an increased risk of developing MIS-C.

METHODS

We conducted a longitudinal cohort study of 1,195,327 patients aged 0-19 years between 2006 and 2021, including the first two waves of the pandemic (February 25-August 22, 2020 and August 23, 2020-March 31, 2021). Exposures included prepandemic morbidity, birth outcomes, and family history of maternal disorders. Outcomes included MIS-C, Kawasaki disease, and other Covid-19 complications during the pandemic. We calculated risk ratios (RRs) and 95% confidence intervals (CIs) for the association between patient exposures and these outcomes using log-binomial regression models adjusted for potential confounders.

RESULTS

Among 1,195,327 children, 84 developed MIS-C, 107 Kawasaki disease, and 330 other Covid-19 complications during the first year of the pandemic. Prepandemic hospitalizations for metabolic disorders (RR 11.3, 95% CI 5.61-22.6), atopic conditions (RR 3.34, 95% CI 1.60-6.97), and cancer (RR 8.11, 95% CI 1.13-58.3) were strongly associated with the risk of MIS-C, compared with no exposure. These same exposures were also associated with Kawasaki disease and other Covid-19 complications. However, birth characteristics and history of maternal morbidity were not associated with MIS-C development.

CONCLUSIONS

Children with pre-existing morbidity have a considerably elevated risk of MIS-C.

IMPACT

Morbidities that predispose children to multisystem inflammatory syndrome (MIS-C) are unclear. In this study, prepandemic hospitalizations for metabolic disorders, atopic conditions, and cancer were associated with an elevated risk of MIS-C. Birth characteristics and family history of maternal morbidity were not, however, associated with MIS-C. Pediatric morbidities may play a greater role in MIS-C onset than maternal or perinatal characteristics, and may help clinicians better recognize children at risk for this complication.

Roles of Oxidative Injury and Nitric Oxide System Derangements in Kawasaki Disease Pathogenesis: A Systematic Review

Kawasaki disease (KD) is an acute febrile vasculitis that occurs mostly in children younger than five years. KD involves multiple intricately connected inflammatory reactions activated by a cytokine cascade. Despite therapeutic advances, coronary artery damage may develop in some patients, who will be at risk of clinical cardiovascular events and even sudden death. The etiology of KD remains unclear; however, it may involve both genetic and environmental factors leading to aberrant inflammatory responses. Given the young age of onset, prenatal or perinatal exposure may be etiologically relevant. Multisystem inflammatory syndrome in children, a post-infectious hyper-inflammatory disorder associated with severe acute respiratory syndrome coronavirus 2, has features that overlap with those of KD. Available evidence indicates that vascular endothelial dysfunction is a critical step in the sequence of events leading to the development of cardiovascular lesions in KD. Oxidative stress and the dysregulation of the nitric oxide (NO) system contribute to the pathogenesis of inflammatory responses related to this disease. This review provides current evidence and concepts highlighting the adverse effects of oxidative injury and NO system derangements on the initiation and progression of KD and potential therapeutic strategies for cardiovascular pathologies in affected children.

Evaluation of the association of birth order and group childcare attendance with Kawasaki disease using data from a nationwide longitudinal survey

Background

Kawasaki disease (KD) is a form of pediatric systemic vasculitis. Although the etiology remains unclear, infections have been identified as possible triggers. Children with a later birth order and those who attend childcare are at a higher risk of infections due to exposure to pathogens from their older siblings and other childcare attendees. However, longitudinal studies exploring these associations are limited. Thus, we aimed to elucidate the relationship between birth order, group childcare attendance, and KD, using a nationwide longitudinal survey in Japan.

Methods

In total, 36,885 children born in Japan in 2010 were included. The survey used questionnaires to identify hospitalized cases of KD. We evaluated the relationship between birth order classification, group childcare attendance, and KD prevalence every year, from 6 to 66 months of age. For each outcome, odds ratios (ORs), and 95% confidence intervals (CIs) were estimated after adjusting for child factors, parental factors, and region of residence.

Results

Children with higher birth orders were more likely to be hospitalized with KD at 6-18 months of age (second child OR: 1.77, 95% CI: 1.25-2.51; third child OR: 1.70, 95% CI: 1.08-2.65). This trend was stronger for children who did not attend group childcare (second child OR: 2.51, 95% CI: 1.57-4.01; third child OR: 2.41, 95% CI: 1.30-4.43). An increased risk of KD hospitalization owing to the birth order was not observed in any age group for children in the childcare group.

Conclusions

Children with higher birth orders were at high risk for hospitalization due to KD at 6-18 months of age. The effect of birth order was more prominent among the children who did not attend group childcare.

Neonatal sepsis and Kawasaki disease

The purpose of this study is to clarify the relationship between neonatal sepsis and future development of Kawasaki disease (KD). We analyzed data from the National Hospital Organization Neonatal Intensive Care Unit (NHO-NICU) registry study in Japan. Participants in this study were children with a history of hospitalization in the NICU at the participating institutions from 2010 to 2014. A questionnaire was administered at age 3 years to obtain information about the patient's history of KD. There were 8275 infants who were eligible for this study. At 3 years of age, parents of 2161 children responded to the follow-up survey (follow-up rate, 26.1%). Multivariate logistic regression analysis adjusted for preterm birth, sex, use of antibiotics in the NICU, parity, and maternal smoking showed that children with neonatal sepsis were more likely to have a history of KD at 3 years of age (adjusted odds ratio [aOR]: 11.67, 95% confidence interval [CI]: 2.84-47.96).

CONCLUSIONS

Among infants admitted to the NICU, neonatal sepsis might be associated with development of KD later in life. Further large studies are needed to elucidate the relationship between neonatal infections and KD development.

WHAT IS KNOWN

• Preterm birth is known to be a risk factor for Kawasaki disease. •It is not yet known which factors related to preterm birth increase the risk of developing Kawasaki disease.

WHAT IS NEW

•Neonatal sepsis is associated with an increased risk of subsequent development of Kawasaki disease. •Antibiotic use in the neonatal intensive care unit may also be an independent risk factor for subsequent development of Kawasaki disease.

Association of Familial History of Diabetes, Hypertension, Dyslipidemia, Stroke, or Myocardial Infarction With Risk of Kawasaki Disease

Background

There are few studies on the association with Kawasaki disease in children and the family’s history of cardiovascular disease (CVD). The aim of this study was to identify the association of increased risks for Kawasaki disease in children with a family history of CVD.

Methods and Results

Clinical data of children born in 2008 and 2009 (n=917 707) were obtained from the National Health Insurance Service and the National Health Screening Program for Infants and Children for this study. The cohort consisted of 495 215 participants (53.8%) who completed the family history questionnaire for children 54 to 60 months old. Family history of CVD included 5 medical conditions: hypertension, dyslipidemia, myocardial infarction, stroke, and diabetes. Kawasaki disease was defined using the disease code, intravenous immunoglobulin prescription, and use of antipyretics for more than 25 days. Severe Kawasaki disease was defined as diagnosis of accompanied cardiac/coronary artery complications or intravenous immunoglobulin use ≥2 times. The incidence rate of Kawasaki disease was 124/100 000 person‐years (95% CI, 117.5–131.5) for children <2 years old, 95/100 000 person‐years (95% CI, 90.5–100.4) in children 2 to 5 years old, and 14/100 000 person‐years (95% CI, 12.6–15.6) in children >5 years old. After propensity‐score matching, 829 participants with a family history of CVD were diagnosed as having Kawasaki disease (0.68% [95% CI, 0.63–0.72]), and 690 patients with Kawasaki disease (0.56% [95% CI, 0.52–0.61]) had no family history of CVD. The family history of CVD was associated with increased risk for Kawasaki disease (risk ratio, 1.20 [95% CI, 1.08–1.32]) but not for severe Kawasaki disease (risk ratio, 1.23 [95% CI, 0.92–1.65]).

Conclusions

In this nationwide propensity‐score matched study, those with a family history of CVD had a significantly greater risk of Kawasaki disease compared with those who had no family history of CVD.