The Congenital Heart Disease in Children: Kidney-Associated Conditions with Epidemiologic Endpoints (CHICKADEE) study: Study design and protocol.

Congenital heart disease affects approximately 1% of live births and represents the most common structural birth defect.

• There are now more than 2 million children and adults in the United States with CHD.
• The CHD population continues to grow due to improvements in medical and surgical management.
• The paper notes this as a 'vulnerable and growing population.'
• This statistic is cited as background context for the study's importance.

Children who undergo cardiac surgery for CHD face elevated risks of hypertension, chronic kidney disease, kidney failure, and premature mortality.

• These complications are described as 'more prevalent in those with single ventricle physiology.'
• Risks 'increase as they get older.'
• The paper characterizes these complications as 'under-recognized because they are understudied in pediatric populations.'
• The paper describes this as 'a critical missed opportunity for evaluation and early intervention.'

Emerging evidence suggests that the excess burden of CKD observed in adults with CHD originates in childhood.

• Despite this emerging evidence, CKD complications in CHD remain understudied in pediatric populations.
• Children with CHD represent a population 'largely excluded from existing pediatric nephrology cohorts.'
• This gap is identified as a primary motivation for the CHICKADEE study design.

The CHICKADEE study is designed to enroll 300 children aged 4 to 16 years across three clinical sites.

• Enrollment targets children 4 to 12 years after their initial CHD surgery.
• The cohort will be stratified by CHD severity.
• The study features enrichment for hypoplastic left heart syndrome and other single-ventricle defects.
• The study is described as 'the first comprehensive and collaborative longitudinal assessment of kidney outcomes in children with CHD.'

The study's primary outcomes include prevalent and incident hypertension, chronic kidney disease, and kidney failure.

• The study will use ambulatory blood pressure monitoring as part of hypertension assessment.
• Comprehensive phenotyping of kidney health will be conducted through standardized clinical assessments.
• Echocardiographic characterization will be included in the assessment protocol.
• Novel biomarker discovery will use both targeted and untargeted proteomic approaches.

A biorepository will be established as part of the CHICKADEE study to facilitate future ancillary studies.

• The biorepository is intended to support future research beyond the primary study endpoints.
• Both targeted and untargeted proteomic approaches will be used for biomarker discovery.
• The study aims to 'inform risk stratification, enable early detection strategies, and guide development of targeted interventions to preserve long-term kidney health.'