Study Design

CKiD is a prospective, observational cohort of children with chronic kidney disease. The exposures and outcome of interest are measured at a participant’s first study visit, and then continually collected at annual follow-up visits, allowing investigators to understand how CKD and the health of this population change over time.

There are many outcomes of interest measured at CKiD yearly follow-up visits. A few of them include measures of kidney function such as GFR and urine protein to creatinine ratio, neurocognitive function, markers of risk factors for cardiovascular disease, growth, and other co-morbid conditions. CKiD leverages the power of the cohort study design through these regularly scheduled visits where markers of disease progression can be measured in a standardized setting. CKiD also collects data on important clinical events that are particularly meaningful to this population, specifically the onset of end-stage kidney disease (ESKD) and death.

CKiD has recently started following participants after transplant and initiation of dialysis (kidney replacement therapy (KRT)). Collecting data on participants in this phase will allow investigators to understand the determinants of long-term positive outcomes post-KRT.

For a full description and schedule of CKiD study visits, please see the schematics below.

Study Population

The CKiD Study enrolls children and adolescents with mild-to-moderate CKD of both glomerular and non-glomerular disease etiology. CKiD has been enrolled in 3 waves: Cohort 1, Cohort 2, and Cohort 3.

Cohort 1 enrolled approximately 600 racially and ethnically diverse children between the ages of 1 and 16 with GFRs between 30 and 90 ml/min|1.73m2. Cohort 2 enrolled approximately 300 children with slightly more mild CKD compared to those in Cohort 1, as the GFR requirement was was between 45 and 90 ml/min|1.73m2. Finally, Cohort 3, the most recent cohort, enrolled roughly 200 participants between the ages of 6 months and 16 years with a non-glomerular CKD diagnosis. Additionally, this cohort must have received their diagnosis within 5 years of being enrolled in order to allow investigators to study disease progression closer to its initiation.

Please see below for specific details on the inclusion and exclusion criteria of the CKiD Study.

Inclusion & Exclusion Criteria

General Inclusion Criteria

  • Age between 1 and 16 years (before 17th birthday) for Cohorts 1 and 2;age between 6 months and 16 years (before 17th birthday) for Cohort 3
  • Estimated (based on SCr) Schwartz GFR between 30 and 90 ml/min|1.73m2 for Cohort 1 OR an estimated GFR between 45 and 90 ml/min|1.73m2 based on the updated Schwartz formula for Cohort 2
  • Willingness and ability to provide informed consent and assent
  • For Cohort 2, an equal distribution of children with glomerular and non-glomerular causes of disease were enrolled (i.e., 150 within each) and the study placed an upper limit of 60% for the percent of enrolled with non-glomerular disease.
  • For Cohort 3, 190 children with non-glomerular diagnosis and duration of kidney disease less than 5 years will be enrolled.

Patients with the non-glomerular diagnoses listed below that meet the initial criteria (i.e., duration of kidney disease less than 5 years, and age between 6 months and 16 years old) are eligible and do not have to meet additional criteria:

  • Branchio-oto-Renal Disease/Syndrome
  • Cystinosis
  • Medullary cystic disease/ juvenile nephronophthisis
  • Methylmalonic Acidemia
  • Oxalosis
  • Polycystic kidney disease (Autosomal recessive)

However, all other patients with non-glomerular diagnoses will require at least two of the following conditions. All conditions except for abnormal imaging/biopsy must have occurred after the initial 6 months of life and must not be secondary to a current or resolving episode of Acute Kidney Injury (AKI):

  • Significant proteinuria
    • Age < 2 years old: urine protein to creatinine ratio > 0.5
    • Age ≥ 2 years old: urine protein to creatinine ratio > 0.2
  • Hematuria (for at least 3 months)
  • Evidence of renal tubular disorders
  • Abnormalities detected by kidney biopsy or imaging
  • Abnormal kidney function
    • Age < 2 years old: serum creatinine > 0.4 mg/dL
    • Age ≥ 2 years old: eGFR < 90 ml/min|1.73m2 (eGFR=41.3 x height[meter]/creatinine[mg/dL])
  • Hypertension defined by one of the following:
    • Documented hypertension noted in the medical record by the physician
    • Current treatment of hypertension
    • Blood pressure > 95th percentile for age and gender on at least two occasions
  • Renal, other solid organ, bone marrow or stem cell transplantation
  • Dialysis treatment within the past three months
  • Cancer diagnosis or HIV diagnosis/treatment within last twelve months
  • Current pregnancy or pregnancy within past twelve months
  • Inability to complete major data collection procedures
  • Current enrollment in a randomized clinical trial in which the specific treatment is unknown
  • Not fluent in English or Spanish
  • Plans to move out of area of any participating CKiD site (Families can be transferred to another CKiD site if they move)
  • History of structural heart disease
  • Genetic syndromes involving the central nervous system (e.g., Downs syndrome)
  • History of severe to profound mental retardation (i.e., IQ less than 40, significant impairment in adaptive function and/or inability to independently execute self-care skills)
  • For cohort 3, children who are expected to receive renal replacement therapy within 6 months of date of enrollment will not be recruited

Study Visit Schedule for Regular Follow-Up

Study Visit Schedule for Post-RRT Follow-Up

Click here to download a combined, PDF version of the Regular and Post-RRT CKiD Follow-Up Schedules.