Overall, fewer than one-quarter (24%) of North American pediatric CKD patients had proteinuria in the normal range; 62% had significant proteinuria and 14% had proteinuria in the nephrotic range.
Non-white patients had higher levels of proteinuria than white pediatric CKD patients (18.8% vs. 12.3% in the nephrotic range, respectively); similarly, patients with glomerular CKD diagnoses had higher levels than those without these diagnoses (31.9% vs. 9.5% in the nephrotic range, respectively)
The proportion with proteinuria also significantly increased with CKD stage, with significant or nephrotic-range proteinuria in 61.9%, 76.9% and 88.7% of those in CKD stage 1 or 2, stage 3 or stage 4, respectively.
Chart Explanation: Overall, fewer than one-quarter (24%) of pediatric CKD patients had proteinuria in the normal range; 62% had significant proteinuria and 14% had proteinuria in the nephrotic range. The distribution did not differ by gender (note that ~60-62% of pediatric CKD patients were male, regardless of proteinuria category; this differs from adult CKD patients, in whom females are the majority). Non-white patients and patients with glomerular CKD diagnoses were more likely to have significant or nephrotic-range proteinuria than their counterparts who were white and with another CKD diagnosis, respectively. The proportion with proteinuria also significantly increased with CKD stage, as defined by measured iohexol GFR.
The Chronic Kidney Disease in Children (CKiD) study is a prospective observational study of an estimated 500 children (1-16 years old) at 48 North American centers with varying degrees of CKD severity, which was designed to measure consequences in pediatric CKD patients. As with all cohort studies, recruitment bias and lack of representativeness may influence estimates.
Although data on CKD progression is not yet available from the CKiD study, proteinuria represents a risk factor for progression among those with CKD. As study follow-up continues, more data on CKD progression in these patients will be available and progression rates will replace baseline proteinuria as the measure of interest. Mortality as another possible health consequence will be tracked, but rates are expected to be too low to report among children. Another possible pediatric-specific consequence that may be available with further study follow-up is growth rate.
Analyses for this measure were restricted to the 419 children enrolled in CKiD with measured iohexol GFR and proteinuria (urine protein/creatinine or Up/c ratio, measured in g/g, thus presented without units) as well as known gender, age, CKD diagnosis and current medication use. Complete methods can be found in Wong et al. (2009)."
|Description of Measure||Prevalence of proteinuria among children with CKD|
|Data Source||CKiD prospective observational cohort study|
|Type of Data Source||Private|
|Data Set||CKiD summarized data|
|Health Care System Data||No|
|Regional or National?||National|
|Demographic Group||Children (1-16 years old) with mild to moderate CKD (Schwartz-estimated GFR of 30-90 ml/min/1.73 m²) who are treated throughout 48 pediatric nephrology centers in North America (46 U.S., 2 Canadian centers)|
|Numerator||Enrolled children with abnormal protein/creatinine (Up/c) ratio and with measured iohexol GFR as well as known gender, age, CKD diagnosis and current medication use|
|Denominator||Enrolled children with measured iohexol GFR and proteinuria (urine protein/creatinine or Up/c ratio) as well as known gender, age, CKD diagnosis and current medication use|
|Definition of CKD||Schwartz-estimated GFR of 30-90 ml/min/1.73 m² (for entry into study)|
|Glomerular filtration rate||Measured, by iohexol|
|Proteinuria||Normal, Up/c<0.2; significant, Up/c 0.2-2; and nephrotic, Up/c>2|
|Primary Data Source Indicator||Up/c|
|Primary Indicator Method of Measurement||Measured at central lab (University of Rochester) from 1st-morning urine samples|
|Secondary (1) Variable||GFR|
|Secondary (1) Indicator Method of Measurement||Measured by plasma iohexol disappearance curves (iGFR)|
|Frequency of Measurement (Primary)||At all scheduled visits; only baseline presented|
|U.S. Region Covered by Primary Variable||All|
|Period Currently Available||2004–2008|
|Pending Data||None for baseline; further visits scheduled|
|Additional Data Items of Interest||Stage of CKD, stratification variables of interest (age, gender, race/ethnicity )|
|Limitations of Indicator||Some samples may not be 1st morning; not all patients had iGFR measured|
|Analytical Considerations||Data summarized by CKiD investigators (see Wong et al.); as with all cohort studies, selection bias and possible confounding|
References and Sources:
Wong CS, Pierce CB, Cole SR, et al. CKiD Investigators. Association of proteinuria with race, cause of chronic kidney disease, and glomerular filtration rate in the chronic kidney disease in children study. Clin J Am Soc Nephrol. 2009;4(4):812-9.