Children and adolescents who have chronic kidney disease (CKD) and are from lower-income households are at higher risk of impaired growth than are youths from middle- and high-income homes, a recent study indicates.

The study included 572 U.S. and Canadian children and adolescents participating in the multicenter, prospective Chronic Kidney Disease in Children Study, which is primarily funded by the National Institutes of Health’s National Institute of Diabetes and Digestive and Kidney Diseases (NIH/NIDDK). Patients were aged 1 year to 16 years and all had mild to moderate CKD.At baseline, median glomerular filtration rates (GFRs) were similar across low-income (annual household income of less than $30,000), middle-income ($30,000 to less than $75,000), and high-income ($75,000 or higher) categories, at 43-45 mL/min/1.73m2.

Low and middle household incomes were associated with minority race (39% and 20%, respectively, vs. 7% for high income), lower maternal education (28% and 5% vs. 1%), abnormal birth history (34% and 32% vs. 21%), and the presence of at least one clinical comorbid condition (66% and 64% vs. 55%).

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After adjusting for baseline differences, GFRs were seen to decline an average of 2.3% per year in the low-income group, 2.7% per year in the middle-income group, and 1.9% per year in the high-income group. According to an NIH/NIDDK statement accompanying the release of the findings, the statistical nonsignificance of the differences in GFR reductions between groups surprised researchers Marva Moxey-Mims, MD—a pediatric kidney specialist at the NIH/NIDDK—and colleagues, who expected more rapid declines in kidney function among the participants with lower socioeconomic status.

Dr. Moxey-Mims and co-investigators further reported in American Journal of Kidney Diseases (2013;62:1087-1094) that the children with lower socioeconomic status were likely to be substantially shorter than their higher-income counterparts and shorter than children of the same age from all income levels without CKD. Overall, height deficits at baseline were similar between the three study groups, but diminished over time only for patients from high-income families.

“Since these lower [socioeconomic status] children received higher proportions of prescriptions for growth hormone, it’s possible that these families are not filling all these prescriptions or are filling them but not sticking to their treatment regimen as closely as higher-income families are,” Dr. Moxey-Mims said in the statement. “There also could be other issues like nutrition or household finances contributing to this difference.”

Although blood pressure tended to improve in all groups, faster improvement was noted in the higher-income group: Youths from lower-income households took a mean 4.5 years to bring their blood pressure levels to within the normal range, compared with an average of two years for the higher-income patients.