Background
Among adults, lower socioeconomic status (SES) is a risk factor for chronic kidney disease (CKD), progression to end stage renal disease, and poor health outcomes, but the effect among young people with CKD is not well known.
Study Design
Prospective cohort study.
Settings & Participants
572 children and adolescents aged 1 to 16 years with mild to moderate CKD residing in the United States and Canada who were enrolled in the Chronic Kidney Disease in Children (CKiD) Study, a multicenter prospective cohort.
Predictor
Self-reported annual household income category as a proxy measure for SES: ≥$75,000 (high income), $30,000 to <$75,000 (middle income) and<$30,000 (low income).
Outcomes & Measurements
Clinical characteristics and CKD severity at baseline (GFR; comorbidities related to disease severity and management) and longitudinally (GFR decline; changes in blood pressure z scores and height z scores per year).
Results
At baseline, low and middle household incomes, compared to high income, were associated with minority race (39% and 20% vs. 7%), lower maternal education (28% and 5% vs. 1%), abnormal birth history (34% and 32% vs. 21%), and having at least one clinical comorbidity (66% and 64% vs. 55%).Baseline median GFRs were similar across income categories(between 43 and 45 ml/min/1.73m2). After adjusting for baseline differences, the average GFR declines per year for the high, middle and low income categories were −1.9%, −2.7%, and −2.3%, respectively, and were not statistically significantly different between groups. Blood pressure control tended to improve in all groups (z score, between −0.10 and −0.04), but this was not associated with income. Height deficits diminished over time for subjects from high income families but not among subjects from low income families(z scores for height per year, 0.05 and −0.004, respectively; P = 0.03 for comparison of high and low income).
Limitations
Statistical power to detect associations by income level is limited; income is an imperfect measure for SES; CKiD participants are not representative of children and adolescents with CKD who are uninsured or not receiving care.
Conclusions
GFR decline and blood pressure control were comparable across income groups. Children and adolescents with CKD from lower income households are at higher risk of impaired growth.
