Association of Income Level With Kidney Disease Severity and Progression Among Children and Adolescents With CKD: A Report From the Chronic Kidney Disease in Children (CKiD) Study

Abstract

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.

Clinical Implications of the Solitary Functioning Kidney

“…This evaluation should focus on identified risk factors, such as ipsilateral CAKUT, small renal size, low birth weight, prematurity, and history of urinary tract infection. In addition, the Chronic Kidney Disease in Children cohort study has identified clinical (anemia, hyperphospatemia, and short stature) (50) and socioeconomic (lower income and lower maternal education) (51) risk factors that are associated with the development of CKD in children, including solitary functioning kidney patients. Risk assessment also requires imaging techniques, such as renal ultrasound, in all patients and on indication, renal scintigraphy and/or a micturating cystourethrogram (for additional CAKUT including VUR) together with repeated follow-up of renal length.…”

Medication Adherence and Growth in Children with CKD

“…There is a perception that shorter children may be more motivated to take rhGH because of peer concerns; however, this was not supported by our data, because there was no difference in nonadherence among those with height z scores#3rd percentile versus .3rd percentile. More detailed analysis of the possible association between socioeconomic status, medication nonadherence, and growth is warranted, especially in light of the recent data regarding linear growth in children of low socioeconomic status (30,31). Analysis of parental and patient self-perceived barriers to adherence may provide additional clues and help to develop an effective intervention.…”

Renal and Cardiovascular Morbidities Associated with APOL1 Status among African-American and Non-African-American Children with Focal Segmental Glomerulosclerosis

“…Since lower socioeconomic status (SES) was associated with AA race in this North American cohort, and low SES is associated with disease progression (20), SES is a potential confounder as the exposure groups largely differ by race. To adjust for confounding due to SES, we used inverse probability of exposure weights (IPWs) (21, 22).…”