Socioeconomic Status and Markers of Subclinical Cardiovascular Disease in Children with CKD

Adult and pediatric patients with chronic kidney disease (CKD) are at high risk for cardiovascular disease-related morbidity and mortality. Results of previous studies indicate that African American adults with CKD are at higher risk of cardiovascular disease-related morbidity and mortality than White adults with CKD. In children with CKD, lower socioeconomic status may worsen patient and family stress, anxiety, and depression, making it difficult to adhere to medical regimens, In addition, socioeconomic factors such as low household income have been associated with other adverse health indicators such as poorer growth in children with CKD. African Americans face chronic stress associated with systemic racism, affecting health through changes in psychological, physiological, and behavioral pathways.

There are few data available on the association between race and social determinants of subclinical cardiovascular health among children with CKD. Kristen Sgambat, PhD, and colleagues conducted a study to examine differences in socioeconomic factors and subclinical cardiovascular disease markers by race among participants in the CKiD (Chronic Kidney Disease in Children) study and whether differences in cardiovascular disease markers persist following adjustment for socioeconomic factors. The researchers also sought to test the hypothesis that racial differences in CKD may vary according to CKD diagnosis due to risk factors exclusively related to glomerular disease, including proteinuria, dyslipidemia, and exposure to immunosuppressants. Study results were reported in the American Journal of Kidney Diseases [2021;78(1):66-74].

The outcomes of interest were ambulatory hypertension, left ventricular mass index (LVMI), triglycerides, and high-density lipoprotein (HDL) cholesterol. Eligible participants were children with mild-to-moderate CKD with at least one cardiovascular parameter measurement (ambulatory blood pressure, LVMI, or lipid profile).

The analysis was stratified by cause of CKD. Socioeconomic status (health insurance, household income, maternal education, food insecurity, abnormal birth history) was adjusted using inverse probability weighting. The association between race and cardiovascular markers was assessed using linear and logistic regression.

Of the 1032 participants in the CKiD study, 174 were excluded for self-report of a race other than White or African American, and another 230 were excluded for missing outcomes of interest, or not meeting age or estimated glomerular filtration rate (eGFR) inclusion criteria. The final cohort for the present analysis included 3103 visits from 628 children. At baseline, median age was 10.7 years and median eGFR was 43.2 mL/min/1.73 m². Of the 628 children, 20.8% were African American and 26.3% had glomerular CKD.

Regardless of the cause of CKD, African American children had shorter lengths of study follow-up than White children (median, 4.4 years vs 5.2 years for nonglomerular CKD and 2.6 vs 3.7 years for glomerular CKD). Among the 463 children with nonglomerular CKD, 383 were White and 80 were African American. Of the 165 children with glomerular CKD, 114 were White and 51 were African American.

The proportion of adverse socioeconomic characteristics was greater among African American children than among White children regardless of CKD cause. African American children were more likely to have public health insurance, food insecurity, and abnormal birth history, in addition to lower maternal education and household income. There were no differences between the two groups in household smoking. Among African Americans, maternal age <18 years was more prevalent in the glomerular cohort; there was no significant difference by race in the cohort with nonglomerular CKD.

Use of angiotensin-converting enzyme inhibitor/angiotensin II receptor blocker (ACEi/ARB) was higher among White children in the nonglomerular group than among African American children (45% vs 33%, respectively; P=.04). The same pattern was nominally present in the group with glomerular CKD (85% vs 78%, respectively) but did not reach statistical significance. Regardless of the CKD cause, obesity was more prevalent among African American children.

Rates of immunosuppressive medication, nephrotic-range proteinuria, and higher urinary protein-to-creatinine ratio were higher among participants with glomerular CKD; the nonglomerular group was more likely to be diagnosed with CKD at birth.

In the nonglomerular CKD cohort, prior to and after adjusting for socioeconomic status, age, and sex, there was a significant association between African American race and a more favorable lipid profile (lower triglycerides and higher HDL cholesterol); the magnitude of the differences was attenuated in the adjusted models for triglycerides and HDL cholesterol. African American race was associated with significantly higher odds of ambulatory hypertension prior to and after adjusting for socioeconomic status, age, and sex; the magnitude of the difference was attenuated in the model adjusted for socioeconomic status, age, and sex, but the difference remained statistically significant. LVMI was significantly higher among African Americans than among White participants.

In the glomerular CKD group, there was a significant association between African American race and higher LVMI in both the unadjusted (20.6%) and adjusted (32.1%) models (P<.001). There were no statistically significant differences in ambulatory hypertension, triglycerides, or HDL cholesterol between African American and White participants in the unadjusted or adjusted models in the glomerular CKD group.

The researchers conducted an additional ad hoc model in a subset of 828 visits of 366 children who had both LVMI and ambulatory blood pressure monitoring performed at the first follow-up visit to determine if racial differences in LVMI persisted following additional adjustments for ambulatory hypertension.

In the nonglomerular CKD group, African American children had 12.1% (unadjusted; P=.001) higher LVMI than White children; in the subset with LVMI and ambulatory blood pressure monitoring, African American children had 13.1% higher LVMI than White children (unadjusted; P=.009). In the ad hoc analysis, there was a nominal association between African American race and higher LVMI following adjustment for socioeconomic status, age, sex, and ambulatory hypertension; the association was not statistically significant.

In the glomerular CKD group, LVMI was 20.6% higher in African American children compared with Whites (unadjusted; P<.001); in the subset, the percentage in African American children was 16.4% (unadjusted; P=.009). Following adjustments, the association between African American race and higher LVMI remained statistically significant (23.0%; P=.004).

In citing limitations to the findings, the researchers noted that the study design limited causal inference.

In conclusion, the authors said, “African American children are disproportionately affected by socioeconomic disadvantages compared with White children. The degree to which cardiovascular markers differ by race is influenced by etiology of CKD. African Americans with nonglomerular CKD have increased LVMI, more ambulatory hypertension, and more favorable lipid profile, but the magnitude of these differences appears slightly attenuated after adjustment for socioeconomic status. African American children with glomerular CKD have increased LVMI but exhibit similar lipid profiles and ambulatory hypertension compared with White children before and after adjustment for the socioeconomic status factors included in this analysis. Further research should use more sensitive measurements of subclinical cardiovascular dysfunction and focus on investigating elements of racism as determinants of cardiovascular health in children with CKD.”

Takeaway Points

1. Researchers reported results of an analysis to identify differences in socioeconomic factors and subclinical cardiovascular disease markers by race among participants in the Chronic Kidney Disease in Children study.
2. The analysis was stratified by CKD cause: glomerular CKD and nonglomerular CKD.
3. African American children were disproportionately affected by adverse socioeconomic factors compared with White children. The degree to which cardiovascular markers differ by race was influenced by disease etiology.