Income disparities in prevalence and trends of chronic kidney disease among US adults, 2003–18

Aims: Chronic kidney disease (CKD) poses a significant health burden in the United States (US). Although earlier studies investigated income disparities in other chronic diseases, limited research has been carried out for CKD in recent years. We investigated income disparities in the prevalence and trends of CKD among US adults. Subjects and methods: This cross-sectional study analyzed National Health and Nutrition Examination Survey 2003–18 data. Survey periods were grouped as 2003–06, 2007–10, 2011–14, and 2015–18. Using glomerular filtration rate and urinary albumin-creatinine ratio from CKD-epidemiology equation, individuals ≥20-year-old were classified into stages of CKD. Income was derived from family income to poverty ratio and equally stratified as low-, middle-, and high-income. Results: In all periods, a reduction in CKD prevalence was observed as income-level increased. In 2003–06, the prevalence (95% confidence interval [CI]) of CKD was 17.8% (15.6%–20.3%), 14.7% (13.1%–16.4%), and 11.5% (10.3%–12.9%) among low-, middle-, and high-income people, respectively. It remained similar in 2007–10 and 2011–14. In 2015–18, this prevalence (95% CI) was 17.9% (16.5%–19.5%), 15.9% (14.6%–17.2%), and 10.2% (8.8%–11.8%) among low-, middle, and high-income people, respectively. Similar differences were detected across most age, gender, and race/ethnicity categories. Income differences were also observed in prevalence of CKD risk factors, including diabetes, obesity, metabolic syndrome, and smoking. Conclusion: While there was no increase in overall CKD prevalence, there could be an association between CKD and income, and low- or middle-income people had higher prevalence of CKD than high-income people. Lifestyle intervention and chronic disease-related health service provision need to consider the income disparity in CKD burden to improve the health and wellbeing of the US population.