Racial, Socioeconomic Disparities Continue in Prevalence of CKD Over Time

The prevalence of chronic kidney disease (CKD) in the United States, which has received new focus in recent years among payers, leveled off over a 28-year period, according to a new study released Thursday, but significant health disparities remain, especially among Mexican Americans.

CKD affects 15% of the US population and is linked to cardiovascular disease. In its worst form, end-stage renal disease requires dialysis or transplantation, both expensive options. In addition, CKD is a risk for more severe complications resulting from coronavirus disease 2019, which is also taking a more deadly toll on communities of people of color.

The study, published in JAMA Network Open, examined trends from 1988 to 1994 and then every 2 years from 1999 to 2016. The aim of the study was to investigate CKD by race/ethnicity and socioeconomic status.

The researchers used the National Health and Nutrition Examination Surveys (NHANES), which are nationally representative surveys. NHANES III was conducted from 1988 to 1994; beginning in 1999, NHANES collected data continuously and released it in 2-year data cycles. This study used data from NHANES III (1988-1994) through NHANES 2015-2016.

Participants were included if they were aged 20 years or older and had measurable serum creatine measurements.

Race/ethnicity and socioeconomic status were self-reported, and race/ethnicity was categorized into 4 groups: non-Hispanic white, non-Hispanic black, Mexican American, and other. Educational level was categorized into 3 categories: less than high school (low), high school or equivalent (medium), and more than high school (high).

Low income was categorized as having a poverty income ratio of less than 1.0; middle as 1.0-3.9; and high as 4.0 or more.

Prevalence of CKD was defined as an estimated glomerular filtration rate of 15 to 59 mL/min/1.73 m², and outcomes were stage 3 and stage 4 CKD.

A total of 54,554 participants were included; mean age was 46 [0.2] and 51.7% were female.

The age-, sex- and race/ethnicity-adjusted overall prevalence of stage 3 and 4 CKD increased from 3.9% in 1988-1994 to 5.2% in 2003-2004 (difference, 1.3%; 95% CI, 0.9%-1.7%; P < .001). In 2015-2016, it remained relatively stable at 5.1% (difference, −0.1%; 95% CI, −0.7% to 0.4%; P = .61).

By race/ethnicity, the trend in adjusted CKD prevalence differed significantly (P = .009). In non-Hispanic white and non-Hispanic black persons, CKD prevalence increased between 1988-1994 and 2003-2004 and remained stable afterwards.

But prevalence almost doubled among individuals of Mexican descent between 2003 and 2004 and then again from 2015 to 2016 (difference, 2.1%; 95% CI, 0.9%-3.3%; P = .001). During the other time periods, CKD prevalence was lower than in other racial/ethnic groups and remained stable between 1988-1994 and 2003-2004.

The authors said the observations seen in Mexican Americans is consistent with the recently observed worsening health status among Hispanic individuals; moreover, the results are unlikely to be due to racial/ethnic differences that are seen in disparities of diabetes and hypertension, since the differences persisted even after adjusting for those factors.

By education and income, the higher CKD prevalence stayed consistent among those with lower levels throughout the entire study period. In addition, there were higher rates of CKD prevalence among groups with lower socioeconomic attainment (eg, 5.8% vs 4.3% and 4.3% vs 3.1% in low vs high education and income, respectively, in 1988-1994). But prevalence trends matched those for the overall population.

"Although the aim of this study was not to elucidate causes, it is conceivable that consistent inequality in CKD prevalence could be in part owing to health-promoting interventions not targeting specific at-risk groups or not being specifically designed to be capable of eliminating or reducing disparities," the authors wrote.

Reference

Vart P, Powe NR, McCulloch CE, et al. National trends in the prevalence of chronic kidney disease among racial/ethnic

and socioeconomic status groups, 1988-2016. JAMA Netw Open. Published online July 16, 2020. doi:10.1001/jamanetworkopen.2020.7932