Dr Guofen Yan On the Mechanism Behind Racial Disparities in ESKD Incidence

High incidence of kidney failure in minority groups can be attributed to faster progression of kidney function decline in these populations, said Guofen Yan, PhD, associate professor of biostatistics in the department of public health sciences at the University of Virginia School of Medicine.

Transcript:

Why did you decide to research the mechanism behind higher incidence of end stage kidney disease (ESKD) among different racial/ethnic groups?

We observed that in the United States, Black and Hispanic populations are observed to have a higher incidence of kidney failure compared to the White population. Here incidence of kidney failure refers to the number of new cases of kidney failure per million population per year. For example, according to the most recent data reports in 2017, roughly the adjusted incidence of kidney failure was 3-fold higher for Blacks and 1.5-fold higher for Hispanics compared to Whites. At this time, the reason behind the high incidence of kidney failure in Hispanics and in Blacks has not been completely understood, because, the high incidence of kidney failure does not necessarily mean the faster progression. Because it could also be possible due to the low mortality prior to kidney failure, because a low mortality of a particular group can result in more people of this group staying alive to develop kidney failure. So, these are 2 different mechanisms. One is faster progressing, the other is due to low mortality.

It has not been teased out whether which one is a dominant reason or the population force to drive the high incidence of kidney failure that we have observed among the general population. The purpose of our study was to examine in particular which reason among these 2 is mainly responsible for the high incidence of kidney failure among Blacks and Hispanics.

How did you carry out your study and what were the main findings?

This was a large epidemiology population study, nationwide study, with data extracted from the US Veteran Health Care System. We examined 850,000 veterans with newly developed chronic kidney disease from 2002 to 2015, they were followed up to 14 years through 2016. This was a unique study in terms of scale, in terms of nationwide coverage, in terms of longer follow-up. We then examined the risk of kidney failure and the risk of death prior to kidney failure simultaneously to understand the reason behind the high incidence of kidney failure.

What we found is that 10 years after CKD onset, the cumulative incidence of kidney failure was 2 times higher for Hispanics and Blacks with CKD compared to Whites. This means that, indeed after CKD onset Blacks and Hispanics were 2 times more likely than Whites to approach kidney failure. Again, this does not necessarily mean they have a high risk of progression. So with this data, we next examined the risk of kidney failure and the risk of death without kidney failure simultaneously. We found that the risk of death before kidney failure was not much different across 3 risk groups, meaning the 3 groups had a similar mortality risk prior to kidney failure. However, in contrast, the risk of kidney failure was particularly high, was 2-fold higher for Blacks and Hispanics compared to Whites. This was really consistent across age groups. After taking into account the comorbidity and gender and medication and body mass index, the risk of kidney failure was substantially greater for Blacks and Hispanics compared to Whites. In contrast, they had a similar mortality risk before kidney failure and then we concluded that the higher incidence of kidney failure observed in the general population in Blacks and Hispanics was indeed due to higher kidney failure risk. We also found that this higher kidney failure risk was attributed to the faster decline in kidney function after CKD onset. So that's our conclusion, that the high incidence of kidney failure observed in the general population in these minority groups was indeed due to the faster kidney function decline for these groups, rather than because of the lower mortality rate prior to kidney failure.