Mortality risk increases significantly in individuals who have albumin in their urine, even if they do not have marked reductions in kidney function, as measured by estimated glomerular filtration rate (eGFR), according to findings presented at the National Kidney Foundation 2016 Spring Clinical Meetings.
Linking albuminuria to increased mortality in individuals without significant reductions in eGFR suggests that there could be benefits to more widespread screening for albuminuria, given that urine testing is relatively inexpensive, the researchers said.
“Our study found that individuals with albuminuria had approximately twice the risk of mortality, at all levels of eGFR, compared to individuals without albuminuria,” said Jennifer Bragg-Gresham, PhD, research scientist at the University of Michigan. “Our results suggest that increased albuminuria testing, even among those with normal eGFR, could provide the impetus for preventive measures to lower mortality risk.”
The study was based on National Health and Nutrition Examination Survey (NHANES) data from 25,160 adults, excluding those with kidney failure. Researchers investigated the association of eGFR and albuminuria (urine albumin/creatinine ratio >30 mg/g) on mortality using survey weighted Cox models that were adjusted for age, sex, race, BMI, diabetes, hypertension, and medication usage.
Researchers found that individuals with albuminuria had double the risk of mortality at all levels of eGFR.
Previous studies have shown that albuminuria is a risk factor for cardiovascular disease. It is also associated with a more rapid progression of kidney disease and greater risk of kidney failure.
According to Bragg-Gresham, analysis of NHANES data indicates that approximately 8% of the U.S. population has albuminuria. However, current screening guidelines miss many of these individuals because it is recommended that annual urine testing be done only among specific patient populations such as those with diabetes, high blood pressure, age over 60, and those with a family history of kidney failure.
“The problem is that awareness of kidney disease is very low, especially in its early stages, where albuminuria is present without a decrease in eGFR,” said Dr. Bragg-Gresham.
After publishing their findings later this year, Bragg-Gresham and her team will focus on the cost-benefit of expanding urine albumin testing guidelines to a larger proportion of the population.
“Based on our estimates, over 15 million people in the United States have albuminuria without a decrease in eGFR,” she said. “If less than 5% of these individuals are aware they have early stage kidney disease, there are potentially more than 14.5 million individuals who could be identified and measures taken to slow the progression of their kidney disease and reduce their risk of all-cause mortality.”