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Regardless of Age, Measures of Kidney Function Remain Predictors of Kidney Disease and Death

EMBARGOED FOR EARLY RELEASE: 2:00 P.M. (CT) TUESDAY, OCTOBER 30, 2012
Media Advisory: To contact corresponding author Josef Coresh, M.D., Ph.D., call Tim Parsons at 410-955-7619 or email tmparson@jhsph.edu. To contact editorial author Ian H. de Boer, M.D., M.S., call Clare LaFond at 206-685-1323 or email clareh@uw.edu.


CHICAGO – In a large, collaborative study that included more than 2 million individuals from around the world, two measures of poor kidney function, low estimated glomerular filtration rate and high albuminuria, were associated with risk of death and end-stage renal disease regardless of the age of the individuals, according to a study appearing in JAMA. The study is being release early online to coincide with its presentation at the American Society of Nephrology’s Kidney Week meeting.

“Chronic kidney disease (CKD) is defined by reduced glomerular filtration rate [GFR less than 60 mL/min/1.73 m2] or kidney damage (usually detected by high albuminuria; e.g., 30 mg or greater of albumin per 1 gram of creatinine). Chronic kidney disease affects 10 percent to 15 percent of adults in the United States, Europe, and Asia, and the prevalence increases dramatically with age (from 4 percent at age 20-39 to 47 percent at age ≥70 years in the United States). Recently, it has been suggested that the definition and staging of CKD and corresponding clinical risk should be determined by the combination of estimated GFR (eGFR) and albuminuria levels,” according to background information in the article. “However, controversy exists about whether age modifies their independent and combined association with clinical risk, partly because of different analytic approaches. The resulting uncertainty about the comprehensive effect of age on the CKD-risk relationship hampers optimal clinical practice and public health initiatives for this large patient group.”

Stein I. Hallan, M.D., Ph.D., of the Norwegian University of Science and Technology, Trondheim, Norway, and colleagues conducted a study to evaluate the possible effect of age on the association of eGFR and albuminuria with risk of death and end-stage renal disease (ESRD), examining both relative and absolute risks. The study included 2,051,244 participants from 33 general population or high-risk (of vascular disease) cohorts and 13 CKD groups from Asia, Australasia, Europe, and North/South America, conducted from 1972-2011, with an average follow-up time of 5.8 years.

After meta-analysis of the data, the researchers found that mortality (112,325 deaths) and ESRD (8,411 events) risks were higher at lower eGFR and higher albuminuria in every age category. “We found that mortality risk associations were weaker on the relative scale but stronger on the absolute scale at older ages in general population and high-risk cohorts. In cohorts specifically selected for CKD, age did not modify the mortality associations. For ESRD risk, age did not significantly influence relative and absolute risk gradients. Thus, eGFR and albuminuria were strongly associated with both mortality and ESRD in a wide range of studies across the full age range. Importantly, the results were largely consistent across diverse cohorts in terms of demographic and clinical characteristics.”

The authors add that their findings have several important implications. “First, our study shows that the kidney measures used for defining and staging CKD are strong predictors of clinical risk across the full age range, including age 75 years or older in many cohorts. This contradicts concerns raised by some that current CKD guidelines should be used with caution in older individuals and that low eGFR reflects only natural aging. … Second, our data support the recommendations from several investigators that CKD measures should be added to mortality risk equations. … Third, the strong increase in mortality rate along with kidney measures at older ages suggests that older adults should not be left out from management strategies of CKD.”

“Although some variation in management of CKD should be considered by age based on cost and benefits, with respect to risk of mortality and ESRD, our data support a common definition and staging of CKD based on eGFR and albuminuria for all age groups.”
(doi:10.1001/jama. 2012.16817;. Available pre-embargo to the media at http://media.jamanetwork.com)

Editor’s Note: Please see the article for additional information, including other authors, author contributions and affiliations, financial disclosures, funding and support, etc.

Chronic Kidney Disease–A Challenge For All Ages

Ian H. de Boer, M.D., M.S., of the University of Washington, Seattle, comments on the findings of this study in an accompanying editorial.

“For physicians to help improve the lives of patients with CKD, identifying the presence of CKD and its associated risks is an important first step. In this respect, [the results of this study] makes it clear that CKD is a challenge for all ages. To move forward, CKD identification must be coupled to new treatment strategies tailored to patients with CKD, including older patients with CKD.”
(doi:10.1001/jama. 2012.30761;. Available pre-embargo to the media at http://media.jamanetwork.com)

Editor’s Note: The author has completed and submitted the ICMJE Form for Disclosure of Potential Conflicts of Interest. Dr. de Boer receives research funding from the National Institutes of Health and Abbott Laboratories.

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