April 12, 2011

Triple Marker Spots Kidney Failure

(Ivanhoe Newswire) -- Combining a chronic kidney disease marker with a biomarker was associated with improved prediction of end-stage kidney disease and all-cause death, according to new research.

Chronic kidney disease (CKD) is currently defined as certain levels of creatinine-based estimated glomerular filtration rate (GFR) or urine albumin-to-creatinine ratio (ACR), the kidney disease marker. Serum cystatin C, an alternative biomarker of kidney function, is not routinely used in clinical practice, according to background information in the article.

Carmen A. Peralta, M.D., M.A.S., of the San Francisco VA Medical Center, and colleagues conducted a study to evaluate whether combining creatinine, cystatin C, and urine ACR would improve identification of risks associated with CKD compared with the typical creatinine test alone.

Overall, 2,904 participants (11 percent) were classified as having CKD based on creatinine. Among them, 701 participants (24 percent) had CKD defined by creatinine alone, and 148 participants (5 percent) had CKD defined by creatinine and ACR, whereas CKD was defined by creatinine and cystatin C for 1,172 participants (40 percent) and by all biomarkers for 883 participants (30 percent). Among 23,739 participants with no CKD defined by creatinine, 3,863 (16 percent) had CKD detected by ACR, cystatin C, or both.

The researchers found that by adding cystatin C to creatinine and albuminuria for risk prediction could more accurately reclassify patients and distinguish important prognostic differences, namely a three-fold risk of death and four-fold risk of end-stage renal disease. Cystatin C and albuminuria were both strongly and independently associated with all-cause death among persons with or without CKD defined by creatinine-based estimated GFR. "The risk of future end-stage renal disease was concentrated within the subset of participants who had CKD defined by all 3 markers. The second highest risk group for end-stage renal disease was missed by creatinine but was detected by cystatin C and ACR," Peralta and colleagues were quoted as saying.

The authors note that several groups are currently advocating new international guidelines that more accurately reflect prognosis of CKD and have proposed adding ACR to staging of CKD.

"Our findings illustrate the potential implications of universal screening for CKD using a triple-marker approach," the researchers write. "Future studies are needed using the triple-marker approach to evaluate clinical strategies that may reduce these risks."

SOURCE: JAMA, published online April 11, 2011