Adding cystatin C to serum creatinine testing better-identified patients at risk for end-stage kidney disease and all-cause death, new study findings indicate.

“Our results suggest that a triple-marker approach using both albumin-to-creatinine (ACR) and cystatin C to confirm CKD more accurately discriminates prognosis for death and progression to end-stage renal disease than creatinine and ACR alone,” researcher Carmen A. Peralta, MD, and colleagues wrote in the April 20 issue of the Journal of the American Medical Association.

The study was published online first to coincide with its presentation at the 2011 World Congress of Nephrology in Vancouver, British Columbia.

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The researchers measured rates of all-cause mortality and incident end-stage renal disease among 26,643 U.S. adults who participated in the Reasons for Geographic and Racial Differences in Stroke (REGARDS) study from January 2003 to June 2010.

Participants were categorized into eight groups based on estimated glomular filtration rates (GFR) as defined by creatinine and certain levels of cystatin C and ACR. Median follow up data at 4.6 years indicated that 1,940 patients died and 177 developed incident end-stage renal disease

Among the 2,904 participants whom had CKD based on creatinine: 24% had CKD confirmed with creatinine alone, 5% with creatinine and ACR, 40% with creatinine and cystatin C and 30% with all three biomarkers.

Furthermore, among patients that did not have CKD defined by creatinine alone, another 16% were reclassified using either ACR, cystatin C or both, data indicated, and hazard ratios for death increased when multiple biomarkers were detected (HR= 3.3 for participants with creatinine and ACR; HR=3.2 for participants with creatinine and cystatin C; and HR=5.6 for patients will all three biomarkers).

Similarly, patients who had CKD defined by all three biomarkers had a higher incidence of end-stage renal disease than those who’s CKD was detected by creatinine alone (34.1 per 100,000 person years vs. 0.33 per 1,000 person years).

The researchers also determined that the group at second highest risk for end-stage renal disease were the patients whose CKD was missed by creatinine, but was detected with cystatin C and ACR.

“The use of a triple-marker renal panel that improves prognostic ability could both reduce unwarranted referrals and unnecessary work-ups for low-risk individuals and would prioritize specialty care and interventions to individuals at highest risk,” the researchers wrote.