Creatinine-Cystatin C Ratio as Marker for Mortality Prediction in AKI

Patients in the intensive care unit (ICU) who develop acute kidney injury (AKI) are at increased risk of mortality. It is challenging to stratify mortality risk in this patient population. In critically ill patients, serum creatinine levels are confounded by muscle wasting; cystatin C is expected to be less modulated by muscle mass. Researchers conducted retrospective analyses to examine the association between creatinine-cystatin C ratio and mortality in patients requiring continuous renal replacement therapy (CRRT) in the ICU. Results were reported during a poster session at Kidney Week 2019.

The analyses included 443 patients in the ICU at a single center in South Korea who underwent CCRT between August 2009 and October 2016. The primary outcome of interest was 90-day mortality following initiation of CRRT.

Mean age of the cohort was 64 years and 57.3% were male. Sepsis was the most common cause of AKI. The median of the creatinine-cystatin C ratio was 0.83 (range, 0.13-6.20). Patients were stratified into four groups based on the creatinine-cystatin C ratio at the time of CRRT initiation. The 90-day mortality rates for each quartile (q) were 76.6% for q1; 73.9% for q 2, 61.3% for q3, and 51.8% for q4.

In multiple Cox proportional hazard models, the creatinine-cystatin C ratio was an independent predictor of 90-day mortality; the association remained after adjusting for confounding factors (hazard ratio, 0.97; 95% confidence interval, 0.95-0.99; P<0.01). Compared with APACHE-II or Sofa scores alone, consideration of creatinine-cystatin C ratio significantly improved prediction of mortality.

“Creatinine-cystatin C ratio is associated with mortality in ICU patients undergoing CRRT, and may be a practical marker in predicting survival among ICU patients with AKI,” the researchers said.

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Source: Jung C-Y, Ko B, Jo W, Yoo T-H, Park, JT. Creatinine-cystatin C ratio is associated with mortality in ICU patients undergoing continuous renal replacement therapy. Abstract of a poster presented at the American Society of Nephrology Kidney Week 2019 (Abstract TH-PO116), November 7, 2019, Washington, DC.