Dialysis and Low Creatinine a Bad Combo in AKI

In-hospital death risk is increased, a new study found.
In-hospital death risk is increased, a new study found.

Starting dialysis in patients with acute kidney injury (AKI) may increase their death risk if they have low creatinine concentrations, new findings suggest.

Dialysis can benefit patients with AKI, such as by increasing control of volume status and possibly allowing for better nutritional supplementation. Early initiation of the treatment, however, can lead to hypotension and delayed recovery of renal function, according to a research team led by F. Perry Wilson, MD, of the Renal, Electrolyte and Hypertension Division at the University of Pennsylvania School of Medicine in Philadelphia. The decision to start dialysis in patients with AKI often is subjective, based on multiple patient factors, the investigators noted.

Dr. Wilson and his colleagues evaluated adults who had been admitted to 1 of 3 acute care hospitals within the University of Pennsylvania Health System from January 2004 through August 2010, and who developed severe AKI during their stay: With baseline creatinine defined as the lowest serum creatinine concentration within 48 hours of hospital admission, all men had a baseline creatinine level of 1.4 mg/dL or lower and all women had a baseline creatinine level of 1.2 mg/dL or lower, with these levels doubling during hospitalization. A total of 545 patients in whom dialysis was initiated were matched to 545 patients in whom dialysis was not initiated on the same day of AKI.

As Dr. Wilson's group reported online in Clinical Journal of the American Society of Nephrology, the in-hospital mortality rate for patients in the highest tertile of serum creatinine level—higher than 4.2 mg/dL—was 47% for patients receiving dialysis compared with 57% for non-dialyzed patients. In the lowest tertile (serum creatinine lower than 2.8 mg/dL), in-hospital mortality was 78% for patients undergoing dialysis and 64% for those not receiving dialysis.

Compared with patients in the lowest tertile, those in the highest tertile were younger (mean age 58 years compared with 60 years), were more often male (76% in the highest tertile vs. 43% in the lowest tertile), and were more often black (23% in the highest tertile vs. 8% in the lowest tertile). More patients in the lowest tertile were in the intensive care unit—95% compared with 82% of those in the highest tertile.

The researchers calculated that the survival benefit yielded by dialysis increased by 20% for each increase of 1 mg/dL in serum creatinine concentration, even after adjustment for markers of disease severity. Dialysis was associated with more benefit than harm when initiated in patients with a creatinine concentration of 3.8 mg/dL or higher.

The finding that dialysis may do more harm than good in a certain subset of patients “is analogous to chemotherapy for cancer,” Dr. Wilson commented. “If you are strong enough to cope with the adverse effects, it's good for you, but if you're weak, it may kill you.”

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