BEST: Blood urea nitrogen level may be linked to high-dose loop diuretic-associated mortality

Testani JM. J Am Coll Cardiol. 2011;58:375-382.

Issue: August 2011

Patients with high blood urea nitrogen levels who were treated with high-dose loop diuretics had a mortality risk of nearly 60%, according to study results.

There were 2,456 patients from the Beta-Blocker Evaluation of Survival Trial (BEST) evaluated to determine the interaction between blood urea nitrogen level and mortality associated with use of at least 160 mg per day high-dose loop diuretics.

Use of such diuretics was linked to increased mortality (HR=1.56; 95% CI, 1.35-1.80). However, this association did not remain after controlling for baseline characteristics (HR=1.06; 95% CI, 0.89-1.25).

Among patients with blood urea nitrogen levels above the median of 21 mg/dL who were treated with high-dose loop diuretics, the unadjusted HR for risk of death was 1.59 (95% CI, 1.34-1.88), and the adjusted HR was 1.29 (95% CI, 1.07-1.60). For patients with blood urea nitrogen levels below the median, treatment with high-dose loop diuretics was not associated with increased mortality (HR=0.99; 95% CI, 0.75-1.34). After controlling for baseline characteristics, improved survival rates were observed in the high-dose loop diuretics group (HR=0.71; 95% CI, 0.49-0.96).

Researchers from the University of Pennsylvania aimed to investigate whether blood urea nitrogen — a surrogate for renal neurohormonal activation — could be an effective way to identify patients who may be likely to experience adverse outcomes associated with the use of high-dose loop diuretics.

Although loop diuretics are commonly used to control congestive symptoms in HF, they may cause neurohormonal activation and have been linked to lower survival rates.

“These data suggest a role for neurohormonal activation in loop diuretic-associated mortality,” the researchers wrote.

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