Representativeness of RELAX-AHF clinical trial population in acute heart failure

Circ Cardiovasc Qual Outcomes. 2014 Mar;7(2):259-68. doi: 10.1161/CIRCOUTCOMES.113.000418. Epub 2014 Mar 4.


Background: The Relaxin for the Treatment of Acute Heart Failure (RELAX-AHF) trial enrolled 1161 patients admitted to the hospital for acute heart failure (AHF) to evaluate the therapeutic efficacy of serelaxin, a recombinant form of human relaxin-2. We characterized how representative RELAX-AHF clinical trial enrollees were to those patients with AHF found in international registries.

Methods and results: We examined 196 770 AHF admissions from the Acute Decompensated Heart Failure National Registry-United States and Acute Decompensated Heart Failure National Registry-International registries. Patients were considered RELAX-AHF-type if they met the following criteria: discharge diagnosis of heart failure, systolic blood pressure >125 mm Hg, dyspnea at rest or with mild exertion, intravenous diuretic use, glomerular filtration rate of 30 to 75 mL/min per 1.73 m(2), hemoglobin >8 g/dL, and no use of intravenous inotropes or vasopressors. Baseline characteristics and treatments of RELAX-AHF-type and non-RELAX-AHF-type patients were compared. A Cox model was used to evaluate inpatient mortality. Among both Acute Decompensated Heart Failure National Registry-United States and Acute Decompensated Heart Failure National Registry-International registries, 20.7% (n=38 485) and 16.2% (n=1749) of patients met basic criteria for RELAX-AHF entry, respectively. These patients were more likely to be older, be women, have a previous history of hypertension, have preserved ejection fraction, and have better renal function. In-hospital mortality was lower in RELAX-AHF-type than in non-RELAX-AHF-type patients, even after multivariable adjustment (hazard ratio, 0.59; 95% confidence interval, 0.53-0.66; P<0.0001).

Conclusions: Patients potentially eligible for RELAX-AHF represent ≈2 in 10 patients with AHF in the United States, Latin America, or Asia-Pacific. These patients differ significantly from other hospitalized patients based on clinical characteristics and outcomes.

Keywords: relaxin.

Publication types

  • Comparative Study
  • Multicenter Study
  • Randomized Controlled Trial
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Acute Disease
  • Asia, Southeastern
  • Australia
  • Heart Failure / drug therapy*
  • Heart Failure / epidemiology*
  • Heart Failure / mortality
  • Humans
  • International Cooperation
  • Latin America
  • Patient Selection
  • Population Groups / statistics & numerical data*
  • Recombinant Proteins / administration & dosage
  • Recombinant Proteins / adverse effects
  • Registries / statistics & numerical data*
  • Relaxin / administration & dosage*
  • Relaxin / adverse effects
  • Survival Analysis
  • Treatment Outcome
  • United States


  • Recombinant Proteins
  • serelaxin protein, human
  • Relaxin