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Optimal digoxin range for men is 0.5 to 0.8 ng/mL

J Fam Pract. 2003 May;52(5):349-364
By
Jeffrey Rosenberg, MD
Carol Federiuk, MD, PhD
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  • BACKGROUND: The Digitalis Investigation Group (DIG) trial of patients with heart failure found no effect on mortality from digoxin therapy at serum concentrations of 0.5 to 2.0 ng/mL, but did find that hospitalization due to worsening heart failure was modestly reduced. The original investigators did not evaluate the relative efficacy of different concentrations.
  • POPULATION STUDIED: This reanalysis of data from the DIG trial included 5281 men with stable heart failure recruited from 229 cardiology and 73 primary care sites in the United States and Canada from 1991 to 1995. All participants were in sinus rhythm, had stable and clinically confirmed heart failure, and had a left ventricular ejection fraction of less than 45% as determined by radionuclide, contrast angiography, or 2-dimensional echocardiography.
  • STUDY DESIGN AND VALIDITY: This study is a post-analysis of data collected from the DIG study. The DIG study was a double-blind, placebo-controlled study of digoxin in the treatment of heart failure. Digoxin dosing was based on a published algorithm; serum digoxin levels were drawn 1 month after randomization. The present study is a subgroup analysis of men based on serum drug concentrations at 1 month of 0.5–0.8 ng/mL, 0.9–1.1 ng/mL, or 1.2 ng/mL. These ranges have been used in previous studies of digoxin in the treatment of heart failure.
  • OUTCOMES MEASURED: The primary outcome measure is all-cause mortality at follow-up (mean 37 months, range 24–48 months). Secondary endpoints include death due to cardiovascular causes, death due to worsening congestive heart failure, and hospitalization for worsening heart failure.
  • RESULTS: There was no overall difference in all-cause mortality for patients assigned to placebo as compared with those treated with digoxin (36.2% placebo vs. 36.6% digoxin, P not significant). When separated by serum concentration, however, lower doses of digoxin affected mortality. Patients with serum concentration of 0.5 to 0.8 ng/mL had a 6.3% lower rate (29.9% vs. 36.2%; 95% confidence interval [CI], 2.1%–10.5%; number needed to treat [NNT]= 15) of all-cause mortality and 5.9% lower rate (61.9% vs. 67.8%; 95% CI, 1.5%–10.2%; NNT=17) of hospitalizations compared with placebo.
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PRACTICE RECOMMENDATIONS

The optimal serum drug concentration for digoxin among men in sinus rhythm with stable heart failure is 0.5 to 0.8 ng/mL. This range is associated with decreased risk of hospitalization and mortality compared with placebo. Higher levels are associated with either no reduction, or an increased risk of hospitalization and mortality compared with placebo.

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