Digoxin Helps Prevent Admissions in Patients with CHF
ABSTRACT & COMMENTARY
By Deborah J. DeWaay, MD, FACP
Assistant Professor, Medical University of South Carolina, Charleston, SC
Dr. DeWaay reports no financial relationships in this field of study.
SYNOPSIS: 30-day all-cause hospital admission rates lowered in older patients with chronic systolic heart failure who were started on digoxin when compared to placebo.
There is increasing pressure on hospitals to minimize readmission rates, especially in the Medicare population. Since heart failure is a leading cause of hospital admissions, this population of patients is a key group to focus efforts for decreasing these rates. Research done with the Digitalis Investigation Group (DIG) trial has previously shown that the use of digoxin decreased the readmission rate for heart failure. Bourge and his colleagues used the data collected during this trial to investigate the effect of digoxin on older patients with respect to their all-cause hospital admission rate within 30 days of beginning the drug.
These investigators did a secondary analysis of the DIG trial. In this trial, 6800 older patients (average age 72) with chronic heart failure (EF ≤45%) without arrhythmia were randomized to placebo or digoxin. The study was a double-blind and placebo-controlled trial. Most patients were concurrently receiving angiotensin converting enzyme inhibitors and diuretics. The authors did not know how many patients were taking beta-blockers; however, they make the assumption that beta-blocker use was low since it was not yet approved for use in chronic heart failure at the time of data collection. The primary end point of the original study was all-cause mortality. The primary end point of this analysis was all-cause hospitalization within the first 30 days of being started on digoxin. The baseline characteristics for the patients were similar in both groups, except the digoxin group had a lower body mass index compared to the placebo group. The mean age was 72 years. Twenty-five percent of the group was made up of women, and 11% were nonwhite.
The all-cause admission rate was lower in the digoxin group as compared to placebo, 8.1% and 5.4% respectively [HR 0.66, 95% CI (0.51-0.86); P=0.002]. There was no significant change in the hazard ratio when adjustments were made for baseline characteristics. In addition, digoxin significantly reduced all-cause hospitalization at 60 and 90 days after randomization. In the subgroup analysis, the hazard ratios for the digoxin group were significantly lower when compared to placebo for the following groups: age ≤70, male, white, ischemic cardiomyopathy, pre-trial digoxin use, NYHA class III or IV, EF 25-45%, and cardiothoracic ratio >55%.
Commentary
This study shows promising effects of using digoxin to minimize hospitalizations in older patients. There are few studies that have shown potential benefit regarding decreasing hospitalizations in chronic systolic heart failure patients. This study also demonstrated that the benefit extended to 90 days. In addition, the sub-group analysis showed that patients with prior digoxin use benefited, so it is conceivable that this benefit would continue once the patient was stabilized on digoxin. The authors acknowledge that this population is very different from a hospitalized group of patients; however, they argue that this finding is significant because it shows a medication with promise to help decrease hospitalizations. This study needs to be repeated using patients with chronic heart failure who are being discharged from the hospital to see if the addition or continuation of digoxin decreases all-cause mortality in that population. The study has several weaknesses. First, the patients studied were primarily white males, and females and non-whites did not benefit in the subgroup analysis; therefore generalizability to other populations is difficult. Second, the guidelines recommend that patients with chronic heart failure take beta-blockers. This study was performed on patients not on beta-blockers, so it is unclear how beta-blockers would change the effects of digoxin. Beta-blockers and digoxin, although frequently prescribed together, do have a known drug interaction that results in increased bradycardia. Therefore, further studies need to be done to see if the effects of digoxin are changed in a population that is on beta-blockers. Finally, this study did not investigate whether digoxin decreases readmission rates in patients with chronic heart failure and preserved ejection fraction. Despite the constraints regarding generalizability, digoxin is a drug that could possibly be used to decrease hospital readmission rates in older systolic heart failure patients. Further studies need to be performed to see if digoxin should be added to angiotensin converting enzyme inhibitors and beta-blockers as necessary discharge medications.
