Why different trials on digitalis give conflicting data

Use of public datasets in the examination of multimorbidity: Opportunities and challenges

The interrogation of established, large-scale datasets presents great opportunities in health data science for the linkage and mining of potentially disparate resources to create new knowledge in a fast and cost-efficient manner. The number of datasets that can be queried in the field of multimorbidity is vast, ranging from national administrative and audit datasets, large clinical, technical and biological cohorts, through to more bespoke data collections made available by individual organisations and laboratories. However, with these opportunities also come technical and regulatory challenges that require an informed approach. In this review, we outline the potential benefits of using previously collected data as a vehicle for research activity. We illustrate the added value of combining potentially disparate datasets to find answers to novel questions in the field. We focus on the legal, governance and logistical considerations required to hold and analyse data acquired from disparate sources and outline some of the solutions to these challenges. We discuss the infrastructure resources required and the essential considerations in data curation and informatics management, and briefly discuss some of the analysis approaches currently used.

Digitalis and heart failure: does digitalis really produce beneficial effects through a positive inotropic action?

Although digitalis was introduced to medicine long ago, the drug is still extensively used in clinical practice today. Opinions on its mechanism of action have undergone much change in the course of time, and the way in which cardiovascular effects are produced is still not completely clear. Limitations and contraindications for the use of digitalis substances are reported, especially in the treatment of ischemic heart disease. Preliminary data regarding the effects of digitalis on the diastolic phase are unfavorable, although the relationship between digitalis and diastolic function ought to be studied in greater depth in various clinical conditions. In spite of many recent trials, the old question of the usefulness of digitalis in the chronic treatment of patients in sinus rhythm and heart failure is still debated. An important clinical benefit in the chronic use of digitalis appears restricted to a relatively small proportion of patients with severe congestive heart failure, while in the majority of chronically treated subjects the effects of the drug are scanty or insignificant. The beneficial effect of digitalis used chronically is essentially believed to be due to its positive inotropic action. Since the vagomimetic and the antiadrenergic effects of digitalis have been demonstrated to be independent from its inotropic action, they could be considered determinants of the clinical benefits of digitalis. These indirect effects may be useful in the control of the negative neuroendocrine response developing during congestive heart failure. Thus the statement that digitalis is essentially an inotropic agent seems restrictive; its definition should reflect the favorable effects obtained in some cases of congestive heart failure rather than its various and contrasting underlying mechanisms of action.

Review of randomized trials of digoxin therapy in patients with chronic heart failure

Although digitalis glycosides were introduced in the treatment of cardiac maladies greater than 200 years ago, controversy persists regarding the precise role of digoxin in any multidrug approach to the treatment of congestive heart failure (CHF). Despite its widespread use for more than 2 centuries, only recently have double-blind, randomized, placebo-controlled trials of digoxin therapy been conducted in patients with moderate CHF and sinus rhythm. These trials demonstrate that digoxin is superior to placebo in improving left ventricular (LV) ejection fraction, increasing exercise capacity, and preventing CHF worsening. Digoxin produces benefits similar to those seen with angiotensin converting enzyme (ACE) inhibitors with regard to clinical compensation and improvement in LV function. However, improved survival is demonstrated only in response to ACE inhibitors. The recently completed RADIANCE study addresses the value of combining digoxin with ACE inhibitor therapy in patients with mild-to-moderate CHF. Because increased mortality has been reported with the newer oral inotropic agents, it currently appears that digoxin is the only oral inotropic agent useful in clinical practice in the treatment of CHF. However, the effects of digoxin on mortality in patients with CHF remain unknown. In the large, double-blind, randomized trial conducted by the National Heart, Lung, and Blood Institute, the effects of digoxin on mortality in patients with CHF and already being treated with ACE inhibitors are currently being evaluated. Presently, based on the results of placebo-controlled studies, it appears that digoxin, alone or in combination with ACE inhibitors, is beneficial in patients with any signs or symptoms of CHF due to systolic LV dysfunction.

To what extent do congestive heart failure patients in sinus rhythm benefit from digoxin therapy? A systematic overview and meta-analysis

PURPOSE

To reappraise the effectiveness of digoxin for the treatment of congestive heart failure (CHF) in patients with sinus rhythm in light of data from recently published randomized controlled trials and to quantitatively assess its usefulness.

STUDY IDENTIFICATION

Computerized searches of the MEDLINE database were performed, and the reference list of each retrieved article was reviewed.

STUDY SELECTION

Review of more than 360 citations and the reference lists of 19 review articles and 61 potentially relevant articles revealed seven double-blind randomized controlled trials that were included in this overview.

DATA EXTRACTION

Study quality was assessed and descriptive information concerning the study populations, the specific interventions, and clinically relevant outcome measurements was extracted.

RESULTS OF DATA SYNTHESIS

The common odds ratio for CHF deterioration while receiving digoxin versus placebo was 0.28, with a 95% confidence interval of 0.16 to 0.49. Predictors of digoxin benefit included presence of a third heart sound and the severity and duration of CHF.

CONCLUSION

Data from seven trials of high methodologic quality suggest that, on average, one out of nine patients with CHF and sinus rhythm derive a clinically important benefit from digoxin (with a 95% confidence interval of 1/33 to 1/5).