Search

Aims Treatment 'effects' are often inferred from non-randomized and observational studies. These studies have inherent biases and limitations, which may make therapeutic inferences based on their results unreliable. We compared the conflicting findings of these studies to those of prospective randomized controlled trials (RCTs) in relation to pharmacological treatments for heart failure (HF). Methods and results We searched Medline and Embase to identify studies of the association between non-randomized drug therapy and all-cause mortality in patients with HF until 31 December 2017. The treatments of interest were: angiotensin-converting enzyme inhibitors, angiotensin receptor blockers, beta-blockers, mineralocorticoid receptor antagonists (MRAs), statins, and digoxin. We compared the findings of these observational studies with those of relevant RCTs. We identified 92 publications, reporting 94 non-randomized studies, describing 158 estimates of the 'effect' of the six treatments of interest on all-cause mortality, i.e. some studies examined more than one treatment and/or HF phenotype. These six treatments had been tested in 25 RCTs. For example, two pivotal RCTs showed that MRAs reduced mortality in patients with HF with reduced ejection fraction. However, only one of 12 non-randomized studies found that MRAs were of benefit, with 10 finding a neutral effect, and one a harmful effect. Conclusion This comprehensive comparison of studies of non-randomized data with the findings of RCTs in HF shows that it is not possible to make reliable therapeutic inferences from observational associations. While trials undoubtedly leave gaps in evidence and enrol selected participants, they clearly remain the best guide to the treatment of patients. [ABSTRACT FROM AUTHOR]

Aims: To evaluate the effects of digoxin in patients with the newly described phenotype of heart failure (HF) and mid-range ejection fraction (HFmrEF), attributed to mild left ventricular systolic dysfunction.Methods and Results: We carried out a retrospective analysis of the Digitalis Investigation Group (DIG) trial which had 7788 patients available for analysis with a left ventricular ejection fraction (LVEF) ranging between 3% and 85%. We compared the effect of digoxin to placebo in three mutually exclusive groups of patients defined by LVEF category: <40% (HF with reduced LVEF, HFrEF, n = 5874), 40-49% (HFmrEF, n = 1195) and ≥50% (HF with preserved LVEF, HFpEF, n = 719). The primary outcome was the composite of cardiovascular death or HF hospitalisation. Patients with HFmrEF resembled patients with HFrEF, more than those with HFpEF, with respect to age, sex and aetiology but were more like HFpEF patients with respect to blood pressure and the prevalence of hypertension. Event rates in patients with HFmrEF were similar to those in HFpEF and much lower than in HFrEF. Digoxin reduced the primary endpoint in patients with HFrEF, mainly due to reduced HF hospitalisation: the digoxin/placebo hazard ratio (HR) for HF hospitalisation was 0.71 [95% confidence interval (CI) 0.65-0.77]. The digoxin/placebo HR for HF hospitalisation in patients with HFmrEF was 0.80 (95% CI 0.63-1.03) and 0.85 (95% CI 0.62-1.17) in those with HFpEF. The digoxin/placebo HR for the composite of HF death or HF hospitalisation was 0.74 (95% CI 0.68-0.81) in HFrEF, 0.83 (95% CI 0.66-1.05) in HFmrEF and 0.88 (95% CI 0.65-1.19) in HFpEF.Conclusions: In this study, event rates in patients with HFmrEF were closer to those in HFpEF than HFrEF. Digoxin had most effect on HF hospitalisation in patients with HFrEF, an intermediate effect in HFmrEF, and the smallest effect in HFpEF. [ABSTRACT FROM AUTHOR]