Response

Editor – We thank the correspondents for their letter in response to our recent article ‘Drug therapies in older adults (part 2)’.¹ While digoxin is well established in the management of older patients with atrial fibrillation with or without heart failure, the evidence base for digoxin in frail older patients is not established.

The Digitalis Investigation Group study referred to in your letter enrolled 6,800 patients with documented left ventricular ejection fractions of 45% or less.² We are concerned that in this study, as the serum digoxin concentration increased, the absolute risk in mortality rose versus patients receiving placebo. In such patients the absolute mortality rate was 11.8% (95% confidence interval 5.7–18.0%; p < 0.001) higher than those receiving placebo. The effect of frailty on this association is unknown.

We included the section on neprilysin inhibitors to establish that there is a pipeline of newer agents, but we made the point that their role is not established. We agree, however, that we should have included digoxin here discussing its newer roles rather than the indication established described by Sir William Withering. Clinicians managing frailty units should restrict their therapeutic choices to those that have an evidence base in frail patients, or where clinical circumstances are in favour of extrapolating from fitter populations.