Effect of age on mortality, hospitalizations and response to digoxin in patients with heart failure: The DIG study

OBJECTIVES This study was designed to determine the effect of increasing ag e on mortality, hospitalizations and digoxin side effects in patients with heart failure (HF), and to determine whether the effect of digoxin on clini cal outcomes varies as a function of age. BACKGROUND The incidence and prevalence of HF increase with advancing age, but there are limited data on the clinical course and response to specific therapeutic interventions in elderly patients with HF. METHODS The Digitalis Investigation Group (DIG) study was a prospective, ra ndomized clinical trial involving 7,788 patients with HF randomized to digo xin or placebo and followed for an average of 37 months. In the present ana lysis, patients were stratified into five age categories: < 50 years (n = 8 41), 50 to 59 years (n = 1,545), 60 to 69 years (n = 2,885), 70 to 79 years (n = 2,092) and greater than or equal to 80 years (n = 425). Interactions between age and the following clinical outcomes were examined: total mortal ity, all-cause hospitalizations, HF hospitalizations, the composite of HF d eath or HF hospitalization, hospitalization for suspected digoxin toxicity and withdrawal from therapy because of side effects. RESULTS Increasing age was an independent risk factor for total mortality, all-cause hospitalization, HF hospitalization, HF death or hospital admissi on, hospitalization for suspected digoxin toxicity and withdrawal from digo xin therapy (all p < 0.001). However, there were no significant interaction s between age and digoxin treatment with respect to any of the major clinic al end points. CONCLUSIONS Increasing age is associated with progressively worse clinical outcomes in patients with HF. However, the beneficial effects of digoxin in reducing all-cause admissions, HF admissions, and HF death or hospitalizat ion are independent of age. Thus, digoxin remains a useful agent for the ad junctive treatment of HF due to impaired left ventricular systolic function in patients of all ages. (C) 2001 by the American College of Cardiology.