Using DIG Trial to Examine The Association Between Digoxin Therapy and Clinical Outcomes in Heart Failure: A Subgroup and 1-Year Analysis

This study evaluated the association between digoxin therapy and the composite outcome of all-cause mortality or hospitalization due to worsening heart failure. Patients with reduced election fractions (HFrEF) were obtained from the Digitails Investigation Group trials. Baseline characteristics were summarized by left ventricular ejection fraction (LVEF) subgroup and treatment group. This study used Cox proportional hazards models to examine treatment-by-subgroup interactions within the first year and to estimate subgroup-specific hazard ratios during both full and 1-year follow-up. Results showed that there is an association between digoxin therapy and a lower hazard composite outcome across LVEF and NYHA subgroups, with stronger numerical associations during the first-year follow-up period. However, there were no statistically significant interactions for LVEF, NYHA class, cardiothoracic ratio, and prior digoxin use. These findings indicate a consistent protective association across these examined subgroups, and a stronger early association could be interpreted cautiously because there is no formal evidence of significant effect modification found.