Extrapolating Long-term Event-Free and Overall Survival with Dapagliflozin in Patients with Heart Failure and Reduced Ejection Fraction: An Exploratory Analysis of a Phase 3 Randomized Clinical Trial

Importance: Sodium glucose cotransporter 2 inhibitors reduce morbidity and mortality in patients with heart failure and reduced ejection fraction (HFrEF). Clinicians may find estimates of the projected long-term benefits of sodium glucose cotransporter 2 inhibitors a helpful addition to clinical trial results when communicating the benefits of this class of drug to patients. Objective: To estimate the projected long-term treatment effects of dapagliflozin in patients with HFrEF over the duration of a patient's lifetime. Design, Setting, and Participants: Exploratory analysis was performed of Dapagliflozin and Prevention of Adverse Outcomes in Heart Failure (DAPA-HF), a phase 3 randomized, placebo-controlled clinical trial conducted at 410 sites in 20 countries. Patients with an ejection fraction less than or equal to 40% in New York Heart Association functional classification II to IV and elevated plasma levels of N-terminal pro B-type natriuretic peptide were enrolled between February 15, 2017, and August 17, 2018, with final follow-up on June 6, 2019. Mean (SD) duration of follow-up was 17.6 (5.2) months. Interventions: Dapagliflozin, 10 mg, once daily vs placebo in addition to standard therapy. Main Outcomes and Measures: The primary composite outcome was time to first hospitalization for heart failure, urgent heart failure visit requiring intravenous therapy, or cardiovascular death. The trial results were extrapolated to estimate the projected long-term treatment effects of dapagliflozin over the duration of a patient's lifetime for the primary outcome and the secondary outcome of death from any cause. Results: A total of 4744 patients (1109 women [23.4%]; 3635 men [76.6%]) were randomized in DAPA-HF, with a mean (SD) age of 66.3 (10.9) years. The extrapolated mean event-free survival for an individual aged 65 years from a primary composite end point event was 6.2 years for placebo and 8.3 years for dapagliflozin, representing an event-free survival time gain of 2.1 years (95% CI, 0.8-3.3 years; P =.002). When considering death from any cause, mean extrapolated life expectancy for an individual aged 65 years was 9.1 years for placebo and 10.8 years for dapagliflozin, with a gain in survival of 1.7 years (95% CI, 0.1-3.3; P =.03) with dapagliflozin. Similar results were seen when extrapolated across the age range studied. In analyses of subgroups of patients in DAPA-HF, consistent benefits were seen with dapagliflozin on both event-free and overall survival. Conclusions and Relevance: These findings indicate that dapagliflozin provides clinically meaningful gains in extrapolated event-free and overall survival. These findings may be helpful in communicating the benefits of this treatment to patients with HFrEF. Trial Registration: ClinicalTrials.gov Identifier: NCT03036124.