Patients with heart failure (HF) and reduced ejection fraction have been researched by the Heart Failure Collaboratory (HFC), resulting in the creation of a score that takes into account the times of the types and amounts of drugs recommended by clinical guidelines. This score has the potential to be used to determine whether or not further benefits are seen from new treatments, even for patients who are already undergoing intensive medical treatment based on established guidelines. The authors studied the efficacy of dapagliflozin according to a modified HFC score in the DAPA-HF trial (Dapagliflozin and prevention of adverse effects in heart failure). Patients with heart failure and reduced ejection fraction were randomly assigned to receive either dapagliflozin or placebo in DAPA-HF. The modified HFC score took into account running and electrocardiogram pace and rate, with a maximum possible score of 100%. HF progression or death from cardiovascular causes was the primary endpoint. The median modified HFC score was 50% (IQR: 27.5% to 62.5%; range 0% to 100%). The highest tertile of the treatment score was associated with a reduced risk of worsening HF or cardiovascular death compared to the lowest tertile (tertile 1, baseline; tertile 2, RR: 0.97 [95% CI: 0.82-1.14]; tertile 3, RR: 0.83 [95% CI: 0.70-0.99]). The risk of HF worsening or cardiovascular death was reduced by dapagliflozin in all tertiles of the treatment score (hazard ratios [HRs] for dapagliflozin versus placebo in tertiles 1-3 were: 0.76 [95% CI: 0.61-0.94]0.76 [95% CI: 0.60-0.97]and 0.71 [95% CI: 0.55-0.90], respectively; Pinteraction = 0.89]. Hospitalization rates for HF decreased, cardiovascular deaths decreased, overall mortality rates decreased, and the Kansas City Cardiomyopathy Questionnaire Total Symptom Score (KCCQ-TTS) improved steadily. Without exception, dapagliflozin outperformed placebo in all domains, independent of the adjusted HFC score. In clinical studies, this score can simply be generated and used to measure the additive effects of new drugs.