The objectives were to determine the impact of frailty and disability on 30-day mortality and whether the addition of these variables to HFRSS EFFECT risk score (FBI-EFFECT model) improves the short-term mortality predictive capacity of both HFRSS EFFECT and BI-EFFECT models in older patients with acute decompensated heart failure (ADHF) atended in the emergency department. We performed a retrospective analysis of OAK Registry including all consecutive patients ≥65 years old with ADHF attended in 3 Spanish emergency departments over 4 months. FBI-EFFECT model was developed by adjusting probabilities of HFRSS EFFECT risk categories according to the 6 groups (G1: non frail, no or mildly dependent; G2: frail, no or mildly dependent; G3: non frail, moderately dependent; G4: frail, moderately dependent; G5: severely dependent; G6: very severely dependent).We included 596 patients (mean age: 83 SD7; 61.2% females). The 30-day mortality was 11.6% with statistically significant differences in the 6 groups (p < 0.001). After adjusting for HFRSS EFFECT risk categories, we observed a progressive increase in hazard ratios from groups G2 to G6 compared with G1 (reference). FBI-EFFECT had a better prognostic accuracy than did HFRSS EFFECT (log-rank p < 0.001; Net Reclassification Improvement NRI = 0.355; p < 0.001; Integrated Discrimination Improvement IDI = 0.052; p ;< 0.001) and BI-EFFECT (log-rank p = 0.067; NRI = 0.210; p = 0.033; IDI = 0.017; p = 0.026). In conclusion, severe disability and frailty in patients with moderate disability are associated with 30-day mortality in ADHF, providing additional value to HFRSS EFFECT model in predicting short-term prognosis and establishing a care plan.