Characterization of hemodynamically stable acute heart failure patients requiring a critical care unit admission: Derivation, validation, and refinement of a risk score

Background Most patients with acute heart failure (AHF) admitted to critical care units (CCUs) are low acuity and do not require CCU-specific therapies, suggesting that they could be managed in a lower-cost ward environment. This study identified the predictors of clinical events and the need for CCU-specific therapies in patients with AHF. Methods Model derivation was performed using data from patients in the ASCEND-HF trial cohort (n=7,141), and the Acute Heart Failure Emergency Management community-based registry (n=666) was used to externally validate the model and to test the incremental prognostic utility of 4 variables (heart failure etiology, troponin, B-type natriuretic peptide [BNP], ejection fraction) using net reclassification index and integrated discrimination improvement. The primary outcome was an in-hospital composite of the requirement for CCU-specific therapies or clinical events. Results The primary composite outcome occurred in 545 (11.4%) derivation cohort participants (n=4,767) and 7 variables were predictors of the primary composite outcome: body mass index, chronic respiratory disease, respiratory rate, resting dyspnea, hemoglobin, sodium, and blood urea nitrogen ( c index=0.633, Hosmer-Lemeshow P =.823). In the validation cohort (n=666), 87 (13.1%) events occurred ( c index=0.629, Hosmer-Lemeshow P =.386) and adding ischemic heart failure, troponin, and B-type natriuretic peptide improved model performance (net reclassification index 0.79, 95% CI 0.046-0.512; integrated discrimination improvement 0.014, 95% CI 0.005-0.0238). The final 10-variable clinical prediction model demonstrated modest discrimination ( c index=0.702) and good calibration (Hosmer-Lemeshow P =.547). Conclusions We derived, validated, and improved upon a clinical prediction model in an international trial and a community-based cohort of AHF. The model has modest discrimination; however, these findings deserve further exploration because they may provide a more accurate means of triaging level of care for patients with AHF who need admission.