The predictive effect of shock index on mortality in patients with acute heart failure

Abstract

Background: The predictive usefulness of the shock index (SI), which is determined as a proportion of heart rate (HR) to systolic blood pressure (SBP), and age-adjusted SI (SI × age) for clinical outcomes other than mortality in acute heart failure (AHF) is not well established. This research aimed to examine whether SI and SI × age measured non-invasively at a patient’s bedside can identify mortality risk in patients admitted to the coronary care unit (CCU) with AHF. Methods: This research was carried out as a retrospective case-control study. Indices were calculated. The receiving operating characteristic (ROC) and Youden index were applied to calculate the optimal SI and SI × age cut-off for estimating mortality. Using multivariate analysis to determine independent indicators of mortality in patients with AHF. Results: A total of 1,468 patients who were hospitalized at the CCU with AHF were included. The population’s median age was 81 (73–91) years and 53.7% were male. In the survivor group, the median SI was 0.6 (0.5–0.75), and the median SI × age was 46 (38–58). In the non-survivor group, the median SI was 0.62 (0.55–0.81) and the median SI × age was 53 (44–66). According to the Youden index, the best value of SI was 0.56 with a specificity of 46% and a sensitivity of 70%, and the best value of SI × age was 44.8 with a specificity of 48% and a sensitivity of 76%. In the multivariate analysis, the power of SI × age to predict mortality was 2.39 times greater than other independent predictors. Conclusions: SI and SI × age calculated in the CCU may be valuable prognostic markers for identifying AHF patients at high risk for adverse outcomes.