PEAL Score to Predict the Mortality Risk of Cardiogenic Shock in the Emergency Department: An Observational Study

Abstract

Background: The in-hospital mortality of cardiogenic shock (CS) remains high (28% to 45%). As a result, several studies developed prediction models to assess the mortality risk and provide guidance on treatment, including CardShock and IABP-SHOCK II scores, which performed modestly in external validation studies, reflecting the heterogeneity of the CS populations. Few articles established predictive scores of CS based on Asian people with a higher burden of comorbidities than Caucasians. We aimed to describe the clinical characteristics of a contemporary Asian population with CS, identify risk factors, and develop a predictive scoring model.

Methods: A retrospective observational study was conducted between 2014 and 2019 to collect the patients who presented with all-cause CS in the emergency department of a single medical center in Taiwan. We divided patients into subgroups of CS related to acute myocardial infarction (AMI-CS) or heart failure (HF-CS). The outcome was all-cause 30-day mortality. We built the prediction model based on the hazard ratio of significant variables, and the cutoff point of each predictor was determined using the Youden index. We also assessed the discrimination ability of the risk score using the area under a receiver operating characteristic curve.

Results: We enrolled 225 patients with CS. One hundred and seven patients (47.6%) were due to AMI-CS, and ninety-eight patients among them received reperfusion therapy. Forty-nine patients (21.8%) eventually died within 30 days. Fifty-three patients (23.55%) presented with platelet counts < 155 × 10³/μL, which were negatively associated with a 30-day mortality of CS in the restrictive cubic spline plot, even within the normal range of platelet counts. We identified four predictors: platelet counts < 200 × 10³/μL (HR 2.574, 95% CI 1.379-4.805, p = 0.003), left ventricular ejection fraction (LVEF) < 40% (HR 2.613, 95% CI 1.020-6.692, p = 0.045), age > 71 years (HR 2.452, 95% CI 1.327-4.531, p = 0.004), and lactate > 2.7 mmol/L (HR 1.967, 95% CI 1.069-3.620, p = 0.030). The risk score ended with a maximum of 5 points and showed an AUC (95% CI) of 0.774 (0.705-0.843) for all patients, 0.781 (0.678-0.883), and 0.759 (0.662-0.855) for AMI-CS and HF-CS sub-groups, respectively, all p < 0.001.

Conclusions: Based on four parameters, platelet counts, LVEF, age, and lactate (PEAL), this model showed a good predictive performance for all-cause mortality at 30 days in the all patients, AMI-CS, and HF-CS subgroups. The restrictive cubic spline plot showed a significantly negative correlation between initial platelet counts and 30-day mortality risk in the AMI-CS and HF-CS subgroups.

Keywords: acute myocardial infarction; cardiogenic shock; mortality risk; platelet counts; score.

Figure 1

The restricted cubic spline plot shows hazard ratios with 95% confidence intervals for mortality in 30 days according to platelet counts. The plot was fitted with the Cox proportional hazards model, adjusting for age, sex, body mass index, heart rate, and left ventricular ejection fraction. The cut-off point of platelet counts was 200 × 10³/μL. The shades of grey color presented the 95% confidence intervals of hazard ratios.

Figure 2

The receiver operating characteristic curve (ROC) of the risk score to predict mortality risk at 30 days in all patients with CS (n = 225) (A). The ROC of the risk score to predict mortality risk at 30 days in the AMI-CS subgroup (n = 107) (B). The ROC of the risk score to predict mortality risk at 30 days in the HF-CS subgroup (n = 118) (C). The blue lines indicated the curves in the AUC of the ROC for all patients (A), ACS patients (B), and Non-ACS patients (C). The green lines presented the baseline in the AUC of the ROC.

Figure 3

Distribution of the study population (red line) and mortality rate observed at 30 days (%; blue bars) across the cumulative points of the risk score.

Figure 4

Kaplan–Meier survival curve for 30-day mortality according to score categories with pair-wise comparisons by log-rank test.