[Clinical significance of early troponin I levels on the prognosis of patients with severe heat stroke].

OBJECTIVE

To investigate the clinical significance of early troponin I (TnI) level in the prognosis of severe heat stroke.

METHODS

Clinical data of 131 patients with severe heat stroke in the intensive care unit (ICU) of the Affiliated Changzhou NO.2 People's Hospital of Nanjing Medical University (study dataset) and ICU 67 patients with severe heat stroke in Jintan First People's Hospital of Changzhou (validation dataset) were retrospectively analyzed from June 2013 to September 2022. The patients were divided into survival group and death group according to 30-day outcomes. TnI was collected within 24 hours after admission to the emergency department. Cox regression analysis was performed to analyze the risk factors of severe heat stroke death. Spearman correlation test was used to analyze the correlation between TnI and heart rate, and peripheral systolic blood pressure. The receiver operator characteristic curve (ROC curve) was drawn to evaluate the predictive value of TnI for death in patients with severe heat stroke. Decision curve analysis (DCA) was conducted to assess the clinical net benefit rate of TnI prediction. Grouping by TnI cut-off value, Kaplan-Meier survival curve was used to analyze 30-day cumulative survival. Sensitivity analysis included modified Possion regression, E-value, and subgroup forest map was used to evaluate the mortality risk of TnI in different populations. External dataset was used to verify the predictive value of TnI.

RESULTS

The death group had significantly higher TnI compared to the survival group [μg/L: 0.623 (0.196, 1.510) vs. 0.084 (0.019, 0.285), P < 0.01]. Multivariate Cox regression analysis after adjusting for confounding factors showed that TnI was an independent risk factor for death [hazard ratio (HR) = 1.885, 95% confidence interval (95%CI) was 1.528-2.325,P < 0.001]. Spearman correlation test showed that TnI was positively correlated with heart rate (r = 0.537, P < 0.001) and negatively correlated with peripheral systolic blood pressure (r = -0.611, P < 0.001). ROC curve showed that the area under the curve (AUC) of the TnI (0.817) was better than that of the acute physiology and chronic health evaluation II (APACHE II, 0.756). The DCA curve showed that the range of clinical net benefit rate of TnI (6.21%-20.00%) was higher than that of APACHE II score (5.14%-20.00%). Kaplan-Meier survival curve showed that patients in the low-risk group (TnI ≤ 0.106) had a significantly higher 30-day survival rate than that in the high-risk group (TnI > 0.106) group (Log-Rank test: χ = 17.350, P < 0.001). Modified Possion regression with adjustment for confounding factors showed that TnI was still an independent risk factor for death in patients with severe heat stroke [relative risk (RR) = 1.425, 95%CI was 1.284-1.583, P < 0.001]. The E-value was 2.215. The subgroup forest plot showed that the risk factors of TnI were obvious in male patients and patients ≤ 60 years old (male: HR = 1.731, 95%CI was 1.402-2.138, P < 0.001; ≤ 60 years old: HR = 1.651, 95%CI was 1.362-2.012, P < 0.001). In the validation dataset, ROC curve analysis showed that the AUC (0.836) of TnI predicting the prognosis of severe heat stroke was still higher than the APACHE II score (0.763).

CONCLUSIONS

Early elevation of TnI is a high-risk factor for death in patients with severe heat stroke, and it has a good predictive value for death.