­­­­Optimal Glucose and Stress-hyperglycaemia Ratio Cut-off Values for Predicting 1-year Mortality in Diabetic and Non-diabetic Acute Myocardial Infarction Patients

Abstract

Background Stress-induced hyperglycaemia at time of hospital admission has been linked to worse prognosis following acute myocardial infarction (AMI). The stress-hyperglycaemia ratio (SHR) index normalises the acute increase in blood glucose values to background glycaemic status. However, the optimal cut-off blood glucose and SHR values for predicting adverse outcomes post-AMI are unknown. As such, we determined the optimal blood glucose and SHR cut-offs for predicting 1-year all cause mortality in diabetic and non-diabetic non-ST-segment elevation myocardial infarction (NSTEMI) and ST-segment elevation myocardial infarction (STEMI) patients. Methods We undertook a national, registry-based study of patients with AMI from January 2008 to December 2015. We determined the optimal blood glucose and SHR cut-off values using the Youden’s formula for 1-year all-cause mortality. We subsequently analyzed the sensitivity, specificity, positive and negative predictive values of the cut-offs in the diabetic and non-diabetic subgroups, stratified by the type of AMI. Results There were 5,841 STEMI and 4,105 NSTEMI in the study. In STEMI patients, both glucose and SHR were independent predictors of 1-year all-cause mortality [Glucose: OR 2.19 (95% CI 1.74–2.75); SHR: 2.19 (95% CI 1.73–2.78)]. However, in NSTEMI patients, glucose and SHR were not independently associated with 1-year all-cause mortality [Glucose: OR 1.37 (95% CI 1.00-1.89); SHR: 1.27 (95% CI 0.91–1.78)]. In STEMI patients, ROC analysis showed that SHR performed better than glucose (AUC for glucose 0.633 versus AUC for SHR 0.692, P < 0.001) in diabetic patients, whereas in non-diabetic patients, SHR and glucose performed equally well (AUC for glucose 0.720 versus AUC for SHR 0.717, P < 0.664). The optimal glucose cut-off values were 15.0mmol/L for diabetic STEMI patients and 11mmol/L for non-diabetic STEMI patients and the corresponding optimal cut-off values for SHR were 1.7 and 1.5, respectively. Conclusions Glucose on admission and SHR were independent predictors of 1-year all-cause mortality in STEMI, whereas this was not the case in NSTEMI patients. In STEMI setting, SHR performed better than admission glucose to predict 1-year all-cause mortality in diabetic patients, whereas in non-diabetic patients both SHR and glucose performed equally well.