Baseline Hemoglobin and Creatinine Clearance Composite Index in STEMI
Baseline Hemoglobin and Creatinine Clearance Composite Index in STEMI
Background: Hemoglobin (Hgb) and creatinine clearance (CrCl) are readily-available, routinely-obtained laboratory parameters that predict acute coronary syndrome outcomes. We sought to develop a laboratory index (LI) to predict early mortality in ST-elevation myocardial infarction (STEMI) and determine the additional risk stratification offered by adding the LI to the TIMI Risk Score (TRS) for STEMI.
Methods and Results: The association between Hgb and CrCl values obtained at hospitalization and 30-day mortality was evaluated in 14,373 STEMI patients undergoing fibrinolysis in Intravenous NPA for the Treatment of Infarcting Myocardium Early II-Thrombolysis In Myocardial Infarction-17 (InTIME II-TIMI 17). Logistic regression models determined the optimal combination of laboratory variables into a LI. Prognostic utility of the LI was validated in 18,427 STEMI patients from Enoxaparin and Thrombolysis Reperfusion for Acute Myocardial Infarction Treatment (ExTRACT)-TIMI 25. In InTIME II, Hgb levels < 15.0 g/dL and CrCl < 100 mL/min were significantly and independently associated with increased risk of death (ORadj 1.22, 95% CI 1.15-1.29 for each 1 g/dL decrease in Hgb, P < .001, and ORadj 1.23, 95% CI 1.17-1.29 for each 10 mL/min decrease in CrCl, P < .001, respectively). In multivariable analysis, the optimal weighting of Hgb and CrCl to form an LI to predict mortality was (15-Hgb) + (100-CrCl)/8. The LI revealed a 10-fold increase in death across prespecified groups (P < .001). The LI offered additional risk stratification across all TRS groups and improved the discriminatory ability of the TRS (c-statistic from 0.755 to 0.789, P < .001). External validation in ExTRACT showed similar enhancement of the prognostic capacity of the TRS (c-statistic from 0.747 to 0.777, P < .001).
Conclusions: The LI is a simple, powerful tool to predict death in STEMI, either separately or with the TRS.
Stratification of risk is an important step in the evaluation of patients with ST-elevation myocardial infarction (STEMI). Prognostic information provided by risk scores help guide medical management, including triage to the appropriate level of care and use of hospital resources. The TIMI risk score (TRS) for STEMI is a convenient bedside score based on clinical variables developed for assessment of mortality risk in the prehospital setting or upon hospital arrival. The predictive capacity of the TRS has been validated in diverse populations.
We have shown that lower hemoglobin (Hgb) levels at hospital arrival are associated with major adverse cardiovascular events in acute coronary syndromes. Similarly, impaired renal function characterized by reduced baseline creatinine clearance (CrCl) is independently associated with increased mortality in STEMI patients treated with fibrinolysis or primary angioplasty. Therefore, we combined these readily available and routinely obtained laboratory tests into a single laboratory index (LI) and determined the relationship between the LI and the early outcomes of patients admitted to the hospital with STEMI. We have also evaluated the effect of combining the LI with the TRS on risk stratification. Lastly, we validated our findings in an independent cohort of STEMI patients.
Abstract and Introduction
Abstract
Background: Hemoglobin (Hgb) and creatinine clearance (CrCl) are readily-available, routinely-obtained laboratory parameters that predict acute coronary syndrome outcomes. We sought to develop a laboratory index (LI) to predict early mortality in ST-elevation myocardial infarction (STEMI) and determine the additional risk stratification offered by adding the LI to the TIMI Risk Score (TRS) for STEMI.
Methods and Results: The association between Hgb and CrCl values obtained at hospitalization and 30-day mortality was evaluated in 14,373 STEMI patients undergoing fibrinolysis in Intravenous NPA for the Treatment of Infarcting Myocardium Early II-Thrombolysis In Myocardial Infarction-17 (InTIME II-TIMI 17). Logistic regression models determined the optimal combination of laboratory variables into a LI. Prognostic utility of the LI was validated in 18,427 STEMI patients from Enoxaparin and Thrombolysis Reperfusion for Acute Myocardial Infarction Treatment (ExTRACT)-TIMI 25. In InTIME II, Hgb levels < 15.0 g/dL and CrCl < 100 mL/min were significantly and independently associated with increased risk of death (ORadj 1.22, 95% CI 1.15-1.29 for each 1 g/dL decrease in Hgb, P < .001, and ORadj 1.23, 95% CI 1.17-1.29 for each 10 mL/min decrease in CrCl, P < .001, respectively). In multivariable analysis, the optimal weighting of Hgb and CrCl to form an LI to predict mortality was (15-Hgb) + (100-CrCl)/8. The LI revealed a 10-fold increase in death across prespecified groups (P < .001). The LI offered additional risk stratification across all TRS groups and improved the discriminatory ability of the TRS (c-statistic from 0.755 to 0.789, P < .001). External validation in ExTRACT showed similar enhancement of the prognostic capacity of the TRS (c-statistic from 0.747 to 0.777, P < .001).
Conclusions: The LI is a simple, powerful tool to predict death in STEMI, either separately or with the TRS.
Introduction
Stratification of risk is an important step in the evaluation of patients with ST-elevation myocardial infarction (STEMI). Prognostic information provided by risk scores help guide medical management, including triage to the appropriate level of care and use of hospital resources. The TIMI risk score (TRS) for STEMI is a convenient bedside score based on clinical variables developed for assessment of mortality risk in the prehospital setting or upon hospital arrival. The predictive capacity of the TRS has been validated in diverse populations.
We have shown that lower hemoglobin (Hgb) levels at hospital arrival are associated with major adverse cardiovascular events in acute coronary syndromes. Similarly, impaired renal function characterized by reduced baseline creatinine clearance (CrCl) is independently associated with increased mortality in STEMI patients treated with fibrinolysis or primary angioplasty. Therefore, we combined these readily available and routinely obtained laboratory tests into a single laboratory index (LI) and determined the relationship between the LI and the early outcomes of patients admitted to the hospital with STEMI. We have also evaluated the effect of combining the LI with the TRS on risk stratification. Lastly, we validated our findings in an independent cohort of STEMI patients.