A clinical scoring system in undifferentiated chest pain predicting undetectable troponin concentration.

Background: Chest pain is the most common reason for emergency admission to hospital, but the majority of these are due to non-cardiac pain. We sought to determine which combination of clinical features is more likely to predict an undetectable troponin level in patients presenting with chest pain.
Methods: We collected data over a two-month period on consecutive patients presenting acutely to hospital with chest pain and who had a troponin I measured. We recorded basic demographics, risk factors, pain distribution, associated symptoms, physical findings and ECG changes. The parameters significantly associated with troponin positivity were entered into a stepwise logistic regression analysis and the resulting model's coefficients were used to construct a simple clinical score to categorise patients into low, medium or high probability of having a positive troponin.
Results: 26 of 157 (16.6%) patients had a positive troponin. The variables retained in the regression model were: age >65, heart rate >80, previous myocardial infarction, diabetes and pain radiating to either arm. The model showed good discrimination (area under ROC curve 0.869, 95% CI 0.806 - 0.917). Using the regression model's coefficients, patients were grouped into low, intermediate or high probability groups. Being in the low probability group had a negative predictive value of 97.8% and being in the high probability group had a positive predictive value of 65.2%. The majority (73.9%) of patients could be categorised as either low or high probability.
Discussion: This simple scoring system, if prospectively validated, may be useful in identifying low risk patients with chest pain who are unlikely to have elevation of serum troponin concentration.