Does telephone triage of emergency (999) calls using advanced medical priority dispatch (AMPDS) with Department of Health (DH) call prioritisation effectively identify patients with an acute coronary syndrome? An audit of 42 657 emergency calls to Hampshire Ambulance Service NHS Trust

Introduction: The National Service Framework for Coronary Heart Disease requires identification of patients with an acute coronary syndrome (ACS) to enable prompt identification of those who may subsequently require pre-hospital thrombolysis. The Advanced Medical Priority Despatch System (AMPDS) with Department of Health (DH) call prioritisation is now the common triage tool for emergency ('999') calls in the UK. We retrospectively examined patients with ACS to identify whether this triage tool had been able to allocate an appropriate emergency response. Methods: All emergency calls to Hampshire Ambulance Service NHS Trust (HAST) from the Southampton area over an 8 month period (January to August 2004) were analysed. The classification allocated to the patient by AMPDS (version 10.4) was specifically identified. Data from the Myocardial Infarct National Audit Project) were obtained from the receiving hospital in Southampton to identify the actual number of patients with a true ACS. Results: In total, 42 657 emergency calls were made to HAST from the Southampton area. Of these, 263 patients were subsequently diagnosed in hospital as having an ACS. Of these 263 patients, 76 presented without chest pain. Sensitivity of AMPDS for detecting ACS in this sample was 71.1% and specificity 92.5%. Positive predictive value was 5.6% (95% confidence interval 4.8 to 6.4%), and 12.5% (33/263) of patients with confirmed ACS were classified as non-life threatening (category B) incidents. Conclusion: Only one of approximately every 18 patients with chest pain has an ACS. AMPDS with DH call prioritisation is not a tool designed for clinical diagnosis, and its extension into this field does not enable accurate identification of patients with ACS.