Decision tool for high risk and low risk assessment groups*. See the attached file Figure 1 and Figure 2. * Use of diagnostic tests (%) is calculated with respect to the number of attendances **Risk assessment in 35% of the patients presented with suspected PE may or may not have occurred but did not involve completion of risk assessment cards containing the structured decision tool. With respect to these patients it is uncertain whether the use of diagnostic resources has been influenced by the rules outlined in the protocol. ***During the intervention period an assessment involving a structured decision tool was performed on 513 (65%) of attendances although a valid assessmentof low or high risk was only attained for 491 (62%) attendances due to the incomplete answers to six questions concerning physiological parameters andmedical history that are recorded on the specially designed assessment card. This resulted in the uncertain outcome of the assessment for 22 (2%) attendances.