Effect of a clinical flowchart incorporating Wells score, PERC rule and age-adjusted D-dimer on pulmonary embolism diagnosis, scan rates and diagnostic yield

Objective: To assess the association between the use of a flowchart incorporating Wells score, PERC rule and age-adjusted D-dimer and subsequent imaging and yield rates of computed tomography pulmonary angiogram and nuclear medicine ventilation perfusion scans being ordered in the ED for the assessment of pulmonary embolism. Methods: A flowchart governing ED pulmonary embolism investigation was introduced across three EDs in Melbourne, Australia for a 12 month period. Comparison of pulmonary embolism imaging rates and yield with the preceding 12 months was performed. Results: A total of 1815 pre-implementation scans were performed compared with 1116 scans post-implementation. Because of growth in patient attendances over this time, this equated to an imaging rate of 14.5 per 1000 presentations pre-implementation and 8.6 per 1000 presentations postimplementation (P < 0.001). Overall pulmonary embolism imaging yield rates rose from 9.9% to 16.5% (P < 0.001). A total of 179 preimplementation pulmonary embolisms were identified, with an incidence of 1.4 per 1000 presentations. This compared to 184 pulmonary embolisms postimplementation, with an incidence of 1.4 per 1000 presentations (P = 0.994). Conclusion: The introduction of a clinical flowchart incorporating Wells score, PERC rule and ageadjusted D-dimer was associated with an increase in ED computed tomography pulmonary angiogram and nuclear medicine ventilation perfusion yield rate from 9.9% to 16.5% across the three enrolment hospitals when investigating possible pulmonary embolism. This corresponded to a 40% relative reduction in pulmonary embolism imaging. Diagnosis rates remained unchanged and no cases of missed pulmonary embolism attributable to the flowchart were identified.