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-imple-mentation. 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 post-implementation (P < 0.001). Overall pulmonary embolism imaging yield rates rose from 9.9% to 16.5% (P < 0.001). A total of 179 pre-implementation pulmonary embolisms were identified, with an incidence of 1.4 per 1000 presentations. This compared to 184 pulmonary embolisms post-implementation, 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 age-adjusted 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.