Kerstin de Wit: Making clinical decisions in the era of clinical decision rules


Emergency department physicians are frequently criticized for using CT pulmonary angiography testing more frequently than they should. International pulmonary embolism guidelines recommend using a structured clinical probability estimate such as the Wells score, in combination with D-dimer, to rule out pulmonary embolism in the emergency department. However, these rules were not derived for use in the emergency department, and there has been little research identifying opportunities and barriers to evidence-based diagnosis of pulmonary embolism in this environment.


This is a mixed method research program which is identifying common diagnostic pathways for pulmonary embolism in the emergency department, barriers to using clinical decision rules and opportunities to standardize the diagnostic process. The program will identify an improved pathway for diagnosing pulmonary embolism which will be tested for feasibility.

There are multiple sub-studies within this program and one sub-study, ‘Making clinical decisions in the era of clinical decision rules’ was presented at NCER 2017. This is a qualitative interview study with three steps. First the physician recalls a time when they tested a patient for pulmonary embolism. Next, they watch a simulated video of a patient with chest pain, being interviewed by a medical student. Following this, they draw a mind map and talk through the process of testing the patient for pulmonary embolism. Lastly, they answer a knowledge quiz on the PERC, Wells and age-adjusted D-dimer rules.

Progress to date

These interviews are being conducted at 5 cities in Canada. To date, we have completed 16 interviews in Hamilton, 15 in Toronto and 11 in Montreal. We have ethics approval to start recruitment in Vancouver and are waiting for ethics approval in Ottawa. We aim to have completed the interviews by June 2018 with analysis complete by December 2018.

Other sub-studies in progress:

  1. Interviews with emergency physicians who deviate from diagnostic pulmonary embolism protocol.
  2. A chart extraction is in process to prepare a database which will compare patient, environmental and physician characteristics when diagnostic pulmonary embolism protocol was and was not followed.
  3. A systematic review of implementation strategies for evidence-based diagnosis of pulmonary embolism in the emergency department.

A ‘pulmonary embolism knowledge broker group’ has been formed and will meet for the first time at NCER. This group will review all of the above evidence over the course of 2018, to agree on a new process to improve the diagnosis of pulmonary embolism in the emergency department.

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