The increased use of diagnostic imaging and especially computed tomography pulmonary angiography in patients suspected of pulmonary embolism (PE) is an important point of concerns.

The goal of this pragmatic cluster-randomized trial is to compare the diagnostic strategy based on the four-level pulmonary embolism probability score (4PEPS) and current practices.

The main questions it aims to answer is: "Does the diagnostic strategy based on 4PEPS significantly reduce the use of thoracic imaging without increasing the risk of serious adverse events as compared to current diagnostic practices?" Patients suspected of having PE in the participating emergency departments will be included and followed for 90 days. In ten centers, the emergency physicians will apply the 4PEPS strategy and in ten other centers, the emergency physicians will be free to do as they see fit. Researchers will compare the two groups of patients to see if the rate of diagnostic thoracic imaging tests and the rate of adverse events related to diagnostic strategies will differ.

Several strategies have been devised to safely limit the use of thoracic imaging in patients suspected of pulmonary embolism (PE). However, they are based on different rules for clinical probability (CP) assessment, rendering their combination difficult. The four-level pulmonary embolism probability score (4PEPS) allows the combination of all other strategies using a single CP assessment. Methods and analysis: SPEED&PEPS is a pragmatic cluster-randomized trial. After a preliminary period aimed to assess the possibility of inclusions and current practices in 23 Emergency Departments (ED), 20 EDs will be selected to participate to the active phase and randomization. Half of the centers will be allocated to the control group where physicians will be free to do as they see fit but they will be given the recommendation to apply a validated strategy. Half of the centers will be allocated to the interventional group where the physicians will be given the recommendation to apply the 4PEPS strategy. Patients with suspected PE will be included and followed for 90 days (anticipated number of patients to be included: 2560, 1280 in each arm). The primary objective will be to demonstrate that the application of the 4PEPS strategy by emergency physicians, in comparison to current practices, (i) does not increase the risk of serious events related to diagnostic strategies and (ii) significantly reduces the use of thoracic imaging. If successful, the SPEED&PEPS trial will have an important impact for patients suspected of PE limiting their irradiation and for public health in substantial savings in terms of the direct cost of diagnostic investigations and the indirect cost of hospitalizations due to waiting times or delayed harmful effects. Funding: This work is funded by a French Public Health grant (PREPS-N 2019). The funding source plays no role in the study design, data collection, analysis, interpretation or the writing of the manuscript.

Inclusion Criteria:

• Admission to an emergency department participating in the study.
• Suspected PE due to thoracic symptoms (dyspnea, chest pain, or hemoptysis) and/or syncope without any other obvious explanation after clinical examination and possible additional first-line tests (ECG, chest X-ray, or routine lab work-up).

Exclusion Criteria:

• Age < 18 years.
• Known result of a specific diagnostic imaging examination for PE (thoracic CT angiography, pulmonary scintigraphy, or venous ultrasound of the lower limbs).
• Hemodynamic instability (systolic blood pressure < 90 mmHg or more than 40 mmHg lower than usual for more than 15 min).
• Curative dose of anticoagulant in place for more than two days prior to inclusion.
• Pregnant or parturient patient.
• Patient in detention by judicial or administrative decision.
• Patient undergoing compulsory psychiatric treatment.
• Patient placed under a legal protection measure.
• Patient who objects to participating in the research (preliminary phase) or is unable to give free and informed consent (active phase).

Data will be shared upon reasonable request. Only de-identified data will be shared. Any data collected during the study may be shared. The protocol will be shared initially. Other documents may be shared at a later date upon request (e.g., the CRF to allow a collaborator to select the data they wish to access). The recipients of the data will be researchers. The data will be available for any purpose deemed relevant by the study investigator, based on a protocol provided by the requester, after verification of the obtaining of regulatory approvals, including the favorable opinion of an ethics committee.

The study protocol is already published and available (doi: 10.3390/diagnostics12123101). The data will be shared after signing a negotiated data transfer agreement ( data access agreement), for the duration specified in the agreement.

The data will be made available via secure transfer (sharing platform approved by the university hospital: BlueFiles or Oodrive).

blinded adjudication committee assessing endpoints