VALIDATION OF CLINICAL DECISION AIDS FOR MIDFACIAL AND MANDIBULAR INJURY,
THE REDUCTION V TRIAL, A prospective multicentre cohort trial.

Currently, computed tomography (CT) is considered the gold standard for the
diagnosis of midfacial and mandibular fractures. The easy availability of the
CT scan has led to an exponential increase in the number of CT examinations for
patients with suspected midfacial and mandibular fractures. This in turn has
led to an increase in the cost and radiation exposure within this population of
patients. In both midfacial and mandibular fractures, specific clinical
parameters have shown to be contributing but not decisive in ruling out
fractures. Testing for a set of these specific clinical parameters, for
example, in a decision aid, could be of aid in deciding to preform imaging
and/or predict the required treatment. Thus, a decision aid for stratifying
midfacial and mandibular injury could reduce the number unnecessary imaging in
patients with midfacial and mandibular injuries and thereby reduce costs and
radiation exposure. For this reason, the REDUCTION study group was established
as a multidisciplinary collaboration between the emergency medicine, radiology,
trauma surgery and oral and maxillofacial surgery departments to reduce
unnecessary imaging, and resulted in the REDUCTION I and II studies (Approval
METc 2017/249), In these studies, four decision aids have been developed based
on clinical parameters, in order to rule out: I) the presence of midfacial
fractures, II) the presence of midfacial fractures that require active
treatment, III) the presence of mandibular fractures, and IV) the presence of
mandibular fractures that require active treatment. Initial analysis showed a
proportional reduction of 5-15% in maxillofacial CT scans for maxillofacial
injuries in the ED. However, the external validity of these clinical decision
aids needs to be established before they can be incorporated into routine
clinical practice.

The primary objective of this study is to validate the clinical decision aids
developed in the REDUCTION I & II studies for patients with midfacial and/or
mandibular injury in the emergency department.

Prospective multicenter cohort study

Each patient with a midfacial and/or mandibular injury will receive a
standardised physical examination based on the REDUCTION I and II clinical
decision aids. The midfacial and/or mandibular clinical decision aids are used
to predict the presence of midfacial and/or mandibular fractures and the
presence of midfacial and/or mandibular fractures requiring active treatment.
After physical examination in the emergency department (ED), patients are
scanned with either a maxillofacial CT or low-dose cone beam computed
tomography (CBCT). Later, the choice of treatment for a maxillofacial fracture,
active or conservative (standard of care), will be reviewed by chart review.

This study cohort will contain two subgroups.

The first subgroup will include patients who have a regular clinical indication
for maxillofacial CT in the ED as part of standard care. Patients in this
subgroup will not be exposed to additional radiation. These are patients with
midfacial or mandibular injuries with a high clinical suspicion of a midfacial
or mandibular fracture. For this subgroup, the entire study is standard of
care. In the previous REDUCTION I study, maxillofacial CT was performed in 80%
of patients with mandibular injury and 85% of patients with midfacial injury
presenting to the ED.

The second subgroup will include patients who do not receive a maxillofacial CT
scan in the ED as part of standard care because of a low clinical suspicion of
fracture.

An estimate of the percentage of patients in this subgroup can be made based on
the REDUCTION I study. In this study, maxillofacial CT was not performed in
20% of patients with mandibular injuries and 15% of patients with midfacial
injuries because the suspicion of a maxillofacial fracture was low.

Given the endpoint of this study, i.e. absolute certainty of the presence or
absence of a maxillofacial fracture, all patients with midfacial or mandibular
injuries will need to undergo maxillofacial imaging. For validation, it would
be best to screen all patients with the gold standard, a maxillofacial CT scan.
However, taking into account the ALARA (as low as reasonably achievable)
principle in imaging to minimise radiation dose to patients, CBCT is more
appropriate.

The second subgroup of patients will be asked to visit the outpatient clinic of
oral, maxillofacial and maxillofacial surgery within a week. During this visit,
patients will undergo a physical examination of the midface and/or mandible by
an oral surgeon, followed by CBCT scanning of the affected area. CBCT scans are
considered to have a significantly lower radiation dose than CT scans.
Nevertheless, they have been shown to be more than sufficient for diagnosing
maxillofacial fractures, even at very low doses. The UMCG uses a value of 0.07
millisieverts for maxillofacial CBCT, compared with doses of 0.4 millisieverts
for a CT. For the second subgroup, CBCT is not part of standard care and is
therefore considered an additional burden. However, the advantage of the
additional CBCT for this subgroup of patients is that it ensures that fractures
of the midface and/or mandible are not missed .