Brief Report
Imaging in the NEXUS-negative patient: when we break the rule

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Abstract

Background

In spite of general acceptance and validation of NEXUS (National Emergency X-Radiography Utilization Study) in the clearance of cervical spine (C-spine) immobilized patients, clinicians often elect to image NEXUS-negative patients in clinical practice.

Objectives

We sought to determine which variables (patient age, mechanism of injury, provider level of training, provider self-reported motivation) contribute to the decision of emergency medicine providers to image NEXUS-negative patients.

Methods

This is a prospective observational study of patients with blunt trauma and risk for C-spine injury who did not meet “trauma team activation” criteria. Providers at one high-volume emergency department (ED) prospectively recorded NEXUS criteria, as well as rationale for imaging NEXUS-negative patients. Researchers then retrospectively queried the electronic medical record for patient age, mechanism of injury, and results of diagnostic imaging. Study data were analyzed with χ2 and descriptive statistics.

Results

Three hundred patients were enrolled; 169 patients received C-spine imaging, of whom 53 were NEXUS-negative. There was no difference in imaging of NEXUS-negative patients as a factor of medical provider level of training (P = 0.42). Of NEXUS-negative patients receiving imaging, 51 (96%) were older than 65 years, and 52 were being evaluated for a fall on level ground. Imaging revealed 7 positive findings. Two of these injuries were in NEXUS-negative patients.

Conclusion

Regardless of level of training, providers in our ED often imaged patients who met NEXUS low-risk criteria. This was mot common in geriatric patients who presented after falls. This digression from NEXUS led to the diagnosis of significant injuries in 2 patients which would otherwise have been missed.

Introduction

Clinical decision rules (CDRs) are evidence based guidelines utilized by physicians to make informed decisions on when to use certain diagnostic tests and therapies while caring for patients. The NEXUS (National Emergency X-Radiography Utilization Study) cervical spine criteria are an example of one such rule that is widely used in US emergency departments (EDs), which stem from research completed in a large prospective observational study. The study, published in 2000, investigated the historically liberal use of cervical spine radiological imaging by clinicians in low risk blunt trauma patients [1]. In summary, the criteria only recommend cervical spine imaging in patients who have one or more of the following after injury: posterior midline cervical tenderness, evidence of intoxication, a focal neurological deficit, a clinically apparent painful distracting injury and decreased level of alertness. The Canadian C-spine rule (CCR) is another CDR that has been widely studied in the clearance of the cervical spine after blunt trauma [2]. The CCR is widely endorsed in Canada [3] and is viewed as an alternative triage criteria to NEXUS by the Bone and Joint Decade 2000-2010 Task Force on Neck Pain and its Associated Disorders [4]. Although there is much debate as to which rule is more accurate [5], the CCR has been reported to be relatively difficult to remember and apply as compared to other CDRs [3], [6]. A small study of US emergency physicians demonstrated increased comfort with and application of NEXUS as compared to the CCR [6]. Therefore, we chose to study application of NEXUS low-risk criteria, which is the historically preferred CDR in cervical spine clearance in our US emergency department (ED), although we acknowledge that it is unclear if it is the better rule.

The NEXUS criteria have been validated in multiple studies [7], [8], including their application to pediatric and geriatric patients [9], [10]; however, few studies have investigated their actual application in clinical practice. CDRs which have been validated often have significant barriers to their implementation [11], and anecdotally, NEXUS-negative patients are often imaged in clinical practice in spite of extensive criteria validation. To our knowledge, only one recent study has evaluated the actual use of the NEXUS rules by emergency physicians in the United States, and this study demonstrated that neither NEXUS nor the CCR were being applied well or consistently by the enrolled physicians [6]. Patient insistence to obtain imaging was the number one reason cited by physicians who did not follow the NEXUS low risk criteria, while difficulty remembering the rule was the most commonly cited reason for not using the CCR [6]. Additionally, the research found the second most common reason for digression from NEXUS was physician fear of possible medicolegal ramifications if imaging was not obtained. This study pointed out a number of clinicians who were inexperienced in using this decision rule or had difficulty remembering the criteria.

Although most academic emergency physicians and residents are aware of the NEXUS C-spine rule, our goal was to determine the prevalence of these emergency medicine (EM) providers’ adherence to the NEXUS criteria in a prospective approach. We sought to determine which patient-related variables (age, mechanism of injury) and which provider-related variables (provider level of training, provider self-reported motivation) contribute to the decision of EM residents and faculty to image patients who meet all NEXUS low-risk criteria after blunt trauma in one US ED.

Section snippets

Study design

This study was a prospective observational study of the application of NEXUS low-risk cervical spine clearance criteria by EM residents and attending physicians. The study was reviewed and approved by the hospital’s institutional review board.

Study setting and population

The study was performed at a 75,000 volume community Level 1 trauma center that hosts an EM residency training program with 40 total residents. Resident and attending physicians were educated regarding the study during mandatory education time (at weekly

Results

Three hundred patients were enrolled over an 11-month period from November 2011 to September 2012. The mean age of patients was 71 years (SD ± 22 years); 183 (61%) were women and 117 (39%) were men; 296 (99%) of patients were adults and 4 (1%) of those enrolled were children under the age of 18; 79% of patients enrolled were being evaluated after a fall; which was usually from a standing position. The remainder included 16% from motor vehicle collisions, 3% after being assaulted and 2% having

Discussion

In our cohort, the digression from applying NEXUS in this population led to the diagnosis of two injuries which would otherwise have been missed. These two injuries were in elderly patients who were ultimately managed conservatively.

After reviewing the medical record of the NEXUS negative patient suffering multiple fractures of C4, the initial clinician stated the patient was alert and oriented however a note on the chart by the attending physician reported the patient as “altered and

Limitations

Our study is limited by lack of formal follow up with patients regarding those who did not have cervical spine imaging in the ED. Although this calls into question the designation of clinically relevant injuries, we did not set out to validate the NEXUS criteria. A re-evaluation of the sensitivity and specificity of NEXUS would take thousands of patients. Granting we enrolled 300 patients and had 2 positive findings on imaging of NEXUS negative patients, 121 others were NEXUS negative and

Conclusion

Regardless of level of training, providers in our ED adhere to NEXUS criteria approximately 80% of the time. Advanced patient age, fall mechanism, and patient’s requirement for head CT led to use of cervical imaging in a significant number of NEXUS negative patients. Two of these had clinically relevant injuries which were managed conservatively. Further research is warranted regarding clinical clearance of the cervical spine in elderly fall patients who are at higher risk for injury and in

References (16)

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Presentations: American College of Emergency Medicine Denver, CO, October 2012; Society of Academic Emergency Medicine Atlanta, GA, May 2013.

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