Clinical Decision Rules for Diagnostic Imaging in the Emergency Department: A Research Agenda

Accuracy of physician gestalt in prediction of significant abdominal and pelvic injury in adult blunt trauma patients

OBJECTIVE

Focusing on potential missed injury rates and sensitivity of low-risk of injury predictions, we sought to evaluate the accuracy of physician gestalt in predicting clinically significant injury (CSI) in the abdomen and pelvis among blunt trauma patients presenting to the emergency department (ED).

METHODS

We collected gestalt data on physicians caring for adult blunt trauma patients who received abdominal/pelvic computed tomography (CT) at three Level I and one Level II trauma centers. The primary outcome of CSI was defined as injury on abdominal/pelvic CT requiring hospitalization or intervention. Physicians evaluating trauma patients estimated the likelihood of CSI prior to abdominal/pelvic CT review (response choices: <2%, 2%-10%, 11%-20%, 21%-40%, >40%). We evaluated potential missed injury rates (prevalence of CSI) and sensitivity for prediction categories, as well as calibration and area under the receiver operating characteristic (AUROC) curve for overall physician gestalt.

RESULTS

Of 2030 patients, 402 (20%) had an injury on abdominal/pelvic CT and 270 (13%) had CSI. The <2% risk of CSI gestalt cutoff had a potential missed injury rate of 5.6% and a sensitivity of 95.2% (95% confidence interval [CI] 91.7%-97.3%). The 0%-10% cutoff of CSI gestalt had a potential missed injury rate of 6.3% (95% CI, 5.0%-7.9%) and a sensitivity of 75.2% (95% CI 69.5%-80.1%). With an overall AUROC of 0.699 (95% CI 0.679-0.719), physician gestalt was moderately accurate and calibrated for the midranges of predicted risk but poorly calibrated at the extremes.

CONCLUSIONS

Physician gestalt for the prediction of adult abdominal and pelvic CSI is moderately accurate and calibrated. However, the potential missed CSI rate and low sensitivity of the low perceived risk of injury cutoffs indicate that gestalt by itself is insufficient to direct selective abdominal/pelvic CT use in adult blunt trauma patient evaluation.

Test characteristics of ultrasound for the diagnosis of peritonsillar abscess: A systematic review and meta-analysis

BACKGROUND

Distinguishing peritonsillar abscess (PTA) from peritonsillar cellulitis using clinical assessment is challenging as many features overlap for both conditions, and physical examination is only about 75% sensitive and 50% specific for diagnosing PTA. The primary objective of this systematic review was to determine the test characteristics of ultrasound for diagnosing PTA when compared to a reference standard of computed tomography or acquisition of pus via needle aspiration or incision and drainage.

METHODS

This systematic review was performed in accordance with the Preferred Reporting Items for a Systematic Review and Meta-analysis of Diagnostic Test Accuracy (PRISMA-DTA) guidelines. We searched seven databases from 1960 to November 2022. Two independent reviewers completed study selection, data extraction, and QUADAS-2 risk-of-bias assessment. We used a bivariate random-effects model to calculate pooled sensitivity, specificity, positive likelihood ratio (LR+), and negative likelihood ratio (LR-). We also conducted subgroup analyses on radiology ultrasound compared to point-of-care ultrasound (POCUS) and intraoral compared to transcervical scanning techniques.

RESULTS

From 339 citations, we identified 18 studies for inclusion. Because one study only reported positive cases of PTA (thereby preventing the calculation of specificity), it was excluded from the analysis, so the analysis included a total of 17 studies with 812 patients, of whom 541 had PTA. Pooled bivariate sensitivity was 86% (95% confidence interval [CI] 78%-91%), specificity 76% (95% CI 67%-82%), LR+ 3.51 (95% CI 2.59-4.89), and LR- 0.19 (95% CI 0.12-0.30). On subgroup analysis, radiology-performed ultrasound had a sensitivity and specificity of 89% and 71%, compared to POCUS, which had a sensitivity and specificity of 74% and 79%. Comparing the two different techniques, intraoral had a sensitivity and specificity of 91% and 75% while transcervical had a sensitivity and specificity of 80% and 81%.

CONCLUSIONS

Ultrasound demonstrates high sensitivity for ruling out PTA, but it only has moderate specificity for ruling in the diagnosis.

Guidelines for reasonable and appropriate care in the emergency department 3 (GRACE-3): Acute dizziness and vertigo in the emergency department

This third Guideline for Reasonable and Appropriate Care in the Emergency Department (GRACE-3) from the Society for Academic Emergency Medicine is on the topic adult patients with acute dizziness and vertigo in the emergency department (ED). A multidisciplinary guideline panel applied the Grading of Recommendations Assessment, Development, and Evaluation (GRADE) approach to assess the certainty of evidence and strength of recommendations regarding five questions for adult ED patients with acute dizziness of less than 2 weeks' duration. The intended population is adults presenting to the ED with acute dizziness or vertigo. The panel derived 15 evidence-based recommendations based on the timing and triggers of the dizziness but recognizes that alternative diagnostic approaches exist, such as the STANDING protocol and nystagmus examination in combination with gait unsteadiness or the presence of vascular risk factors. As an overarching recommendation, (1) emergency clinicians should receive training in bedside physical examination techniques for patients with the acute vestibular syndrome (AVS; HINTS) and the diagnostic and therapeutic maneuvers for benign paroxysmal positional vertigo (BPPV; Dix-Hallpike test and Epley maneuver). To help distinguish central from peripheral causes in patients with the AVS, we recommend: (2) use HINTS (for clinicians trained in its use) in patients with nystagmus, (3) use finger rub to further aid in excluding stroke in patients with nystagmus, (4) use severity of gait unsteadiness in patients without nystagmus, (5) do not use brain computed tomography (CT), (6) do not use routine magnetic resonance imaging (MRI) as a first-line test if a clinician trained in HINTS is available, and (7) use MRI as a confirmatory test in patients with central or equivocal HINTS examinations. In patients with the spontaneous episodic vestibular syndrome: (8) search for symptoms or signs of cerebral ischemia, (9) do not use CT, and (10) use CT angiography or MRI angiography if there is concern for transient ischemic attack. In patients with the triggered (positional) episodic vestibular syndrome, (11) use the Dix-Hallpike test to diagnose posterior canal BPPV (pc-BPPV), (12) do not use CT, and (13) do not use MRI routinely, unless atypical clinical features are present. In patients diagnosed with vestibular neuritis, (14) consider short-term steroids as a treatment option. In patients diagnosed with pc-BPPV, (15) treat with the Epley maneuver. It is clear that as of 2023, when applied in routine practice by emergency clinicians without special training, HINTS testing is inaccurate, partly due to use in the wrong patients and partly due to issues with its interpretation. Most emergency physicians have not received training in use of HINTS. As such, it is not standard of care, either in the legal sense of that term ("what the average physician would do in similar circumstances") or in the common parlance sense ("the standard action typically used by physicians in routine practice").

Red flags Presented in Children Complaining of Headache in Paediatric Emergency Department

This study aimed to determine how common are specific red flags of life-threatening headache (LTH) among children with complaints of headache in the emergency department. A retrospective study was conducted over five years, including all patients aged < 18 years who presented for a headache to a Pediatric Emergency Department. We identified patients with life-threatening headaches and compared the recurrence of the main red flags (occipital location, vomit, nocturnal wake-up, presence of neurological signs, and family history of primary headache) to the remaining sample. Two-thousand-fifty-one children (51% female, 49% male) were included. Seven patients (0.3%) were diagnosed with a life-threatening headache. In the analysis of red flags, only the presence of abnormal neurological evaluation and vomiting was found to be more common in the LTH sample. No statistically significant difference was found for nocturnal awakening or occipital localization of pain. Urgent neuroradiological examinations were performed in 72 patients (3.5% of cases). The most common discharge diagnosis was infection-related headache (42.4%), followed by primary headaches (39.7%). This large retrospective study confirms the most recent literature suggesting that night awakenings and occipital pain are common symptoms also associated with not-LTH. Therefore, if isolated, they should not be considered red flags.

Research priority setting in emergency care: A scoping review

Objective

Priority areas for emergency care research are emerging and becoming ever more important. The objectives of this scoping review were to (1) provide a comprehensive overview of published emergency care priority‐setting studies by collating and comparing priority‐setting methodology and (2) describe the resulting research priorities identified.

Methods

The Joanna Briggs Institute methodological framework was used. Inclusion criteria were peer‐review articles available in English, published between January 1, 2008 and March 31, 2019 and used 2 or more search terms. Five databases (Scopus, AustHealth, EMBASE, CINAHL, and Ovid MEDLINE) were searched. REporting guideline for PRIority SEtting of health research (REPRISE) criteria were used to assess the quality of evidence of included articles.

Results

Forty‐five studies were included. Fourteen themes for emergency care research were considered within 3 overarching research domains: emergency populations (pediatrics, geriatrics), emergency care workforce and processes (nursing, shared decision making, general workforce, and process), and emergency care clinical areas (imaging, falls, pain management, trauma care, substance misuse, infectious diseases, mental health, cardiology, general clinical care). Variation in the reporting of research priority areas was evident. Priority areas to drive the global agenda for emergency care research are limited given the country and professional group‐specific context of existing studies.

Conclusion

This comprehensive summary of generated research priorities across emergency care provides insight into current and future research agendas. With the nature of emergency care being inherently broad, future priorities may warrant population (eg, children, geriatrics) or subspecialty (eg, trauma, toxicology, mental health) focus and be derived using a rigorous framework and patient engagement.

Diagnostic accuracy of the physical examination in emergency department patients with acute vertigo or dizziness: A systematic review and meta-analysis for GRACE-3

BACKGROUND

History and physical examination are key features to narrow the differential diagnosis of central versus peripheral causes in patients presenting with acute vertigo. We conducted a systematic review and meta-analysis of the diagnostic test accuracy of physical examination findings.

METHODS

This study involved a patient-intervention-control-outcome (PICO) question: (P) adult ED patients with vertigo/dizziness; (I) presence/absence of specific physical examination findings; and (O) central (ischemic stroke, hemorrhage, others) versus peripheral etiology. Grading of Recommendations, Assessment, Development, and Evaluations (GRADE) was assessed.

RESULTS

From 6309 titles, 460 articles were retrieved, and 43 met the inclusion criteria: general neurologic examination-five studies, 869 patients, pooled sensitivity 46.8% (95% confidence interval [CI] 32.3%-61.9%, moderate certainty) and specificity 92.8% (95% CI 75.7%-98.1%, low certainty); limb weakness/hemiparesis-four studies, 893 patients, sensitivity 11.4% (95% CI 5.1%-23.6%, high) and specificity 98.5% (95% CI 97.1%-99.2%, high); truncal/gait ataxia-10 studies, 1810 patients (increasing severity of truncal ataxia had an increasing sensitivity for central etiology, sensitivity 69.7% [43.3%-87.9%, low] and specificity 83.7% [95% CI 52.1%-96.0%, low]); dysmetria signs-four studies, 1135 patients, sensitivity 24.6% (95% CI 15.6%-36.5%, high) and specificity 97.8% (94.4%-99.2%, high); head impulse test (HIT)-17 studies, 1366 patients, sensitivity 76.8% (64.4%-85.8%, low) and specificity 89.1% (95% CI 75.8%-95.6%, moderate); spontaneous nystagmus-six studies, 621 patients, sensitivity 52.3% (29.8%-74.0%, moderate) and specificity 42.0% (95% CI 15.5%-74.1%, moderate); nystagmus type-16 studies, 1366 patients (bidirectional, vertical, direction changing, or pure torsional nystagmus are consistent with a central cause of vertigo, sensitivity 50.7% [95% CI 41.1%-60.2%, moderate] and specificity 98.5% [95% CI 91.7%-99.7%, moderate]); test of skew-15 studies, 1150 patients (skew deviation is abnormal and consistent with central etiology, sensitivity was 23.7% [95% CI 15%-35.4%, moderate] and specificity 97.6% [95% CI 96%-98.6%, moderate]); HINTS (head impulse, nystagmus, test of skew)-14 studies, 1781 patients, sensitivity 92.9% (95% CI 79.1%-97.9%, high) and specificity 83.4% (95% CI 69.6%-91.7%, moderate); and HINTS+ (HINTS with hearing component)-five studies, 342 patients, sensitivity 99.0% (95% CI 73.6%-100%, high) and specificity 84.8% (95% CI 70.1%-93.0%, high).

CONCLUSIONS

Most neurologic examination findings have low sensitivity and high specificity for a central cause in patients with acute vertigo or dizziness. In acute vestibular syndrome (monophasic, continuous, persistent dizziness), HINTS and HINTS+ have high sensitivity when performed by trained clinicians.

Developing a decision instrument to guide abdominal-pelvic imaging of blunt trauma patients: Methodology and protocol of the NEXUS abdominal-pelvic imaging study

Although computed tomography (CT) of the abdomen and pelvis (A/P) can provide crucial information for managing blunt trauma patients, liberal and indiscriminant imaging is expensive, can delay critical interventions, and unnecessarily exposes patients to ionizing radiation. Currently no definitive recommendations exist detailing which adult blunt trauma patients should receive A/P CT imaging and which patients may safely forego CT. Considerable benefit could be realized by identifying clinical criteria that reliably classify the risk of abdominal and pelvic injuries in blunt trauma patients. Patients identified as “very low risk” by such criteria would be free of significant injury, receive no benefit from imaging and therefore could be safely spared the expense and radiation exposure associated with A/P CT. The goal of this two-phase nationwide multicenter observational study is to derive and validate the use of clinical criteria to stratify the risk of injuries to the abdomen and pelvis among adult blunt trauma patients. We estimate that nation-wide implementation of a rigorously developed decision instrument could safely reduce CT imaging of adult blunt trauma patients by more than 20%, and reduce annual radiographic charges by $180 million, while simultaneously expediting trauma care and decreasing radiation exposure with its attendant risk of radiation-induced malignancy. Prior to enrollment we convened an expert panel of trauma surgeons, radiologists and emergency medicine physicians to develop a consensus definition for clinically significant abdominal and pelvic injury. In the first derivation phase of the study, we will document the presence or absence of preselected candidate criteria, as well as the presence or absence of significant abdominal or pelvic injuries in a cohort of blunt trauma victims. Using recursive partitioning, we will examine combinations of these criteria to identify an optimal “very low risk” subset that identifies injuries with a sensitivity exceeding 98%, excludes injury with a negative predictive value (NPV) greater than 98%, and retains the highest possible specificity and potential to decrease imaging. In Phase 2 of the study we will validate the performance of a decision rule based on these criteria among a new cohort of patients to ensure that the criteria retain high sensitivity, NPV and optimal specificity. Validating the sensitivity of the decision instrument with high statistical precision requires evaluations on 317 blunt trauma patients who have significant abdominal-pelvic injuries, which will in turn require evaluations on approximately 6,340 blunt trauma patients. We will estimate potential reductions in CT imaging by counting the number of abdominal-pelvic CT scans performed on “very low risk” patients. Reductions in charges and radiation exposure will be determined by respectively summing radiographic charges and lifetime decreases in radiation morbidity and mortality for all “very low risk” cases.

Trial registration: Clinicaltrials.gov trial registration number: NCT04937868.

Diagnostic accuracy of neuroimaging in emergency department patients with acute vertigo or dizziness: A systematic review and meta-analysis for the Guidelines for Reasonable and Appropriate Care in the Emergency Department

BACKGROUND

Patients presenting to the emergency department (ED) with acute vertigo or dizziness represent a diagnostic challenge. Neuroimaging has variable indications and yield. We aimed to conduct a systematic review and meta-analysis of the diagnostic test accuracy of neuroimaging for patients presenting with acute vertigo or dizziness.

METHODS

An electronic search was designed following patient-intervention-control-outcome (PICO) question, (P) adult patients with acute vertigo or dizziness presenting to the ED; (I) Neuroimaging including Computed tomography (CT), CT Angiogram (CTA), Magnetic Resonance Imaging (MRI), Magnetic Resonance Angiogram (MRA), and Ultrasound (US); (C) MRI/clinical gold standard; (O) central causes (stroke, hemorrhage, tumor, others) versus peripheral causes of symptoms. The Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines were followed. Grading of Recommendations, Assessment, Development, and Evaluations (GRADE) was used to assess certainty of evidence in pooled estimates.

RESULTS

We included studies that reported diagnostic test accuracy. Articles were assessed in duplicated. From 6,309 titles, 460 articles were retrieved, and 12 included. Non-contrast CT scan: 6 studies, 771 patients, pooled sensitivity 28.5% (95%CI 14.4-48.5%, moderate certainty) and specificity 98.9% (95%CI 93.4-99.8%, moderate certainty). MRI: 5 studies, 943 patients, sensitivity 79.8% (CI 71.4-86.2%, high certainty) and specificity 98.8% (CI 96.2-100%, high certainty). CTA: 1 study, 153 patients, sensitivity 14.3% (CI 1.8-42.8%) and specificity 97.7% (CI 93.8-99.6%). CT had higher sensitivity than CTA (21.4% and 14.3%) for central etiology. MRA: 1 study, 24 patients, sensitivity 60.0% (CI 26.2-87.8%) and specificity 92.9% (CI 66.1-99.8%). US: 3 studies, 258 patients, sensitivity ranged from 30-53.6%, specificity from 94.9-100%.

CONCLUSION

Non-contrast CT has very low sensitivity and MRI will miss approximately one in five patients with stroke if imaging is obtained early after symptom onset. Neuroimaging should not be used as the only tool for ruling out stroke and other central causes in patients with acute dizziness or vertigo presenting to the ED.

e Silva L, Bellolio F, Upadhye S, Broder JS. Repeat computed tomography in recurrent abdominal pain: An evidence synthesis for guidelines for reasonable and appropriate care in the emergency department

OBJECTIVE

Computed tomography (CT) imaging is frequently obtained for recurrent abdominal pain after a prior emergency department (ED) evaluation. We evaluate the utility of repeat CT imaging following an indeterminate index CT in low-risk abdominal pain adult ED patients.

METHODS

An electronic search was designed for the patient-intervention-control-outcome-timing (PICOT) question: (P) adult patients with low-risk, recurrent, and previously undifferentiated atraumatic abdominal pain presenting to the ED after an index-negative CT within 12 months; (I) repeat CT versus (C) no repeat CT; for (O) abdominal surgery or other invasive procedure, mortality, identification of potentially life-threatening diagnosis, and hospital and intensive care unit admission rates; and return ED visit (T), all within 30 days. Four reviewers independently selected evidence for inclusion and then synthesized the results around the most prevalent themes of repeat CT timing, diagnostic yield, ionizing radiation exposure, and predictors of repetitive imaging.

RESULTS

Although 637 articles and abstracts were identified, no direct evidence was found. Thirteen documents were synthesized as indirect evidence. None of the indirect evidence defined a low-risk subset of abdominal pain nor did investigators describe whether reimaging occurred for complaints similar to the initial ED evaluation. Included studies did not describe the index CT findings and some reported explanatory findings noted on the original CT for which repeat CTs might have been indicated. The time frame for a repeat CT ranged from hours to 1 year. The frequency of repeat CTs (2%-47%) varied across studies as did the yield of imaging to alter downstream clinical decision making (range = 5%-67%).

CONCLUSION

Due to the absence of direct evidence our scoping review is unable to provide high-quality evidence-based recommendations upon which to confidently base an imaging practice guideline. There is no evidence to support or refute performing a CT for low-risk recurrent abdominal pain.

Scenarios to improve CT head utilization in the emergency department delineated by critical results reporting

PURPOSE

Increasing use of advanced imaging in the emergency department (ED) has resulted in higher cost without better outcomes. Our goal was to evaluate the yield of CT head exams by scenario to guide efforts at improving patient selection.

METHODS

We performed a retrospective study at an academic medical center over 4 years (1/1/2014-12/31/2017). The chief complaint, imaging order, and exam result text were obtained for all adult ED encounters. For the 50 most common chief complaints leading to CT head exams, the ratio of exams to total encounters and ratio of critical results to imaging studies were calculated. Significant difference in "yield" was assessed via binomial test.

RESULTS

Over 708,145 adult ED encounters, 58,783 CT head exams were ordered, with an overall critical result yield of 8.0%. The three most common chief complaints had higher yield (p < 0.05): altered mental status (9.8%), fall (9.7%), and new headache (10.1%). Lower yield (p < 0.05) was found for 19 chief complaints: dizziness (6.2%), falls in patients > 65 years old (7.1%), syncope (5.3%), seizure with known epilepsy (4.8%), chest pain (3.7%), head injury (4.9%), headache re-evaluation (7.0%), alcohol intoxication (2.5%), fatigue (6.5%), headache-recurrent or in the setting of known migraines (5.2%), hypertension (4.4%), lethargy (5.8%), loss of consciousness (5.3%), migraine (3.2%), psychiatric evaluation (2.9%), near syncope (4.6%), drug problem (3.1%), symptomatically decreased blood sugar (3.2%), and suicidal (1.7%).

CONCLUSION

Our study provides a priority list of low yield scenarios of CT head use for improvement of patient selection.

A simple intervention to reduce your chance of missing an acute aortic dissection

INTRODUCTION

Acute aortic dissection (AAD) is a time sensitive, difficult to diagnose, aortic emergency. We sought to explore the quality of history taking in AAD and assess its impact on misdiagnosis.

METHODS

We studied a retrospective cohort of patients >18 years old who presented to two tertiary care emergency departments from January 1st 2004 - December 31st 2012 and were diagnosed with an acute aortic dissection (AAD) on CT, MRI or TEE. Trained reviewers' extracted data using a standardized data collection form. The definitions of 5 pain characteristics - character, onset, duration, quality, and radiation were defined a priori.

RESULTS

Data were collected for 194 cases of acute aortic dissection with a mean age of 65(SD 14.1) and 66.7% male, 34(17.6%) missed on initial presentation. Only 20(14.8%) patients were asked all 5 questions. The most common initial incorrect diagnosis were acute coronary syndrome (16, 47%), pulmonary embolism (5, 14.7%) and stroke (4, 11.7%). If <2 questions were asked 1 in 5 cases were missed, 4 times greater than if >2 were asked (P < 0.01).

CONCLUSION

Clinicians should ask and document the character, onset, duration, radiation and severity of pain in any patient presenting with chest, abdominal or flank pain. A focused history still remains the keystone to reducing misdiagnosis.

Imaging strategies for patients with suspicion of uncomplicated colic pain: diagnostic accuracy and management assessment

OBJECTIVE

Compare different imaging scenarios in the diagnosis of uncomplicated renal colic due to urolithiasis (URCU).

MATERIALS AND METHODS

A total of 206 prospectively included patients had been admitted with suspected URCU and had undergone abdominal plain film (APF), US and unenhanced CT after clinical STONE score evaluation. CT was the reference standard. We assessed sensitivity (Se), specificity (Spe) and Youden index for colic pain diagnosis, percentage of patients managed by urologic treatment with stone identified, percentage of alternative diagnoses (AD) and exposure to radiation, according to single imaging approaches, strategies driven by patient characteristics and conditional imaging strategies after APF and US.

RESULTS

One hundred (48.5%) patients had a final diagnosis of URCU and 19 underwent urologic treatment. The conditional strategy, i.e. CT in patients who had no stone identified at US, had a perfect sensitivity and specificity. This enabled diagnosis of all stones requiring urology management while decreasing the number of CT exams by 22%. The strategy whereby CT was used when there was neither direct or indirect APF + US finding of colic pain nor alternative diagnoses in patients with a STONE score ≥ 10 had a sensitivity of 0.95 and a specificity of 0.99, identified 84% of stones managed by urologic treatment and decreased the number of CT examinations by 76%.

CONCLUSION

In patients with clinical findings consistent with URCU, the use of ultrasound as first-line imaging modality, with CT restricted to patients with negative US and a STONE score ≥ 10, led to a sensitivity and specificity of above 95%, identified 84% of stones requiring urological management and reduced the number of CT scans needed by fourfold.

KEY POINTS

• For diagnosis, the use of APF + US as first-line imaging, with CT restricted to patients with both a normal APF + US and a STONE score ≥ 10, provides both a sensitivity and specificity superior or equal to 95% and reduces the number of CT scans necessary by fourfold. • For management, the use of APF + US as first-line imaging, with CT restricted to patients with both a normal APF + US and a STONE score ≥ 10, maintains a 84% stone identification rate in urology-treated patients.

Methodological standards for the development and evaluation of clinical prediction rules: a review of the literature

Clinical prediction rules (CPRs) that predict the absolute risk of a clinical condition or future outcome for individual patients are abundant in the medical literature; however, systematic reviews have demonstrated shortcomings in the methodological quality and reporting of prediction studies. To maximise the potential and clinical usefulness of CPRs, they must be rigorously developed and validated, and their impact on clinical practice and patient outcomes must be evaluated. This review aims to present a comprehensive overview of the stages involved in the development, validation and evaluation of CPRs, and to describe in detail the methodological standards required at each stage, illustrated with examples where appropriate. Important features of the study design, statistical analysis, modelling strategy, data collection, performance assessment, CPR presentation and reporting are discussed, in addition to other, often overlooked aspects such as the acceptability, cost-effectiveness and longer-term implementation of CPRs, and their comparison with clinical judgement. Although the development and evaluation of a robust, clinically useful CPR is anything but straightforward, adherence to the plethora of methodological standards, recommendations and frameworks at each stage will assist in the development of a rigorous CPR that has the potential to contribute usefully to clinical practice and decision-making and have a positive impact on patient care.

Clinical decision rule for non-traumatic computed tomography of the brain

OBJECTIVE

The aims of the present study were to derive and validate a clinical decision rule (CDR) to rule out the need for computed tomography of the brain (CTB) in non-traumatic patients who present to the ED.

METHODS

This is a retrospective review of non-traumatic patients who presented to the EDs in two urban hospitals and received CTB from January 2014 to December 2016. Data from one hospital were used to develop a CDR for clinically significant CTB findings. Clinically significant CTB findings were defined as acute infarction, intracranial neoplasm, intracranial haemorrhage, acute hydrocephalus, cerebral oedema and intracranial infection. Patients from another hospital were used as a validation cohort to evaluate the CDR and compare it to four previously derived CDRs.

RESULTS

There were 5296 cases in the derivation cohort, with 345 (6.5%) clinically significant CTB findings. Identified risk factors were: focal neurological deficit (adjusted odds ratio [OR] 3.4, 95% confidence interval [CI] 2.6-4.4), Glasgow Coma Scale <15 (adjusted OR 3.5, 95% CI 2.6-4.6), history of malignancy (adjusted OR 3.2, 95% CI 2.4-4.2), nausea and/or vomiting (adjusted OR 1.6, 95% CI 1.1-2.1), headache (adjusted OR 1.1, 95% CI 0.9-1.5) and coagulopathy (adjusted OR 9.2, 95% CI 2.1-41.5). These criteria and four pre-existing CDRs were applied to the validation cohort of 5098 patients from the second hospital, which had 338 (6.6%) clinically significant CTB findings. Our criteria were found to have a sensitivity of 99.7% (95% CI 99.1-100.0) and a specificity of 11.0% (95% CI 10.1-11.9). The risk of having a clinically significant CTB finding is 0.3% if patients do not meet any of the criteria.

CONCLUSION

The CDR derived in the present study achieved the highest sensitivity and a moderate specificity when compared with four other pre-existing CDRs for non-traumatic brain injury patients.

Red flag findings in children with headaches: Prevalence and association with emergency department neuroimaging

BACKGROUND

Clinicians appear to obtain emergent neuroimaging for children with headaches based on the presence of red flag findings. However, little data exists regarding the prevalence of these findings in emergency department populations, and whether the identification of red flag findings is associated with potentially unnecessary emergency department neuroimaging.

OBJECTIVES

We aimed to determine the prevalence of red flag findings and their association with neuroimaging in otherwise healthy children presenting with headaches to the emergency department. Our secondary aim was to determine the prevalence of emergent intracranial abnormalities in this population.

METHODS

A prospective cohort study of otherwise healthy children 2-17 years of age presenting to an urban pediatric emergency department with non-traumatic headaches was undertaken. Emergency department physicians completed a standardized form to document headache descriptors and characteristics, associated symptoms, and physical and neurological exam findings. Children who did not receive emergency department neuroimaging received 4-month telephone follow-up. Outcomes included emergency department neuroimaging and the presence of emergent intracranial abnormalities.

RESULTS

We enrolled 224 patients; 197 (87.9%) had at least one red flag finding on history. Several red flag findings were reported by more than a third of children, including: Headache waking from sleep (34.8%); headache present with or soon after waking (39.7%); or headaches increasing in frequency, duration and severity (40%, 33.1%, and 46.3%). Thirty-three percent of children received emergency department neuroimaging. The prevalence of emergent intracranial abnormalities was 1% (95% CI 0.1, 3.6). Abnormal neurological exam, extreme pain intensity of presenting headache, vomiting, and positional symptoms were independently associated with emergency department neuroimaging.

CONCLUSIONS

Red flag findings are common in children presenting with headaches to the emergency department. The presence of red flag findings is associated with emergency department neuroimaging, although the risk of emergent intracranial abnormalities is low. Many children with headaches may be receiving unnecessary neuroimaging due to the high prevalence of non-specific red flag findings.

North American survey on the post-neuroimaging management of children with mild head injuries

OBJECTIVEThere remains uncertainty regarding the appropriate level of care and need for repeating neuroimaging among children with mild traumatic brain injury (mTBI) complicated by intracranial injury (ICI). This study's objective was to investigate physician practice patterns and decision-making processes for these patients in order to identify knowledge gaps and highlight avenues for future investigation.METHODSThe authors surveyed residents, fellows, and attending physicians from the following pediatric specialties: emergency medicine; general surgery; neurosurgery; and critical care. Participants came from 10 institutions in the United States and an email list maintained by the Canadian Neurosurgical Society. The survey asked respondents to indicate management preferences for and experiences with children with mTBI complicated by ICI, focusing on an exemplar clinical vignette of a 7-year-old girl with a Glasgow Coma Scale score of 15 and a 5-mm subdural hematoma without midline shift after a fall down stairs.RESULTSThe response rate was 52% (n = 536). Overall, 326 (61%) respondents indicated they would recommend ICU admission for the child in the vignette. However, only 62 (12%) agreed/strongly agreed that this child was at high risk of neurological decline. Half of respondents (45%; n = 243) indicated they would order a planned follow-up CT (29%; n = 155) or MRI scan (19%; n = 102), though only 64 (12%) agreed/strongly agreed that repeat neuroimaging would influence their management. Common factors that increased the likelihood of ICU admission included presence of a focal neurological deficit (95%; n = 508 endorsed), midline shift (90%; n = 480) or an epidural hematoma (88%; n = 471). However, 42% (n = 225) indicated they would admit all children with mTBI and ICI to the ICU. Notably, 27% (n = 143) of respondents indicated they had seen one or more children with mTBI and intracranial hemorrhage demonstrate a rapid neurological decline when admitted to a general ward in the last year, and 13% (n = 71) had witnessed this outcome at least twice in the past year.CONCLUSIONSMany physicians endorse ICU admission and repeat neuroimaging for pediatric mTBI with ICI, despite uncertainty regarding the clinical utility of those decisions. These results, combined with evidence that existing practice may provide insufficient monitoring to some high-risk children, emphasize the need for validated decision tools to aid the management of these patients.

Diagnostic accuracy of the D-dimer in children

BACKGROUND

We sought to measure the diagnostic accuracy of D-dimer in children with suspected pulmonary embolism (PE).

METHODS

We queried our electronic medical record for quantitative D-dimer values obtained in all children ages 5-17 over 10 years in our 10-hospital system. Patients who had a D-dimer obtained in the evaluation of PE underwent supervised chart review to extract baseline demographics (age, sex, ethnicity), medical history, laboratory data and imaging results. PE was confirmed by imaging positive for deep vein thrombosis (DVT) or PE and excluded by imaging or no DVT or PE diagnosis within 90 days.

RESULTS

Over a 10-year period, we identified 13 792 orders for D-dimer testing in 2554 unique patients. Chart review indicated that 526 (20.6%) unique patients had D-dimer testing performed in the evaluation of PE (Cohen's kappa=0.95, 95% CI 0.85 to 1.0). Most D-dimers (465/526, 88%) were ordered in children aged >12 years. Of these 526 children, 34 (6.4%, 95% CI) had a criterion standard positive for new or recurrent PE. The mean D-dimer value was 2104±1394 ng/mL in the 34/34 PE+ children and 586±962 ng/mL in PE- children with a sensitivity of 34/34 (100%, 89% to 100%) and a specificity of 290/492 (58%, 54% to 63%). The area under the receiver operating characteristic curve was 0.90 ((0.9)87-0.94).

CONCLUSIONS

D-dimer is currently ordered in children for suspected PE in the emergency care setting, mostly in teenagers. The observed lower limit 95% CIs of 89% and 54% for diagnostic sensitivity and the specificity, respectively, suggest if used in patients with low-clinical probability, a normal D-dimer can safely exclude PE in children.

Accuracy of Computed Tomography in Diagnosis of Intra-abdominal Injuries in Stable Patients With Anterior Abdominal Stab Wounds: A Systematic Review and Meta-analysis

BACKGROUND

Workup for patients presenting to the emergency department (ED) following an anterior abdominal stab wound (AASW) has been debated since the 1960s. Experts agree that patients with peritonitis, evisceration, or hemodynamic instability should undergo immediate laparotomy (LAP); however, workup of stable, asymptomatic or nonperitoneal patients is not clearly defined.

OBJECTIVES

The objective was to evaluate the accuracy of computed tomography of abdomen and pelvis (CTAP) for diagnosis of intraabdominal injuries requiring therapeutic laparotomy (THER-LAP) in ED patients with AASW. Is a negative CT scan without a period of observation sufficient to safely discharge a hemodynamically stable, asymptomatic AASW patient?

METHODS

We searched PubMed, Embase, and Scopus from their inception until May 2017 for studies on ED patients with AASW. We defined the reference standard test as LAP for patients who were managed surgically and inpatient observation in those who were managed nonoperatively. In those who underwent LAP, THER-LAP was considered as disease positive. We used the Quality Assessment Tool for Diagnostic Accuracy Studies (QUADAS-2) to evaluate the risk of bias and assess the applicability of the included studies. We attempted to compute the pooled sensitivity, specificity, positive likelihood ratio (LR+), and negative likelihood ratio (LR-) using a random-effects model with MetaDiSc software and calculate testing and treatment thresholds for CT scan applying the Pauker and Kassirer model.

RESULTS

Seven studies were included encompassing 575 patients. The weighted prevalence of THER-LAP was 34.3% (95% confidence interval [CI] = 30.5%-38.2%). Studies had variable quality and the inclusion criteria were not uniform. The operating characteristics of CT scan were as follows: sensitivity = 50% to 100%, specificity = 39% to 97%, LR+ = 1.0 to 15.7, and LR- = 0.07 to 1.0. The high heterogeneity (I²  > 75%) of the operating characteristics of CT scan prevented pooling of the data and therefore the testing and treatment thresholds could not be estimated.

DISCUSSION

The articles revealed a high prevalence (8.7%, 95% CI = 6.1%-12.2%) of injuries requiring THER-LAP in patients with a negative CT scan and almost half (47%, 95% CI = 30%-64%) of those injuries involved the small bowel.

CONCLUSIONS

In stable AASW patients, a negative CT scan alone without an observation period is inadequate to exclude significant intraabdominal injuries.

Effectiveness of Interventions to Decrease Image Ordering for Low Back Pain Presentations in the Emergency Department: A Systematic Review

BACKGROUND

Low back pain (LBP) is an extremely frequent reason for patients to present to an emergency department (ED). Despite evidence against the utility of imaging, simple and advanced imaging (i.e., computed tomography [CT], magnetic resonance imaging) for patients with LBP has become increasingly frequent in the ED. The objective of this review was to identify and examine the effectiveness of interventions aimed at reducing image ordering in the ED for LBP patients.

METHODS

A protocol was developed a priori, following the PRISMA guidelines, and registered with PROSPERO. Six bibliographic databases (including MEDLINE, EMBASE, EBM Reviews, SCOPUS, CINAHL, and Dissertation Abstracts) and the gray literature were searched. Comparative studies assessing interventions that targeted image ordering in the ED for adult patients with LBP were eligible for inclusion. Two reviewers independently screened study eligibility and completed data extraction. Study quality was completed independently by two reviewers using the before-after quality assessment checklist, with a third-party mediator resolving any differences. Due to a limited number of studies and significant heterogeneity, only a descriptive analysis was performed.

RESULTS

The search yielded 603 unique citations of which a total of five before-after studies were included. Quality assessment identified potential biases relating to comparability between the pre- and postintervention groups, reliable assessment of outcomes, and an overall lack of information on the intervention (i.e., time point, description, intervention data collection). The type of interventions utilized included clinical decision support tools, clinical practice guidelines, a knowledge translation initiative, and multidisciplinary protocols. Overall, four studies reported a decrease in the relative percentage change in imaging in a specific image modality (22.7%-47.4%) following implementation of the interventions; however, one study reported a 35% increase in patient referrals to radiography, while another study reported a subsequent 15.4% increase in referrals to CT and myelography after implementing an intervention which reduced referrals for simple radiography.

DISCUSSION

While imaging of LBP has been identified as a key area of imaging overuse (e.g., Choosing Wisely recommendation), evidence on interventions to reduce image ordering for ED patients with LBP is sparse. There is some evidence to suggest that interventions can reduce the use of simple imaging in LBP in the ED; however, a shift in imaging modality has also been demonstrated. Additional studies employing higher-quality methods and measuring intervention fidelity are strongly recommended to further explore the potential of ED-based interventions to reduce image ordering for this patient population.

Clinical Examination for Acute Aortic Dissection: A Systematic Review and Meta-analysis

OBJECTIVES

Acute aortic dissection is a life-threatening condition due to a tear in the aortic wall. It is difficult to diagnose and if missed carries a significant mortality.

METHODS

We conducted a librarian-assisted systematic review of PubMed, MEDLINE, Embase, and the Cochrane database from 1968 to July 2016. Titles and abstracts were reviewed and data were extracted by two independent reviewers (agreement measured by kappa). Studies were combined if low clinical and statistical heterogeneity (I²  < 30%). Study quality was assessed using the QUADAS-2 tool. Bivariate random effects meta analyses using Revman 5 and SAS 9.3 were performed.

RESULTS

We identified 792 records: 60 were selected for full text review, nine studies with 2,400 participants were included (QUADAS-2 low risk of bias, κ = 0.89 [for full-text review]). Prevalence of aortic dissection ranged from 21.9% to 76.1% (mean ± SD = 39.1% ± 17.1%). The clinical findings increasing probability of aortic dissection were 1) neurologic deficit (n = 3, specificity = 95%, positive likelihood ratio [LR+] = 4.4, 95% confidence interval [CI] = 3.3-5.7, I²  = 0%) and 2) hypotension (n = 4, specificity = 95%, LR+ = 2.9 95% CI = 1.8-4.6, I²  = 42%), and decreasing probability were the absence of a widened mediastinum (n = 4, sensitivity = 76%-95%, negative likelihood ratio [LR-] = 0.14-0.60, I²  = 93%) and an American Heart Association aortic dissection detection (AHA ADD) risk score < 1 (n = 1, sensitivity = 91%, LR- = 0.22, 95% CI = 0.15-0.33).

CONCLUSIONS

Suspicion for acute aortic dissection should be raised with hypotension, pulse, or neurologic deficit. Conversely, a low AHA ADD score decreases suspicion. Clinical gestalt informed by high- and low-risk features together with an absence of an alternative diagnosis should drive investigation for acute aortic dissection.

Derivation of decision rules to predict clinically important outcomes in acute flank pain patients

OBJECTIVE

Routine CT for patients with acute flank pain has not been shown to improve patient outcomes, and it may unnecessarily expose patients to radiation and increased costs. As preliminary steps toward the development of a guideline for selective CT, we sought to determine the prevalence of clinically important outcomes in patients with acute flank pain and derive preliminary decision rules.

METHODS

We analyzed data from a randomized trial of CT vs. ultrasonography for patients with acute flank pain from 15 EDs between October 2011 and February 2013. Clinically important outcomes were defined as inpatient admission for ureteral stones and alternative diagnoses. Clinically important stones were defined as stones requiring urologic intervention. We sought to derive highly sensitive decision rules for both outcomes.

RESULTS

Of 2759 participants, 236 (8.6%) had a clinically important outcome and 143 (5.2%) had a clinically important stone. A CDR including anemia (hemoglobin <13.2g/dl), WBC count >11000/μl, age>42years, and the absence of CVAT had a sensitivity of 97.9% (95% CI 94.8-99.2%) and specificity of 18.7% (95% 17.2-20.2%) for clinically important outcome. A CDR including hydronephrosis, prior history of stone, and WBC count <8300/μl had a sensitivity of 98.6% (95% CI 94.5-99.7%) and specificity of 26.0% (95% 24.2-27.7%) for clinically important stone.

CONCLUSIONS

We determined the prevalence of clinically important outcomes in patients with acute flank pain, and derived preliminary high sensitivity CDRs that predict them. Validation of CDRs with similar test characteristics would require prospective enrollment of 2100 patients.

Emergency thoracic ultrasound and clinical risk management

PURPOSE

Thoracic ultrasound (TUS) has been proposed as an easy-option replacement for chest X-ray (CXR) in emergency diagnosis of pneumonia, pleural effusion, and pneumothorax. We investigated CXR unforeseen diagnosis, subsequently investigated by TUS, considering its usefulness in clinical risk assessment and management and also assessing the sustainability of telementoring.

PATIENTS AND METHODS

This observational report includes a period of 6 months with proactive concurrent adjunctive TUS diagnosis telementoring, which was done using freely available smartphone applications for transfer of images and movies.

RESULTS

Three hundred and seventy emergency TUS scans (excluding trauma patients) were performed and telementored. In 310 cases, no significant chest pathology was detected either by CXR, TUS, or the subsequent work-up; in 24 patients, there was full concordance between TUS and CXR (ten isolated pleural effusion; eleven pleural effusion with lung consolidations; and three lung consolidation without pleural effusion); in ten patients with lung consolidations, abnormalities identified by CXR were not detected by TUS. In 26 patients, only TUS diagnosis criteria of disease were present: in 19 patients, CXR was not diagnostic, ie, substantially negative, but TUS detected these conditions correctly, and these were later confirmed by computed tomography (CT). In seven patients, even if chest disease was identified by CXR, such diagnoses were significantly modified by ultrasound, and CT confirmed that TUS was more appropriate. The overall respective individual performances of CXR and TUS for the diagnosis of a pleural-pulmonary disease in emergency are good, with accuracy >95%.

CONCLUSION

About 20% of pneumonia cases were detectable only by CXR and 20% only by TUS and not by CXR; ie, about 40% of patients may have been misdiagnosed if, by chance, only one of the two tools had been used. The concurrent use of TUS and CXR increases the overall sensitivity and specificity. The contribution of expert telementoring and final reappraisal is a valuable and sustainable element for emergency physicians' training and performance, contributing reasonably to mitigation of clinical risks.

Predictors of Airspace Disease on Chest X-ray in Emergency Department Patients With Clinical Bronchiolitis: A Systematic Review and Meta-analysis

BACKGROUND

An abnormal chest X-ray (CXR) inconsistent with simple bronchiolitis is found in 7%-23% of cases. Despite national guidelines stating "current evidence does not support routine radiography in children with bronchiolitis"; the use of CXR in these patients remains high. Inappropriate use of CXR not only exposes children to excess radiation, but also increases medical costs. The majority of the time, CXRs are obtained to diagnose or rule out pneumonia. We aim to provide an evidence-based approach defining the utility of CXR in bronchiolitis for the diagnosis and treatment of bacterial pneumonia.

OBJECTIVES

We performed a systematic review and meta-analysis to describe potential predictors of a CXR with airspace disease in patients with bronchiolitis.

METHODS

We searched the medical literature from 1965 to June 2015 in PubMed/EMBASE using the following PICO formulation of our clinical question, "What characteristic(s) of history/physical examination (H&P) and vital signs (VS) in a child with bronchiolitis should prompt the physician to order a CXR?": Patients-pediatric emergency department (ED) patients (<2 years) with clinical bronchiolitis; Intervention-H&P and VS; Comparator-a CXR positive for airspace disease (+CXR), defined as atelectasis versus infiltrate or infiltrate/consolidation; and Outcome-operating characteristics of H&P and VS predicting an +CXR were calculated: sensitivity, specificity, and likelihood ratios (LR+ or LR-). The methodologic quality of the studies was assessed using the quality assessment of studies of diagnostic accuracy tool (QUADAS-2). We created a test-treatment threshold model based on the operating characteristics of the CXR to accurately identify a child with bronchiolitis and a superimposed bacterial pneumonia while accounting for the risks of a CXR and risks of treating patients with and without a bacterial infection.

RESULTS

We found five studies including 1,139 patients meeting our inclusion/exclusion criteria. Prevalence of a +CXR ranged from 7% to 23%. An oxygen saturation < 95% was the predictor with highest LR+ of 2.3 (95% confidence interval = 1.3 to 3.07) to predict a +CXR. None of the H&P and VS variables were found to have sufficiently low LR- to significantly decrease the pretest probability of finding a +CXR. Our test-treatment threshold model showed that hypoxia (O₂ Sat < 95%) alone complicating bronchiolitis did not show a benefit to obtaining a CXR. Our model only suggested that a CXR maybe indicated for a child with hypoxia (O₂ Sat < 95%) and respiratory failure requiring ventilatory support.

CONCLUSION

No single predictor of a +CXR was of sufficient accuracy to either support or refute ordering a CXR in a child with clinical bronchiolitis. We provide a decision threshold model to estimate a test threshold for obtaining a CXR and a treatment threshold for administering antibiotics. Application of this model requires the clinician to approximate the empiric benefit of antibiotics based on the clinical situation, highlighting the importance of clinical assessment.

Comparison of Prediction Rules and Clinician Suspicion for Identifying Children With Clinically Important Brain Injuries After Blunt Head Trauma

OBJECTIVE

Children with minor head trauma frequently present to emergency departments (EDs). Identifying those with traumatic brain injuries (TBIs) can be difficult, and it is unknown whether clinical prediction rules outperform clinician suspicion. Our primary objective was to compare the test characteristics of the Pediatric Emergency Care Applied Research Network (PECARN) TBI prediction rules to clinician suspicion for identifying children with clinically important TBIs (ciTBIs) after minor blunt head trauma. Our secondary objective was to determine the reasons for obtaining computed tomography (CT) scans when clinical suspicion of ciTBI was low.

METHODS

This was a planned secondary analysis of a previously conducted observational cohort study conducted in PECARN to derive and validate clinical prediction rules for ciTBI among children with minor blunt head trauma in 25 PECARN EDs. Clinicians recorded their suspicion of ciTBI before CT as <1, 1-5, 6-10, 11-50, or >50%. We defined ciTBI as 1) death from TBI, 2) neurosurgery, 3) intubation for more than 24 hours for TBI, or 4) hospital admission of 2 nights or more associated with TBI on CT. To avoid overfitting of the prediction rules, we performed comparisons of the prediction rules and clinician suspicion on the validation group only. On the validation group, we compared the test accuracies of clinician suspicion > 1% versus having at least one predictor in the PECARN TBI age-specific prediction rules for identifying children with ciTBIs (one rule for children <2 years [preverbal], the other rule for children >2 years [verbal]).

RESULTS

In the parent study, we enrolled 8,627 children to validate the prediction rules, after enrolling 33,785 children to derive the prediction rules. In the validation group, clinician suspicion of ciTBI was recorded in 8,496/8,627 (98.5%) patients, and 87 (1.0%) had ciTBIs. CT scans were obtained in 2,857 (33.6%) patients in the validation group for whom clinician suspicion of ciTBI was recorded, including 2,099/7,688 (27.3%) of those with clinician suspicion of ciTBI of <1% and 758/808 (93.8%) of those with clinician suspicion >1%. The PECARN prediction rules were significantly more sensitive than clinician suspicion >1% of ciTBI for preverbal (100% [95% confidence interval {CI} = 86.3% to 100%] vs. 60.0% [95% CI = 38.7% to 78.9%]) and verbal children (96.8% [95% CI = 88.8% to 99.6%] vs. 64.5% [95% CI = 51.3% to 76.3%]). Prediction rule specificity, however, was lower than clinician suspicion >1% for preverbal children (53.6% [95% CI = 51.5% to 55.7%] vs. 92.4% [95% CI = 91.2% to 93.5%]) and verbal children (58.2% [95% CI = 56.9% to 59.4%] vs. 90.6% [95% CI = 89.8% to 91.3%]). Of the 7,688 patients in the validation group with clinician suspicion recorded as <1%, CTs were nevertheless obtained in 2,099 (27.3%). Three of 16 (18.8%) patients undergoing neurosurgery had clinician suspicion of ciTBI <1%.

CONCLUSIONS

The PECARN TBI prediction rules had substantially greater sensitivity, but lower specificity, than clinician suspicion of ciTBI for children with minor blunt head trauma. Because CT ordering did not follow clinician suspicion of <1%, these prediction rules can augment clinician judgment and help obviate CT ordering for children at very low risk of ciTBI.

Developing a Research Agenda to Optimize Diagnostic Imaging in the Emergency Department: An Executive Summary of the 2015 Academic Emergency Medicine Consensus Conference

The 2015 Academic Emergency Medicine (AEM) consensus conference, "Diagnostic Imaging in the Emergency Department: A Research Agenda to Optimize Utilization," was held on May 12, 2015, with the goal of developing a high-priority research agenda on which to base future research. The specific aims of the conference were to: 1) understand the current state of evidence regarding emergency department (ED) diagnostic imaging utilization and identify key opportunities, limitations, and gaps in knowledge; 2) develop a consensus-driven research agenda emphasizing priorities and opportunities for research in ED diagnostic imaging; and 3) explore specific funding mechanisms available to facilitate research in ED diagnostic imaging. Over a 2-year period, the executive committee and other experts in the field convened regularly to identify specific areas in need of future research. Six content areas within emergency diagnostic imaging were identified prior to the conference and served as the breakout groups on which consensus was achieved: clinical decision rules; use of administrative data; patient-centered outcomes research; training, education, and competency; knowledge translation and barriers to imaging optimization; and comparative effectiveness research in alternatives to traditional computed tomography use. The executive committee invited key stakeholders to assist with planning and to participate in the consensus conference to generate a multidisciplinary agenda. There were 164 individuals involved in the conference spanning various specialties, including emergency medicine (EM), radiology, surgery, medical physics, and the decision sciences. This issue of AEM is dedicated to the proceedings of the 16th annual AEM consensus conference as well as original research related to emergency diagnostic imaging.