a b s t r a c t

Background: Emergency departments (ED) are sites of prevalent imaging overuse; however, determinants that drive imaging in this setting are not well-characterized. We systematically reviewed the literature to summarize the determinants of imaging overuse in the ED. Methods: We searched MEDLINE(R) and Embase(R) from January 1998 to March 2017. Studies were included if they were written in English, contained original data, pertained to a U.S. population, and identified a determinant as- sociated with overuse of imaging in the ED. Results: Twenty relevant studies were included. Fourteen evaluated Computerized tomography scanning in patents presenting to a regional ED who were then transferred to a level 1 trauma center; incomplete transfer of data and poor Image quality were the most frequently described reasons for repeat scanning. Unnecessary pre- transfer scanning or repeated scanning after transfer, in multiple studies, was highest among older patients, those with higher injury severity scores (ISS) and those being transferred further. Six studies explored determi- nants of overused imaging in the ED in varied conditions, with overuse greater in older patients and those having more comorbid diseases. Defensive imaging reportedly influenced physician behavior. Less integration of ser- vices across the health system also predisposed to overuse of imaging.

Conclusions: The literature is heterogeneous with surprisingly few studies of determinants of imaging in Minor head injury or of spine imaging. Older patient age and higher ISS were the most consistently associated with ED imaging overuse. This review highlights the need for precise definitions of overuse of imaging in the ED.

(C) 2017

healthcare expenditures in the United States remain exceptionally high, without consistent Health benefits [1,2]. The disparity between costs and outcomes of care has received much attention [3] and suggests that Healthcare services are overused in the US [4]. Within the emergency department (ED), radiologic imaging is recognized as a healthcare service that is overused. Indeed, use of imaging in the ED has increased dispro- portionate to the number of visits in recent decades. Kocher and col- leagues reported that ED visits increased nationwide by 30% from 1996 to 2007 while Computed tomography scanning (CT) rose 330% [5]. Data from the National Hospital Ambulatory Medical Care Survey further

support this trend; use of CT or magnetic resonance imaging (MRI) tri- pling and use of ultrasound doubled between 2001 and 2010 [6].

Reduction of unnecessary imaging in the ED has been an area of sig- nificant focus recently. In 2013 and 2014, as partners in the choosing wisely campaign led by the American Board of Internal Medicine (ABIM) Foundation, the American College of Emergency Physicians (ACEP) released guidelines that cautioned against low-yield imaging for a number of clinical conditions [7]. In 2015, the Society for Academic Emergency Medicine (SAEM) held a consensus conference focused on a research agenda to optimize diagnostic imaging in the ED [8].

? We acknowledge the funding support from K24 AG049036-01A1 from National Institute on Aging (J.S., R.S.); U1QHP28710 from Health Resource and Services Administration (S.N.); 2016 MSTAR Summer Scholar from American Federation for Research Training (J.P.); Johns Hopkins University Dean’s Fund (M.T.). This work was presented at the Lown Institute Conference in May 2017 in Boston, MA. All authors have no conflicts of interest.

* Corresponding author at: 624 N. Broadway Room 644, Baltimore, MD 21205, United States.

E-mail address: [email protected] (J.B. Segal).

¹ Presently.

https://doi.org/10.1016/j.ajem.2017.10.049

0735-6757/(C) 2017

While there is growing appreciation that overuse of services is prevalent in our healthcare system including in the ED, the determinants of overuse are poorly characterized [9]. In this systematic review, we focus specifically on summarizing determinants of imaging overuse in the ED. We aimed to systematically synthesize the primary literature describing factors that are positively or negatively associated with overuse of imaging in this setting.

Methods

For this review, overuse was operationally defined in accordance with the definition used by the Agency for Healthcare Research and Quality as “the provision of health care services where the likelihood of harm exceeds the likelihood of benefit.” [10] Because the term over- use was seldom employed by the original study authors, we needed to deduce whether imaging overuse was being described. We determined by consensus that studies describing duplicate imaging, imaging in con- tradiction to established guidelines, and imaging that was determined by the authors of the included studies to be unnecessary or inappropri- ate with valid justification (see Table 1) were relevant to this review.

Data sources and searches

We began with a scoping review by searching MEDLINE(R) and Embase(R) from January 1998 through July 2016. Our initial search broadly included terms reflecting use and overuse of healthcare services, including procedures and Diagnostic tests. We searched using the medical subject heading terms and keywords related to the overuse of healthcare services: “medical over- use” OR “health services misuse” OR health services overutilization OR “un- necessary procedures” OR medically unnecessary procedures OR Diagnostic Tests, Routine/utilization OR Defensive Medicine OR Practice Patterns OR Health Services Abuse OR Health Services Overuse OR medical overutiliza- tion OR inappropriate utilization. We followed with a targeted search through March 1, 2017 with specific terms for articles addressing overuse of imaging in the ED: “diagnostic imaging” OR radiography OR tomography OR scanning OR scans OR scan OR imaging OR “magnetic resonance” OR “di- agnostic testing” OR “diagnostic evaluation.” We hand searched the refer- ence lists of each included article as well as related systematic reviews for additional articles. Searches were limited to human studies in the English language. Our protocol followed PRISMA guidelines and was registered in Prospero (#CRD42015029482) as part of a broader review examining over- use of several types of healthcare services.

Study selection

Two reviewers independently screened titles, abstracts, and full-text for inclusion. Differences between reviewers were resolved through consensus adjudication. Studies were included if they were written in English, contained original data, pertained to a U.S. population, and identified a determinant associated with overuse of imaging in this set- ting. Studies describing only the prevalence of overuse, and not its de- terminants, were excluded. We further restricted the study to data collected after 1996, given the substantial changes in the U.S. healthcare system in the past two decades regarding availability of imaging tech- nologies. We had no restrictions regarding study design.

Data extraction, quality, and applicability assessment

Using standardized forms, reviewers extracted information on the gen- eral study characteristics, study participant characteristics, the methods of data collection, the overuse event under investigation, the determinants evaluated by the investigators and the determinants identified as being significantly associated with the overuse event. The determinants were classified as being related to the patient, the clinician, or the environment including the region and health system. A second reviewer confirmed the accuracy of the abstracted data. We used the criteria for determining statis- tical significance as had been defined by each article. For studies that

analyzed significance with both bivariate and multivariate methods, we extracted only the significant results from the multivariate analyses.

Two reviewers independently assessed the risk of bias in included arti- cles using previously validated instruments. The Critical Appraisal Checklist (from the Center for Evidence Based Management) was used for cohort studies and surveys [11]. The single qualitative study was assessed using the Checklist for Qualitative Research from the Joanna Briggs Institute [12].

Data synthesis and analysis

We created detailed evidence tables. We synthesized the results by the type of imaging and then by the determinants, organized as patient- level, clinician-level, and organizational or environmental. We created summary tables of these results. The results were not amenable to quan- titative pooling given the heterogeneity in design across studies.

Role of the funding source

The funders had no role in this project.

Results

We identified 10,859 titles meeting our inclusion criteria. Of these, 484 articles proceeded to full-text review (Appendix Fig. 1). We identi- fied 20 studies meeting our inclusion criteria that examined determi- nants of overuse of imaging in EDs.

Characteristics of included studies

The included studies were five retrospective cohort studies [13-17], two cross-sectional studies [18,19], six surveys [20-25], four prospective cohort studies [26-29], two studies having both retrospective and pro- spective cohort components [30,31], and one qualitative study [32].

Determinants were evaluated for their independent contribution to over- use with multivariate regression methods in seven of the studies [15-17, 27-30]. Five studies reported only bivariate analyses [13,14,18,25,26], and seven were entirely descriptive in their presentation of results [19-24,31].

Because the majority of identified studies focused on duplicate imaging in transferred trauma patients, we present the results as: 1) determinants of duplicate imaging in patients with trauma transferred to a trauma cen- ter, and 2) determinants of unnecessary, inappropriate or defensive imag- ing in the ED among diverse patients who were not transferred.

Risk of bias

This body of literature was not of high quality. The risk of bias was determined to be moderate in 13 studies [13-16,18,20,21,23-25,27,28, 30] and high in four studies [19,22,26,31]. Only two studies [17,29] were considered to have a low risk of bias. Prominent flaws included the lack of reporting of response rates in surveys and the lack of use of validated tools for data collection. Most of the studies did not clearly describe the characteristics of the study participants at enrollment. The quality of the single qualitative study was good [32].

Determinants of duplicated scans in Transferred patients with trauma

Twelve studies described scans duplicated in patients arriving at a level 1 trauma center after transfer [13-16,19,22-24,26,28,29,31]. Two studies de- scribed acquisition of scans at the referring facility prior to emergent transfer [17,25].

Eight out of 12 studies of duplicate scans upon arrival probed the rea- sons for ordering the duplicated scan; this was learned either by survey [22], by medical record review [13,19,26,29,31] or by medical record review with adjunctive physician report [23,24] (Table 2). Two reasons were noted in all eight studies: 1) the scan was not received by the trauma center or there was inadequate transfer of data; and 2) the quality of the transferred

Table 1

Study characteristics of included studies.

Author, year study design

Data site Data source Years of collection

Affected patient population Overuse event

Duplicated scans in transferred patients with trauma

Moore, 2013 [25]

mixed – prospective cohort and survey

Rural, academic medical center in Vermont

Medical record review and interviews of physicians caring for 39 patients

2009-2010 Transferred patients with trauma Duplicate CT scan within 24 h

from initial scan

Liepert, 2014 [29] prospective cohort Bible, 2014 [16]

retrospective cohort

2 academic medical centers in Utah

Academic medical center in Tennessee

Prospective data collection 2009-2010 Patients with trauma transferred

to a level 1 trauma center Medical record review 2009-2013 Adults with trauma transferred to

a level 1 trauma center

Duplicate CT scan by receiving hospital

Repeat imaging defined as the same imaging modality performed on the same spine region at the receiving hospital

Cook, 2010 [22]

Cross sectional study

Academic medical center in North Carolina

Comprehensive patient registry in the hospital’s trauma program

2002-2007 Children with blunt trauma

transferred to level 1 trauma center

Repeated abdominal CT scan

Gupta, 2010 [34]

mixed – retrospective (cross-sectional) and prospective cohort Haley, 2009 [31]

prospective cohort

Jones, 2012 [32]

prospective cohort

Rural, academic medical center in New Hampshire

Urban, level 1 tertiary care trauma center in Phoenix, Arizona

Level 1 trauma center in Morgantown, West Virginia

Trauma registry 2006-2008 Patients with trauma transferred to a level 1 trauma center

Medical records 2006-2006 Patients with trauma transferred to a level 1 trauma center

Medical record review 2010-2010 Patients with trauma transferred

to a level 1 trauma center

Repeated CT imaging at receiving center

Repeated imaging at receiving center

Repeated CT imaging at receiving center

Sung, 2009 [26]

prospective cohort and survey

Level 1 trauma academic medical center in Boston, Massachusetts

Medical record review and survey of ordering physicians

2007-2008 Patients transferred to a level 1

trauma center

Repeat CT imaging at receiving center

Farach, 2015 [17] retrospective cohort

Pediatric trauma center in St. Petersburg, FL

Pediatric trauma registry 2001-2012 All transferred pediatric patients Repeat CT of the head, chest,

and/or abdomen and pelvis within 24 h of transfer

Emick, 2011 [18]

retrospective cohort

Young, 2011 [19]

retrospective cohort

Liepert, 2011 [27] prospective cohort and survey

Two academic, level 1 trauma centers in North Carolina

Level 1 trauma center in Richmond, Virginia

Regional adult level 1 trauma center in Utah serving 4 states

State trauma registry and medical records

Trauma registry and medical records

Medical records and survey of ordering physician

2004-2008 Patients with trauma transferred to a level 1 trauma center

2005-2010 Adult patients with trauma

transferred to a level 1 trauma center

2009-2010 Adult patients with trauma

transferred to a level 1 trauma center

Repeat CT imaging of chest and/or abdomen

Repeat CT scans at receiving center

Repeat CT scans at receiving center

Lee, 2008 [28]

survey

Mohan, 2010 [20]

retrospective cohort

Level 1 trauma center at Lexington, Kentucky

Level 1 trauma center in Western Pennsylvania serving 5 states

Survey of referring physicians 2005-2006 Patients with trauma transferred

to a level 1 trauma center

Trauma registry 2000-2007 Patients with trauma transferred to a level 1 trauma center

Expectation of ordering imaging in a patient that will be transferred

Pretransfer CT scan in patients who will be immediately transferred due to trauma severity

Unnecessary, inappropriate or defensive imaging in non-transferred patients in the emergency department

Parma, 2014 [21]

cross sectional

Benarroch-Gampel, 2011 [33]

mixed – retrospective and prospective cohort

Community teaching hospital in Pennsylvania

Academic medical center in Texas

Trauma registry 2010-2012 Adult with trauma and Glasgow Coma Score of 15

Medical record review 2005-2010 Patients with acute gallbladder

disease

CT in patients with no visible head injury, loss of consciousness, amnesia, or neurologic complaint Abdominal CT in evaluation of acute Gallbladder disease

Waxman, 2000 [30] prospective Cohort

Community hospital in California

Direct observation of patients by research assistants

1997-1998 Patients with non-traumatic

abdominal or chest pain who are non-English speakers and have a language-discordant doctor

Abdominal CT and abdominal radiographs

Chen, 2015 [23]

mixed – prospective cohort and survey

One city in Utah In-person survey of physicians 2012-2012 Trauma system activation patients

presenting at a level 1 trauma center

Self-reported defensive scanning: physicians were asked, in a litigation free environment, which scans would and would not be ordered?

Kanzaria, 2015 [24] cross sectional – survey only

Medical conferences attended by academic and community-based clinicians

In-person survey of 435 physicians 2013-2013 Patients of survey respondents

(emergency physicians)

Self-report: perception by survey respondents that CT or MRI ordered by themselves and their colleagues was unnecessary

Melnick, 2015 [35] qualitative

Academic level 1 trauma center in New Haven, Connecticut

FoCUS groups, cognitive task analysis (direct observation), critical decision method (interviews)

2013-2014 Adult patients presenting to the ED with diagnosis of concussion, head injury or minor traumatic brain injury

Head CT for minor head injury in the ED

CT = Computed tomography imaging, MRI = magnetic resonance imaging.

image was inadequate for clinical care [13,19,22-24,26,29,31]. Other rea- sons for duplication of imaging included physician preference for repeat imaging [24,26,31], the belief that repeating a scan in a transferred patient was routine care [19], and a consultant’s request or convenience [29].

Patient factors

Six of the 12 studies of duplicate imaging upon arrival analyzed pa- tient factors associated with receipt of a repeated scan [13-16,28,29]. One of the two studies of inappropriate imaging prior to transfer also examined patient factors [17]. All seven of these were cohort studies.

Six studies tested the association with age, with half finding significant as- sociations: two reported that imaging was more likely to be performed on middle age or older patients, with the mean ages of 42.3 years [16] and over 65 years [17]. One reported higher rates of repeat imaging in the youn- gest children (mean age 6.3 years) [14]. Four studies tested whether repeat imaging depended on the patient’s sex [14,16,17,29]. Three did not find sig- nificant associations; the one that did reported that inappropriate imaging prior to transfer was more likely to occur in women than men [17]. Race was only analyzed in a single study and was not influential [16].

Six studies tested associations with Injury Severity Score (ISS) with all

finding that imaging was associated with higher ISS scores [14-17,28,29]. One cohort study looked at medically stable versus unstable transferred pa- tients with spine injuries [13]. Medically unstable patients were less likely to have their imaging sent and viewable to the receiving institution, and yet were not significantly more likely to have repeat imaging. The cohort study by Mohan et al. also reported that medically unstable patients were less likely to receive imaging prior to transfer than their stable counterparts [17]. Mech- anism of injury was a significant determinant of repeat imaging in two [14, 17] of the six studies that evaluated this [14-17,28,29].

Insurance status was a significant factor in just one [17] of three studies [15,17,29]. In multivariate analysis of 7713 adults presenting to a non-trau- ma center with indications for immediate transfer to a trauma center, pa- tients with Medicare received more duplicate CT scans while Uninsured patients had fewer duplicate CT scans, when compared to patients with Commercial insurance [17]. Emick et al. did not find a significant association between repeated scanning in 1375 trauma patients who had received a scan prior to transfer and their insurance status [15]. Jones et al. also did not see a significant association between insurance and repeated CT scans in a multivariate analysis involving 211 patients [29].

Physician factors

The only physician-level factor, Advanced Trauma Life Support certifica- tion, was examined in a cohort study [17] and a physician survey [25]. Both studies found that physicians with Advanced Trauma Life Support certifica- tion were neither more nor less likely to order imaging than physicians with- out [17,25].

Environmental and systemic factors

Five cohort studies analyzed the environmental or system level fac- tors contributing to repeat imaging [13-15,17,26]. Two studies analyzed the impact of distance from the receiving trauma center; a greater dis- tance was associated with CT scanning upon arrival [14] and with scan- ning prior to transfer [17]. The latter study also evaluated the impact of the volume of trauma patients at the referring institution and found this was not significantly associated with scanning prior to transfer [17].

The cohort study by Emick et al. found that transport by helicopter

was associated with greater likelihood of scanning upon arrival com- pared to transport by ground, after thorough adjustment for variables characterizing the patient and the facilities [15].

Liepert et al. compared rates of repeated CT scanning after transfer in an integrated health system (where the referring hospital and trauma hospital are part of the same system with fully integrated medical records and radi- ology picture archiving) versus a more conventional health system [26]. The integrated health system had a significantly lower proportion of repeat imaging. In another study, transferred patients with spine injury were

significantly more likely to have a CT upon arrival if the original CT scan was not viewable at the receiving institution [13].

Determinants of unnecessary, inappropriate or defensive imaging in non-transferred patients in the emergency department

Six studies evaluated determinants of overused imaging in the ED with overuse defined as unnecessary, inappropriate or defensive imag- ing [18,20,21,27,30,32].

Patient factors

One cross-sectional study [18], two cohort studies [27,30], and one qualitative study [32] evaluated patient factors contributing to unneces- sary or inappropriate imaging in the ED (Table 3).

The cross-sectional study, of patients with mild head injury, reported only unadjusted results, finding that middle aged patients (41-64 years) were more likely to receive unnecessary head CT compared to younger (18-40 years) and older (65+ years) patients [18]. Additionally, receipt of unnecessary head CT was associated with patient’s illicit drug use, vehic- ular injury as compared to fall or assault or other injury mechanism, and an ISS N 26 compared to ISS between 15 and 25. Neither patients’ sex nor alco- hol use was significantly associated with head CT overuse.

In a multivariate analysis of patients presenting to the ED with com-

plicated gallstone disease, wherein authors considered ultrasonography to be the appropriate diagnostic test, older age predicted inappropriate use of abdominal CT [30]. Other significant associations in the multivar- iate model were the presence of hypertension, elevated white blood count, and abnormal amylase on laboratory analyses [30]. Patient sex, race, Previous ED visit, and other laboratory values and comorbidities were not significant predictors of receipt of abdominal CT [30].

A prospective cohort study reported that non-English speaking patients

experienced a higher rate of abdominal CT for abdominal pain than did En- glish language speakers. This relationship was not found for other diagnos- tic imaging tests, specifically Abdominal radiographs (plain film) for abdominal pain, chest radiographs or echocardiography for chest pain [27]. A qualitative study by Melnick et al. used patient and physician focus groups, cognitive task analysis after direct observation in the ED, and in- terviews with four senior physicians to identify themes related to inap- propriate receipt of CT for a minor head injury. Patient-level themes that were identified included patients’ expectations of receiving of CT, pa- tients’ lack of tolerance for ambiguity (as perceived by the physician),

and patients’ balance of short and long term risks [32].

Clinician factors

One cohort study [30], one cross sectional [21] and one qualitative study

[32] evaluated clinician factors associated with unnecessary or inappropri- ate imaging in the ED (Table 3). The cohort study, described above, of pa- tients with complicated gallstone disease, found that the time of placement of the order for imaging by clinicians was the single largest pre- dictor of inappropriate CT use, with inappropriate CT orders much more likely in the evening than daytime; weekend or weekday ordering of imag- ing did not predict inappropriate CT use [30]. Similarly, the admitting service to which the patient was directed did not drive CT use in this situation.

In the cross-sectional survey of ED providers’ perceptions of inap- propriate imaging in their department, most respondents reported that they believed the main contributor to overuse was fear of missing a low-probability diagnosis and avoidance of malpractice issues [21]. The less strongly endorsed responses were: perception of patient or family expectations, imaging as standard practice in their medical groups or among their closest colleagues, imaging as standard practice in emergency medicine, that the test saves time, administrative pres- sures to increase group reimbursement, and increased personal reimbursement. Respondents who chose to write in a reason for overuse mentioned that imaging was often done at the request of a non-ED physician [21].

Table 2

Determinants of duplicate scans in transferred patients with trauma.?

Author, year

N, overuse events

Patient determinants Clinician

determinants

System and environmental determinants

Liepert, 2014 [26]

480 trauma patients w/ 144 repeated CT

Bible, 2014 [13]

1427 trauma patients with spine injuries w/ 194 repeated CT, radiograph or MRI

NE NE Non-integrated health system

(48% of patients) vs integrated health system (16% of patients) p = 0.0001

Medically stable or unstable NE Unsent CT (50%) vs. sent (23%) CT from outside hospital p = 0.0001

Haley, 2009 [28]

410 trauma patients w/ 218 repeated CT Jones, 2012 [29]

211 trauma patients w/ 82 repeated CT Farach, 2015 [14]

8658 pediatric patients w/ 288 repeated CT

Emick, 2011 [15]

1375 adult patients w/ 820 repeated CT

Young, 2011 [16]

2678 adult patients w/ 559 repeated CT

Higher ISS (6% increase odds of overuse for each point, p = 0.002), age, injury mechanism, length of stay at transferring facility

Higher ISS (for every unit increase in ISS, odds increase 3.6% [p = 0.0361]), injury mechanism, Insurance type, sex, age

Younger age (more overuse-repeated CT scan vs no repeated

CT scan [mean: 6.3 vs 7.2 years, p b 0.01]), higher ISS (more overuse – repeated CT scan vs no repeated CT scan [mean: 12.2 vs. 8.7, p b 0.01]), GCS 13 or 14 (less overuse — repeated CT scan vs no repeated

CT scan [mean: 13.1 vs. 14.1, p b 0.01]), motorized trauma/penetrating trauma/assault vs fall/nonmotorized trauma/sports

related injury [p b 0.05], sex

ISS between 24 and 33 relative to ISS b 15

(more overuse [OR, 1.6; 95% CI, 1.05-2.4]), triage

alert criteria 1, 2, relative to 3 (more overuse

[OR, 1.6; 95% CI, 1.01-2.7 for level II; OR, 2.2; 95% CI,

1.2-4.1 for level I]), age, arrival SBP, arrival GCS, mechanism of injury (motor vehicle collision or other), insurance status

Higher ISS (for every point increase, OR, 1.02; 95% CI, 1.01-1.03; p = 0.0001), older age (for every year increase, OR 1.006; CI, 1.003-1.010; p = 0.0004), race, injury mechanism, sex

NE NE

NE NE

NE Greater hospital distance

(more overuse [repeated CT scan vs

no repeated CT scan [mean: 69vs.

49.2 miles, p b 0.01]])

NE Helicopter versus ground transport

(more overuse [OR, 1.6; 95% CI, 1.2-2.2]), referring center volume, day of transfer, year of admission

NE NE

Lee, 2008 [25]

survey of 143 physicians

NE ATLS NE

certification

Mohan, 2010 [17]

N = 7713

4434 patients w/3303 having repeated CT

Female (more overuse [OR, 1.18; 95% CI, 1.05-1.33]), older age (more overuse [OR, 1.30; 95% CI, 1.07-1.58 if age 65-80 yrs.; OR, 2.19; 95% CI,

1.79-2.77 if age N 80]),

obesity (less overuse [OR, 0.56; 95% CI, 0.41-0.78]), Medicare

(more overuse [OR, 1.44; 95% CI, 1.18-1.74]) and uninsured

(less overuse [OR, 0.66; 95% CI, 0.57-0.76]) relative to commercially-insured,

Motorcycle collision (less overuse [OR 0.81, 95% CI 0.68-0.97]

or penetrating injury (less overuse [OR, 0.16; 95% CI, 0.11-0.20])) relative to motor vehicle accident, lower ISS (more overuse

[OR, 1.66; 95%CI, 1.43-1.91 if ISS 16-23; OR, 1.59; 95% CI, 1.32-1.92 if ISS 24-33])

ATLS

certification

Greater distance from hospital (more overuse), volume of trauma patients

ATLS = Advanced Trauma Life Support, CT = computed tomography scan, GCS = Glasgow Coma Score, ISS = Injury Severity Score, MRI = magnetic resonance imaging, NE = not ex- amined, PGY = postgraduate year, SBP = systolic blood pressure.

* Statistically significant determinants of overuse are in bold, the direction of effect is in parentheses.

Multiple clinician-level themes emerged from the qualitative study by Melnick et al. on inappropriate head CT for minor head injury [32]. The most frequently reported themes were about establishing trust as a way to minimize inappropriate head CT use: this included attending to Patient engagement, providing reassurance, caring for the patient as a person, identifying and addressing patient concerns, identifying and managing patient anxiety and tolerance for uncertainty. Other fac- tors included clinicians’ confidence and experience, their anxiety and their tendencies toward risk aversion.

Systemic and Environmental factors

The cohort study of gallstone evaluation [30] and two surveys [20, 21] evaluated health system or environmental factors contributing to unnecessary or inappropriate imaging in the ED. The cohort study, by Benarroch-Gampel, noted the absence of a trend in inappropriate CT use from 2005 to 2009 in evaluation of acute cholecystitis [30]. Kanzaria et al. reported from their survey of ED providers that more respondents outside of California endorsed ordering medically unnecessary CTs or magnetic resonance images (MRIs) than respondents in California and more in non-group-based HMOs than in group-based HMOs [21]. When attending trauma surgeons were surveyed about whether they would practice similarly to their current practice in a litigation-free

environment, they responded that the litigious environment in which they practiced was a major driver of their imaging orders [20].

Discussion

In this systematic review, we synthesized the primary literature de- scribing determinants that are positively or negatively associated with overuse of imaging in the ED. Fourteen (70%) of the included studies ad- dressed overuse of CT scans in trauma patients presenting to a local ED with subsequent transfer to a level 1 trauma center. The authors of the primary studies considered this practice to be overuse because it gener- ates little new information, harms patients with radiation or discomfort, delays treatment and increases the Costs of care. Determinants associat- ed with receipt of a duplicate scan include those representing clinical instability–patients at the extremes of age and/or more severely in- jured (Table 4). One might argue that these are not all episodes of over- use in these clinically unstable patients; but, for this review, we used the definition of overuse provided in each of the included articles.

Other findings suggest that there may be systematic biases regard-

ing who gets more imaging, such as determined by insurance status. Others identified determinants included environmental factors like dis- tance between hospitals and whether the referring and receiving

Table 3

Determinants of unnecessary, inappropriate or defensive imaging in non-transferred patients in the emergency department.?

Author, year

unnecessary imaging event: count (when available)

Patient determinants Clinician determinants System and environmental determinants

Parma, 2014 [18]

head CT for minor trauma in absence of head injury, loss of consciousness, amnesia, or neurologic complaint: 106 of 438 adult patients

More CT overuse among patients 41 to 64 years, or with drug use, or vehicular

injury, or surgery within 24 h (p b 0.05) –

only univariate analyses

NE NE

Benarroch-Gampel, 2011 [30] Abdominal CT for acute gallbladder disease: 234 of 562 patients

Older age, per 5-year increase (OR, 1.14; 95% CI 1.07-1.21); elevated white blood

cell count (OR, 1.67; 95% CI, 1.10-2.53);

elevated amylase (OR, 2.02; 95% CI,

1.16-3.51); hypertension (OR, 2.01; 95% CI, 1.20-3.37) sex, race, previous ED visit, diagnosis (acute cholecystitis v. gallstone pancreatitis v. common bile duct stones)

Imaging in the evening (relative to daytime) (OR, 4.44; 95% CI, 2.88-6.85),

weekend imaging, admitting service

Year of event from 2005 to 2009

Waxman, 2000 [27]

N = 324

172 English speaking and 152 non-English speaking patients with nontraumatic chest pain or abdominal pain

non-English language relative to English speakers (more overuse of abdominal CT for pain – mean difference in proportions 10.9%, 95% CI 1.0% to 20.8%)

NE NE

Kanzaria, 2015 [21] CT or MRIs

N = 435

NE Main perceived contributor of overuse: fear of missing a low-probability diagnosis

and avoidance of Malpractice litigation; other contributory factors: patient or family expectations, standard practice in medical group, standard practice in ED, the test saves time, administrative pressure to increase reimbursement, increase in personal reimbursement

Most frequent “write-in comment” was request of non-ED physician to perform testing.

Greater perception of self-ordering of medically unnecessary imaging in

non-California vs. California (26% vs 20% overuse), non-group based HMO vs. group-based HMO (25% vs. 18%)

Chen, 2015 [20]

1097 CT scans were performed on 295 Trauma activation patients litigation vs. litigation free environment

NE NE Litigious environment (more overuse) relative to practice influenced only by clinical judgment

Melnick, 2015 [32] focus groups of patients

(four groups, 22 subjects total) and providers (three groups, 22 subjects total)

inappropriate head CT in mild head injury

Patient expectations (expects a CT), anxiety, patient engagement

Establishing trust/bedside manner (patient engagement, reassurance, listening and caring for patient as a person, identifying and addressing concerns, provider confidence/experience, ability to identify and manage patient anxiety and tolerance for uncertainty), anxiety (risk aversion), constraints (time, concussion knowledge gap), influence of other providers (PCP, consultant, resident, mid-level)

CT = computed tomography scan, ED = emergency department, ISS = Injury Severity Score, PCP = primary care physician.

* Statistically significant determinants of overuse are in bold; direction of effect is in parentheses.

hospitals were part of an integrated system where there is more seam- less transfer of records and imaging files.

The remaining six studies were more varied in the types of imaging

that were studied. Indeed, while three studies used guideline-deter- mined definitions of non-indicated CT scans for mild head injuries and acute gallbladder disease, the remaining three used vaguer definitions like physicians’ self-perception about unnecessary imaging or testing. Like in the repeated testing studies, overuse was greater in patients who were older or who had more comorbid disease.

Other determinants, like time of day, suggest that overuse is related to staffing deficiencies (such as lack of ultrasonography technicians at night) or crowding of the ED, but this was not explicitly examined. This is supported by the qualitative study, which suggested that overuse of head CT would be reduced by engaging patients and managing pa- tient expectations and anxiety–practices that necessitate greater time at the bedside. Defensive medicine as a driver of overuse, including im- aging, has been previously described and was noted by physicians as influencing their behavior. Finally, as with the repeated CT scan studies,

less health system-level integration also predisposed to imaging over- use in the ED (Table 5).

To our knowledge, there are no other systematic reviews on this topic. There are many studies that describe variation in use of imaging without probing the determinants of this variation and without explor- ing whether the variation represents overuse or underuse. Levine and colleagues studied ED physicians at a single level 1 trauma center and found rates of ordering of imaging varied across physicians three-fold [33]. Marin and colleagues, using the Nationwide Emergency Depart- ment Sample, found 40% variation in CT use for children with head trau- ma across EDs, with differences between academic and non-academic medical centers [34]. Patient race and insurance type influence the diag- nostic workup received by patients in the ED, but it is unclear, again, whether this represents underuse or overuse of services [35,36]. Other studies have also demonstrated more intensive health service utiliza- tion, besides imaging, in the ED for patients who speak languages other than English, possibly in an effort to overcome diagnostic chal- lenges posed by communication difficulties [37,38].

Table 4

Summary of determinants associated with duplicate scans in transferred patients with trauma.

Factors

(number of studies)

Determinants examined

Studies reporting significance/studies evaluating the association

Key findings

Patient factor (6 studies)

System and environmental determinants

(5 studies)

Age 3/6 Younger age was associated in 1 study and older age in 2 studies.

Sex 1/4 Female sex was associated in 1 study.

ISS score 6/6 Higher ISS scores were associated in 6 studies.

Insurance status 1/3 Insurance status was associated in 1 study.

Mechanism of injury 2/6 Mechanism of injury was associated in 2 studies.

Health system 1/1 Non-integrated health system was associated in 1 study compared integrated health system.

Scan sent outside 1/1 Whether the outside hospital had sent the scan to the receiving hospital, (unsent CT) was associated in 1 study.

Distance 2/2 A greater distance was associated in 2 studies.

transport mode 1/1 Transport by helicopter was associated in 1 study compared to transport by ground.

Limitations and strengths

Our review has several limitations. First, a limitation is the varying defini- tions of overuse across the studies. Second, some may argue that repeating scans in transferred patients is frequently appropriate (and not overuse) due to a clinical status change and this may not have been easily captured in the studies that used administrative data. Third, the studies examining utilization in the ED (non-transferred patients) used a variety of definitions and yet many of the determinants were consistent across studies. Fourth, our search strategy focused on terms related to “overuse” and may have missed articles focused on guideline-discordant care, although additional hand searching did not identify other relevant articles. Fifth, we did not search for gray litera- ture so publication bias is a possibility; that is, analyses of wasteful services may be conducted within health systems and not published, such as when there are null findings or findings that reflect poorly on the health system. However, we expect that our exclusion of unpublished literature would not importantly change our conclusions given that our synthesis was entirely qualitative and missing a single study would not change point estimates and confidence intervals as it might in a quantitative synthesis of study results.

We note that the quality of the included studies was only fair; only two of

the included studies were deemed to have a low risk of bias. Additionally, the response rates in the surveys were often not reported and might be presumed to have been low. It is hard to know in which direction this biased the results. We recognize that many of the studies described factors associated with over- use that may not in fact be causal determinants; the methods used in the primary studies methods do not permit definitive comments about causality.

Study strengths include our use of a second reviewer, which minimizes

the likelihood of incorrect extraction of data about determinants. Additionally,

our inclusion of surveys in the review allowed for the association between de- terminants and perceptions of determinants of overuse to be included.

Future research

As high resolution radiologic imaging becomes more widespread in hospitals, there will be an even greater need for understanding its value to pa- tients. The ABIM, Academy Health, the Robert Wood Johnson Foundation and the Agency for Healthcare Research and Quality have all recognized the harmful impact of overuse on patient health and health systems. A research agenda set forth by Morgan et al., emphasized gaps in our understanding of determinants, including their relative importance, interaction and the potential value of chang- ing any one determinant in isolation [39]. These authors wonder in particular about the role of communication, clinical uncertainty and cognitive biases ascon- tributors to overuse. Additional research is needed that explores a wider breadth of determinants and their modifiers, preferably using a consistent definition of overuse. Studies that can quantify the impact of determinants on overuse will further enable evidence-based policies to be implemented and evaluated.

Several of the common determinants of repeated imaging–scans not sent with the patient, incomplete transfer of data, poor quality of scans, lack of health system integration–can be improved with standardization of protocols and improved technological interoperability between refer- ring and receiving sites. As health information exchanges (HIE) gain functionality [40,41], there should be more opportunity to avoid dupli- cation of scans ordered because of incomplete transfer of data.

Targeting physician ordering behaviors has been a core strategy in mul- tiple interventions designed to reduce inappropriate imaging in hospitals. Decision support systems often use existing infrastructure of the electronic

Table 5

Summary of determinants associated with unnecessary, inappropriate or defensive imaging in non-transferred patients in the emergency department.

Categories (number of studies)

Determinants examined Studies reporting

significance/studies evaluating the association

Key findings

Patient factors (4 studies)

Age 2/2 Middle age was associated in 1 study and older age was in other study.

Drug use 1/1 Drug use was associated in 1 study.

Mechanism of injury 1/1 Mechanism of injury was associated in 1 study.

Laboratory values and comorbidities

1/1 Presence of hypertension, elevated white blood count, and abnormal amylase on laboratory analyses were associated in 1 study.

Clinician factors

Language 1/1 language barrier was associated in 1 study.

ISS score 1/1 Higher ISS scores was associated in 1 study.

Patient-level themes 1/1 Patient expectations (expects a CT), anxiety, patient engagement were associated in 1 study. Time of imaging 1/1 Imaging in the evening was associated in 1 study.

3 studies

Factors believed to contribute most to unnecessary imaging

1/1 Main contributor was fear of missing a low-probability diagnosis and avoidance of potential malpractice suits. Frequent “write-in comment” was request of non-ED physician to perform testing was associated in 1 study.

Clinician-level themes 1/1 Establishing trust/bedside manner was associated in 1 study.

System and environmental

Practice location, practice type, reimbursement method

1/1 Self-ordering of medically unnecessary CT/MRIs in non-California states than in California and in non-group based HMOs than in group-based HMO were associated in 1 study.

(3 studies) Litigious environment 1/1 Current litigious environment was perceived to be a major driver of imaging orders in 1 study.

CT = computed tomography scan, ED = emergency department, ISS = Injury Severity Score, PCP = primary care physician.

medical record; ordering physicians may receive a “low-value” message if they order a test that may be considered inappropriate based on the patient’s characteristics [42]. Multifaceted approaches are likely to be more impactful than reliance on messaging alone; the literature strongly supports “alert-fatigue” that lessens the impact of many messaging systems [43,44]. Promisingly, overuse of imaging in the ED has been addressed by several societies contributing recommendations to the Choosing Wisely Initiative. This national campaign, initiated by the ABIM Foundation and supported by the American College of Physicians, promotes conversations between cli- nicians and patients to help them choose care that is “supported by evidence, not duplicative of other tests or procedures already received, free from harm and truly necessary” [45]. The ACEP cautions to avoid CT scans of the head in patients with minor head injury not meeting criteria for imaging by validat- ed decision rules, and to avoid CT of the abdomen and pelvis in young pa- tients in the ED with known Kidney stones and symptoms of renal colic. The College recommends avoidance of lumbar spine imaging in the ED for adults with non-traumatic back pain and no red-flag symptoms, avoidance of CT pulmonary angiography in patients with a low likelihood of pulmonary embolism, and avoidance of CT of the head in asymptomatic adult Patients with syncope or minor trauma and a normal neurological

evaluation.

Conclusion

Overuse of ED imaging is common yet there is little consistency in the de- terminants described across studies of this topic. The wide range of determi- nants identified in these studies represent avenues for future research and then intervention. This review highlights the need for more precise defini- tions of overuse of imaging tests in the ED, and more thorough investigation of factors driving overuse in this setting.

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