Pediatr Radiol (2008) 38 (Suppl 4):S664–S669 DOI 10.1007/s00247-008-0892-z

ALARA: BUILDING BRIDGES BETWEEN RADIOLOGY AND EMERGENCY MEDICINE

CT utilization: the emergency department perspective Joshua Seth Broder

Received: 25 January 2008 / Accepted: 23 April 2008 / Published online: 23 September 2008 # Springer-Verlag 2008

Abstract CT scan utilization in the pediatric emergency department (ED) has dramatically increased in recent years. This likely reflects the improved diagnostic capability of CT, as well as its wider availability. However, the utility of CT is tempered by the high radiation exposure to patients as well as cost. In this review we will consider the magnitude of changes in CT use in the pediatric ED, and we will examine some of the driving forces behind these increases. In addition, we will consider strategies to limit growth in CT scan utilization or even result in reductions in CT use in the future. These strategies include better physician and patient education, application of existing clinical decision rules to reduce CT utilization and development of new rules, technical alterations in CT protocols to reduce perexam exposures, use of alternative imaging modalities such as US and MRI that do not expose patients to ionizing radiation, and expanded use of clinical observation in place of immediate diagnostic imaging. Reform of liability laws might alleviate another driving force behind high CT utilization rates. Protocols must be designed to maximize patient safety by limiting radiation exposures while preserving rapid and accurate diagnosis of time-sensitive conditions.

Introduction Background and scope CT scan utilization in the pediatric emergency department (ED) has dramatically increased in recent years. This likely reflects the improved diagnostic capability of CT, as well as its wider availability. However, the utility of CT is tempered by the high radiation exposure to patients as well as cost concerns. In this review we will consider the magnitude of changes in CT use in the emergency department, and we will examine some of the driving forces behind these increases. In addition, we will consider strategies to limit growth in CT scan utilization or even result in reductions in CT use in the future. These strategies need to be designed to maximize patient safety by limiting radiation exposures while preserving rapid and accurate diagnosis of time-sensitive conditions.

Discussion Recent trends in utilization of CT in the pediatric emergency department

Keywords CT utilization . Radiation . Emergency . Pediatric

Dr. Broder has no relevant financial relationships or potential conflicts of interest related to the material to be presented. J. S. Broder (*) Division of Emergency Medicine, Duke University Medical Center, P.O. Box 3096, Durham, NC 27713, USA e-mail: [email protected]

Although detailed national figures for the emergency department setting are not available, a study of CT scan utilization in the pediatric emergency department (ED) of a single tertiary care university center between 2000 and 2006 revealed dramatic increases [1]. During this time frame, the pediatric ED population increased by only 2%, with little change in the severity of illness as assessed by triage acuity scores, which are validated measures of the need for immediate patient assessment and treatment, correlated to likelihood of admission or ICU stay [2–5].

Pediatr Radiol (2008) 38 (Suppl 4):S664–S669 Table 1 Percentage increase in CT utilization in the ED 2000– 2006 by patient age.

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Type of CT

Percent increase, patient age 0–2 years

Percent increase, patient age 3–12 years

Percent increase, patient age 13–17 years

Percent increase, patient age ≥18 years

2 180 100 −31 50

8 175 283 41 34

62 731 675 72 217

66 557 309 104 280

Head Cervical spine Chest Abdomen Miscellaneous

From Broder et al. [1], copyright 2007, reprinted with permission from Springer-Link.

Despite this, CT of the head, cervical spine, chest, abdomen, and other body regions all increased at high rates, far exceeding changes in ED volume or acuity. As shown in Table 1 and Figs. 1 and 2, CT utilization in all age groups from the youngest children through adolescence increased at rates between 30% and 400%—meaning that CT utilization outpaced ED volume growth by 15- to 200fold during this period. An exception to this growth was abdominal CT use in the 0- to 2-year-old age group, where utilization fell by approximately 30%. Head CT in this youngest age group occurred at a rate closely matching growth in ED volume, but these are exceptions to the overall trend. Growth in CT utilization was greatest in adolescence [1], perhaps reflecting the fact that as children appear more adult-like, physicians adopt strategies used in the evaluation of adult patients. These strategies include the growing practice of pan-CT (CT of the head, cervical spine, chest, abdomen, and pelvis) for trauma evaluation, sometimes with little stratification of imaging utilization based on patient physical exam or complaints [6]; immediate use of CT for evaluation of abdominal pain, rather than use of clinical observation; and CT scanning prior to specialty

consultation, rather than at the request of a consultant following his or her examination of the patient (for example, CT of the abdomen in the evaluation of appendicitis, prior to surgical consultation). Why this intense use of CT in adults and adult-like adolescents? In part, emergency physicians might be unaware that radiation sensitivity and potential cancer risk persist into adulthood, declining toward an “adult plateau” at approximately age 35 years, according to work by Brenner [7]—so emergency physicians might see little impetus to restrict CT use except in the youngest patients. In addition, emergency physicians might anticipate the diagnostic requests of consultants and order imaging prior to consultation in an effort to expedite care. Below, a variety of other factors potentially promoting increased CT utilization will be discussed. Driving forces in utilization, and possible solutions The complex and multi-factorial problem of increasing CT utilization in the pediatric ED will be solved only by adoption of a multi-pronged and multi-disciplinary approach, requiring the cooperation of emergency physicians, radiologists, and other specialists involved in the care of

5% 435% 366%

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cervical spine

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miscellaneous

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Fig. 1 Increase in CT utilization by CT type, compared with pediatric emergency department (ED) volume. From Broder et al. [1], copyright 2007, reprinted with permission from Springer-Link

head

cervical spine

chest

abdomen

miscellaneous

Fig. 2 Percentage of pediatric emergency department (ED) evaluations involving CT. From Broder et al. [1], copyright 2007, reprinted with permission from Springer-Link

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pediatric ED patients. The first step in this solution will be education about potential radiation dangers. The diagnostic capability of CT is clear, and emergency physicians are trained to be cautious and accurate in their diagnoses. Without an awareness of harms from CT, emergency physicians have readily adopted CT into their practice. A survey published in 2004 indicated that at that time, only about 9% of emergency physicians and 47% of radiologists were aware of any radiation risk from CT—and given this level of physician ignorance, it should come as no surprise that only 3% of patients were aware of any danger [8]. Since that time, the risks of radiation have risen to the attention of physicians and patients. A report in the New England Journal of Medicine in November 2007 implicated radiation exposures from CT scanning in as many as 2% of U.S. cancers [9]—and the study was immediately echoed in Newsweek magazine online [10], as well as all major television news networks. Although passive penetration of information on radiation risk into the ranks of physicians and patients might be occurring, an active education campaign to provide both groups with an accurate understanding of the true radiation risks of CT is needed. It would be inappropriate for physician and patient impressions to be driven by reports in the popular press, which might exaggerate the true risk from a single exam. In addition, the immediate risk to the patient from potential acute pathology must be weighed against the delayed risk from any diagnostic radiation exposure, and physicians can only perform this complex calculation when armed with accurate risk data for CT. Education needs to be directed not only at emergency physicians and patients, but also at consultants in a broad array of specialties, including general pediatricians. Patient safety is not improved if CT scans are deferred by emergency physicians, only to be ordered immediately upon admission to the hospital or at the request of consulting physicians prior to evaluation of ED patients. Studies show that CT is increasingly utilized in the assessment of abdominal conditions. From 1999 to 2004, CT use in adult patients diagnosed with appendicitis increased from 51% to 76% in one study [11], while in children with appendicitis, CT utilization increased from 1.3% to 58% from 1997 to 2001 [12]. Substantial education might be needed to reverse a decade of increasing reliance on diagnostic imaging for clinical decision-making. However, education about radiation risks is not the complete answer. Although some CT scans might be ordered without a strong indication and without consideration of radiation exposure, many are ordered because a reasonable concern for an acute, dangerous medical condition exists. Knowledge of the dangers of a radiation exposure might increase the anxiety of the patient and the ordering physician, but understanding the radiation risk does not alleviate the

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danger of a potential emergency condition and thus might not reduce CT utilization, unless viable alternatives to immediate CT imaging exist. Emergency physicians need tools to facilitate their selection of patients for immediate CT scan or observation. For patients who are overtly well, CT or other diagnostic imaging might not be needed—again, awareness of radiation risk is essential among physicians to prevent the practice of “checking just to be sure” despite a very low pretest probability. An entire branch of emergency medicine research has developed around clinical decision rules, which are criteria used to limit use of expensive or invasive testing, and which are composed of readily available clinical data such as physical exam findings and elements of the patient history [13]. Well-known examples such as NEXUS, the Canadian cervical spine rule, the Ottawa foot and ankle rule, Canadian head CT rule, and Ottawa and Pittsburgh knee rules accurately identify patients with very low probability of disease and have the ability to reduce use of radiography by up to 40–50%, but these rules are relatively rarely employed by physicians [13, 14]. One barrier to use of clinical decision rules is apparent complexity of application, while physicians are more likely to express willingness to apply a rule if they are exposed during training and if they perceive it to be an efficient use of time [15]. Physicians often employ elements in clinical decision-making that have specifically been found to offer no additional discriminatory diagnostic value, and they often fail to remember all elements of well-validated rules [16]—problems easily solved in theory with memory aids such as PDAs or pocket cards. More research and effort is needed to ensure utilization of well-validated decision rules. As more emergency departments move to electronic physician order entry, clinical decision rules could be incorporated as mandatory fields for test ordering, ensuring implementation. Coupled with a renewed awareness of the risk of radiation, these rules can be reinforced as a safe and legally protective means of documenting adequate patient evaluation. For the overtly sick patient, a viable alternative to diagnostic imaging with CT might be empiric therapy without imaging, for example appendectomy in the patient with classic findings of appendicitis. CT in this instance of overt diagnosis might have little value, and radiation risk might exceed benefit. Enhancing the understanding of radiation risks among both emergency physicians and specialists such as surgeons is necessary if this path is to be pursued. Objective tools to characterize patients who do not require CT, including clinical scoring systems such as the Alvarado score (Table 2) for appendicitis [17, 18], can play a role in identifying patients who do not require imaging at this extreme of the spectrum of illness. In one recent retrospective study of patients 7 years and older, an

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Table 2 The Alvarado scoring system for appendicitis. Mnemonic (MANTRELS) Symptoms

Signs

Laboratory Total score

Migration Anorexia-acetone Nausea-vomiting Tenderness in RLQ Rebound pain Elevation of temperature >37.3°C Leukocytosis Shift to the left

Value 1 1 1 2 1 1 2 1 10

Scores >7 are moderately specific for appendicitis. From McKay and Shepherd [17], copyright 2007, reprinted with permission from Elsevier.

Alvarado score of 7 or higher was 100% specific for the diagnosis of appendicitis, and the authors concluded that patients with scores in this range should undergo surgical consultation rather than CT [17]. Prospective validation of rules such as these that identify high-risk patients not requiring imaging, specifically in a pediatric population, could reduce CT utilization in patients with overt disease. A prospectively derived and validated clinical decision rule to identify pediatric patients at low risk of appendicitis has also been published and is predicted to reduce CT utilization by as much as 20% in patients at the lower end of the spectrum of illness [18]. Unfortunately, clinical decision rules have been developed for only a tiny fraction of clinical scenarios—head, neck, and lower extremity trauma, for example, so much work remains to expand these tools to the vast array of patient presentations in the emergency department. In addition, relatively little work has been done in the development of clinical decision rules in children [18, 19]. In fact, many of the existing well-validated decision rules explicitly excluded children in their development or enrolled relatively few patients in the youngest age groups [20, 21], leaving emergency physicians with few validated methods for identifying those patients who require diagnostic imaging. In the absence of evidence, emergency physicians must rely on their individual assessment and gestalt. In addition to clinical decision rules based on historical and exam findings, laboratory biomarkers of specific injuries are currently under investigation and might help to limit utilization of diagnostic imaging. An example in the adult population is the D-dimer, which in conjunction with low-risk clinical criteria such as the Well’s criteria for pulmonary embolism can be used to exclude thromboembolic disease without imaging [22]. Unfortunately, biomarker tests are often poor surrogates, as they are subject to false-positive results and might prompt increased use of

diagnostic imaging when improperly applied to very lowrisk populations. In children, biomarkers such as C-reactive protein have long been investigated for a variety of conditions but have not found widespread clinical utility because of poor receiver–operator curve characteristics for many conditions. A recent study suggests that elevated levels differentiate complicated from simple appendicitis [23]. Combinations of biomarkers have also been proposed but fall prey to similar limitations of unacceptable sensitivity and specificity [24]. For patients with equivocal presentations, some form of further evaluation is necessary. The time-honored methods of observation and serial examinations deserve renewed attention. The alternatives to immediate CT include discharge to home with observation by family, observation in the ED, diagnostic imaging using modalities that do not expose the patient to ionizing radiation, and admission to the hospital for observation. Currently, discharge to home is an unrealistic option for many patients who have refractory symptoms such as pain or nausea, for patients who have an unstable social situation, and for those in whom clinical deterioration might rapidly occur before return to the ED could be arranged. These patients cannot be observed for prolonged periods in the ED because ED crowding is at a record level nationally, as highlighted in numerous reports including those by the Institute of Medicine [25–27]. In addition, more than 90% of pediatric patients are seen in general emergency departments, so issues of ED crowding directly impact the ability of emergency physicians to observe children for extended periods in the ED [26]. Currently, patients are often refused admission to the hospital without a specific diagnosis, as U.S. inpatient beds have declined in number since the 1980s, from 1.36 million hospital beds in 6,933 hospitals in 1981 to 829,000 beds in 4,950 hospitals in 1999. U.S. hospital-based EDs have also declined in number, from 4,547 in 1994 to 4,177 in 1999—leaving fewer EDs to evaluate, treat, and observe patients [28]. Increasing crowding and boarding of ED patients has been linked to increased mortality—so prolonged observation of children in an ED setting might be detrimental for these patients and others in the ED [29]. Bound by these constraints, emergency physicians feel enormous pressure to make a rapid diagnosis to facilitate disposition—and diagnostic imaging with CT is a common pathway. The emergency physician is therefore at an impasse unless diagnostic information can be obtained or inpatient beds can be increased to allow observation of patients. Even in the recent past, CT scanning has been seen as a safe and economically beneficial strategy because it allows many ED patients to be discharged home [30, 31], but in the future observation might be a better choice for long-term patient outcomes by avoiding radiation exposures. It might be better to pay for observation now rather than to spend

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money on diagnostic imaging resulting in delayed patient morbidity and mortality from radiation-induced cancers. Much work has been done recently by the radiology community to reduce radiation exposure per CT exam. These strategies include reduction of mAs and peak tube kilovoltage based on patient mass [32–34]. A trend to the lowest acceptable image resolution that preserves diagnostic capability is underway and promises reductions in radiation exposure of perhaps 40–50%. Ingenious strategies such as reduced radiation CT for follow-up of known lesions and for repeated CT scans (for example in children with hydrocephalus who frequently undergo CT for evaluation of ventriculomegaly) are part of the solution. Another potential strategy is limited CT scan, for example CT scan only of the lower abdomen and pelvis in patients in whom appendicitis is the only strongly suspected diagnosis [35, 36]. These strategies, while essential, might pale in comparison to the dramatic increases in the number of exams ordered [37]. Radiologists also need to be wary of recommendations for CT imaging following screening plain films or CT. An increasing number of plain film interpretations are accompanied by the phrase “CT is recommended if clinically indicated.” Such cautious statements might prompt unnecessary CT exams. One danger of the widening use of CT scanning is that a new generation of radiology residents might be relatively unfamiliar with, and consequently uncomfortable with, reading plain films as “normal.” Thirty percent of CT examinations performed are at a radiologist’s recommendation [38]. In one ED study, 31% of abdominal CT reports recommended a second imaging study [39]. Nearly 40% of follow-up abdominal CTs recommended by radiologists do not provide additional useful information [40]. Referring physicians place a relatively low value on the recommendations of radiologists for additional imaging [41] but might be compelled for medical–legal reasons to perform recommended exams. An additional strategy is the replacement of CT scanning with modalities that do not expose the patient to ionizing radiation. In many settings, US is seen as an alternative to CT scanning for the evaluation of pediatric patients with suspected appendicitis, but the availability of this modality is often limited to daylight hours and weekdays. In one study of after-hours diagnostic imaging for appendicitis, the percentage of patients undergoing US for diagnosis of appendicitis was lower during after-hours time periods than during standard hours—the authors conjecture that surgeons are less confident in after-hours US performed by less experienced ultrasonographers, leading to increased use of CT [42]. Widening the availability of US to after-hours and enhancing the experience of after-hours technologists and radiologists might be necessary if this modality is to be more widely employed. Physicians might be more likely to

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adopt a diagnostic imaging strategy (such as CT) that is always available to them rather than shifting imaging strategies depending on time of day and resource availability. Among other considerations, using a different imaging modality at some times of day might imply deviation from a standard of care. Wider use of MRI is another, although more expensive, imaging strategy to limit CT use. A final element of the solution to the problem of increasing CT utilization is malpractice reform and relief. Reduced CT scan use in emergency departments will likely be accompanied by at least a small increase in delayed or missed diagnoses. Physicians will be extremely reluctant to avoid immediate CT scan if they fear that they will be held responsible and potentially subject to malpractice litigation. The fear of litigation is real, if disproportionate to the risk. A study of closed-claims originating from pediatric emergency departments found 2,283 claims from 1985 to 2000, using a database including 25% of U.S. physicians. With obvious implications for CT utilization, appendicitis was the second most common cause for litigation, and 39% of claims involved allegations of diagnostic error [43]. As a society and a medical system, we must decide whether the priority of reducing radiation exposure is sufficiently important to afford this protection to physicians. We cannot on the one hand expect diagnostic perfection while on the other ask our physicians to restrain their use of a powerful diagnostic tool.

Conclusion CT utilization has increased at a dramatic rate in the pediatric emergency department during the last 6 years. Reductions in radiation exposure from CT are likely achievable through a variety of measures, including better physician and patient education, application of existing clinical decision rules to reduce CT utilization and development of new rules, technical alterations in CT protocols to reduce per-exam exposures, use of alternative imaging modalities such as US and MRI that do not expose patients to ionizing radiation, and expanded use of clinical observation in place of immediate diagnostic imaging. Reform of liability laws might alleviate another driving force behind high CT utilization rates.

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