OVERUTILIZING OF COMPUTED TOMOGRAPHY PULMONARY ANGIOGRAM By Curtis Graham RT(R)(VI) A thesis submitted to the School of Radiologic Sciences in collaboration with a research agenda team In partial fulfillment of the requirements for the degree of MASTER OF SCIENCE IN RADIOLOGIC SCIENCES (MSRS) WEBER STATE UNIVERSITY Ogden, Utah December 15, 2023 ii THE WEBER STATE UNIVERSITY GRADUATE SCHOOL SUPERVISORY COMMITTEE APPROVAL of a thesis submitted by Curtis Graham RT(R)(VI) This thesis has been read by each member of the following supervisory committee and by majority vote found to be satisfactory. ______________________________ Dr. Robert Walker, PhD Chair, School of Radiologic Sciences ______________________________ Dr. Laurie Coburn, EdD Director of MSRS RA ______________________________ Dr. Tanya Nolan, EdD Director of MSRS ______________________________________________________________________ Christopher Steelman, MS Director of MSRS Cardiac Specialist iii Abstract Computed tomography pulmonary angiography (CTPA) has evolved into the gold standard diagnostic for confirming the presence of a pulmonary embolism (PE). CTPA has become more readily available at healthcare organizations around the United States. The vast availability of the exam poses some disadvantages regarding patient exposure to radiation and financial implications on both the patients and the healthcare organizations. Prior to CTPA, healthcare professionals are expected to use pre-test algorithms and labs to determine the patient’s probability of having a PE. The D-dimer assay in combination with the Well’s Score are used to categorize patients into either a low or high probability category. Only patients with high probability screens are considered appropriate to undergo CTPA; however, more and more physicians, especially in the emergency room setting, are forgoing the pre-test screening or are not following the guidelines of the pretest probability screens and ordering CTPA exams on patients regardless of their pre-test probability or lack thereof. This literature review was performed to show the significance of the misuse or under-use of the pre-test probability screens for patients suspected of having PE in addition to the severity of the overuse of CTPA. iv Table of Contents Chapter 1: Introduction ....................................................................................................1 Background ...............................................................................................................1 Statement of the Problem ...........................................................................................3 Purpose of the Study ..................................................................................................4 Research Questions ....................................................................................................4 Nature of the Study ....................................................................................................5 Significance of the Study ...........................................................................................5 Definition of Key Terms ............................................................................................5 Summary ...................................................................................................................6 Chapter 2: Clinical Background .......................................................................................6 Introduction ...............................................................................................................6 Etiology .....................................................................................................................7 Epidemiology ............................................................................................................7 Pathophysiology ........................................................................................................8 History and Physical ..................................................................................................8 Evaluation .................................................................................................................9 Treatment / Management Options ............................................................................ 10 Complications .......................................................................................................... 11 Summary ................................................................................................................. 11 Chapter 3: Literature Reviews ....................................................................................... 12 Documentation ........................................................................................................ 12 General Literature Review ....................................................................................... 12 Theme/Subtopic [repeat as needed] ............................ 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Summary ................................................................................................................. 12 Chapter 4: Research Method .......................................................................................... 13 Research Methods and Design(s) ............................................................................. 16 Data Collection, Processing, and Analysis ............................................................... 16 Assumptions ............................................................................................................ 17 Limitations .............................................................................................................. 17 Delimitations ........................................................................................................... 17 Summary ................................................................................................................. 18 Chapter 5: Findings ....................................................................................................... 18 Results ..................................................................................................................... 19 Evaluation of Findings ............................................................................................. 21 Summary ................................................................................................................. 22 Chapter 6: Implications, Recommendations, and Conclusions ........................................ 23 Implications ............................................................................................................. 23 Recommendations.................................................................................................... 23 v Conclusions ............................................................................................................. 23 Appendix A: Wells’ Criteria .......................................................................................... 28 Appendix B: Research Method ...................................................................................... 29 Appendix C: Research Results ....................................................................................... 30 vi List of Tables Table 1. Wells and Modified Wells Score Criteria……………………………………………28 Table 2. Concept and Keyword Mapping Table………………………………………...…….29 Table 3. Features of Studies Included in Literature Review……………………………..30 vii List of Figures Figure 1. PRISMA Research method.……………………………………………………….29 1 Overutilizing of Computed Tomography Pulmonary Angiogram Chapter 1: Introduction Pulmonary embolisms (PE’s) occur when one or more blood clots make their way from the legs or other parts of the body and become blockages in the arteries of the lungs. PE’s are responsible for 5–10% of all hospital deaths in the United States. 1 Wells’ criteria and Modified wells score (MWS) in conjunction with a D-dimer assays are used to calculate pretest probability (PTP) of PE.1–4 The Wells score and its simplified version have been accepted as the most cited clinical criteria for categorizing PTE probability into likely and unlikely clinical risk groups.2 Patients determined to have a high probability of PE usually undergo Computed tomography pulmonary angiography (CTPA) to confirm the diagnosis. 1,3–5 The high sensitivity and specificity of CTPA has led it to become the gold standard for confirming acute PE diagnoses. The combination of low PTP and a low D-dimer excludes the diagnosis of PE with a negative predictive value of 99%.1 Numerous retrospective studies1–5 have shown that many physicians are not in compliance with using the Wells score and D-dimer labs adequately to determine PE probability. For example, statistics spanning from 2005 to 2010 indicated approximately 2.5% of the 120 million patients seeking care in the United State’s EDs underwent CTPA and during that same period, the rate of PE diagnosis in the same group declined to 3%. The annual ordering rate of CTPA scans from US EDs between 2005 and 2010 exhibited a 28% growth, while the yield rate showed a decline.4 Another example from 2005 to 2015 revealed similar findings regarding CTPA increase and decline in yield; however, this study also noted that the rate of hospitalizations for PE increased while the mortality rate for PE remained consistent. 6 The misuse or under-use of the pre-test probability screening methods result in excess 2 and unnecessary CTPA exams being performed in both the inpatient and emergency room setting. Patient safety is the number one priority for Radiographers; reducing over exposure to radiation as well as decreasing misuse and overuse of various exams are important factors in ensuring safety measures and protocols are being followed. 2,4,5 Background Numerous studies have shown that, both historically and presently, many physicians are not adherent with the guidelines for determining pre-test probability for PE prior to ordering CTPA exams. In some cases, the algorithms or labs are not completed in their entirety prior to CTPA orders and in other cases CTPA is being ordered despite low probability findings in the pre-test screening. As one would imagine, most of the CTPA exams performed on patients with pre-determined low probability for PE yield negative results. Concerns regarding the overutilization of CTPA scans have largely arisen from data collected in American emergency departments, where the diagnostic yield can be as minimal as 5%. Although the definition of an 'ideal' CTPA yield is subject to some debate, the Royal College of Radiologists in the United Kingdom stipulates that pulmonary embolism (PE) should be identifiable in a minimum of 15% of CTPAs, and other diagnoses should be evident in at least 50% of the conducted scans. 7 In one retrospective chart review performed by Michigan State University it was revealed that of the 295 patients for whom CTPA was ordered in the emergency department to rule out PE, only 5.4% yielded results positive for PE with 41% of the CTPAs performed being inappropriately ordered in this first place.1 Overuse of CTPA is a real problem, which over-exposes patients to unnecessary amounts of radiation and is a strain on the finances of both the patients and healthcare organizations involved. 3 Statement of the Problem CTPA exams are being overused or misused in the emergency department setting in the process of confirming the diagnosis of PE; this problem arises from non-adherence with the pre-test probability screening guidelines. CTPA exams are being performed in staggering numbers secondary to noncompliance with pretest probability protocols; this holds true in the emergency room setting resulting in misuse of resources, time, and imposing health risks on patients secondary to exposure to unnecessary amounts of radiation. Multiple studies have confirmed a lot of organizations are not in compliance with using the Well’s score coupled with D-Dimer labs prior to making the decision to perform imaging; thus, a profound amount of CTPA exams are being performed unnecessarily.1,2 The concern for over testing for PE is not new; this has been an issue for many years. Again, numerous studies across the United States have been performed to prove the ongoing overuse of CTPA exams. For example, data from 2005 to 2010 suggested that about 2.5% of the 120 million patients who visit emergency departments (EDs) in the United States have computerized tomographic pulmonary angiography (CTPA) done, while the rate of PE diagnosis in the same sample has dropped to 3%. 4 The pre-screening tools to detect PE probability were put into place to limit the amount of unnecessary CTPA exams being performed.4 Specific to PE, recommended methods include the use of clinical criteria, namely the pulmonary embolism rule-out criteria (PERC rule) and the Ddimer assay in patients in EDs, with nonhigh clinical probability for PE. 4 The desired methods for diagnosing PE in the emergency room setting includes using the pre-test probability screens as they were intended as opposed to ordering CTPA exams on patients 4 who were either yielding low probability results or whose pretest screens weren’t done appropriately or at all. Current studies are still showing that CTPA exams are being ordered in excess on low probability cases proving this issue continues to warrant ongoing investigation in an effort to remedy the problem. Consequences of turning a blind eye to this issue could have substantial financial implications on both patients and healthcare organizations. Purpose of the Study This literature search review was performed to investigate the significance of the misuse or under-use of the pre-test probability screens for patients suspected of having PE in addition to the severity of the overuse of CTPA. This study was performed by examining the data and findings from seven research studies related to this issue. Research Questions Q1. Are CTPA exams being misused or overused in the emergency room setting? Q2. Are clinicians in compliance with the pre-test probability screening tools for determining low or high probability for PE prior to ordering CTPA? Hypotheses H10. CTPA exams continue to be both misused and overused in the emergency room setting as physicians are either not in compliance with utilizing the Wells Scoring guidelines and/or D-dimer labs or CTPA exams are still being ordered despite lowprobability scoring prior to the exam. 5 Nature of the Study This literature review was performed utilizing the PRISMA guideline method. The peer reviewed data for this study was obtained from the National Library of Medicine journals dated between January 1, 2019, through January 1, 2023. A systematic search strategy was followed, all information obtained is transparent and repeatable. Significance of the Study This study is significant because further case study research continues to show that proper protocols are not being utilized prior to ordering CTPA exams. Placing further emphasis on this issue would be a step in the right direction towards developing quality improvement projects aimed at educating and accouraging physicians to comply with the current guidelines. Accountability should be placed on clinicians and organizations who continue to demonstrate non-compliance with the current set protocols. CTPA is an expensive diagnostic and requires the use of high doses of radiation. If the exam is performed on patients yielding low probability for PE, then this can place avoidable health risks on patients and pose otherwise avoidable financial implications on both the patients and healthcare organizations. Definition of Key Terms Term 1. Computed tomography pulmonary angiography (CTPA)- is a specialized CT scan designed to detect the presence of blood clots within the lungs, a condition referred to as pulmonary embolism or PE. This imaging procedure captures images of the blood vessels responsible for transporting blood from the heart to the lungs, specifically focusing on the pulmonary arteries.8 6 Term 2. Pulmonary embolism (PE)- The blockage of pulmonary arteries by blood clots that originate elsewhere, usually in the major veins of the legs or pelvis 9 Term 3. Wells Score and Modified Wells Score (MWS)- is the best-known clinical probability assessment tool for clinically suspected DVT. It is a straightforward point-score system with a maximum of eight score points. 10 Term 4. D-Dimer- is a protein that the body releases when blood clots break down. Its presence in the blood or urine may indicate that a person developed a clot.9 Summary CTPA is being overused in the emergency room setting secondary to nonadherence with pre-test probability screening tools. The purpose of this study is to investigate the significance of CTPA overuse by reviewing the data from previous research studies related to this issue. This is a literature review aimed at reviewing data from seven peer reviewed case studies to further investigate the issues of practitioners failing to properly utilize pre-test probability screens prior to ordering CTPA. Chapter 2: Clinical Background Introduction Pulmonary Embolisms (PE) are sudden blood clots or blockages of the pulmonary arteries; these types of blockages usually occur as a result of blood clots breaking off from deep veins in the legs which then travel to the pulmonary arteries in the lungs.9 Pulmonary embolism (PE) is a common disease in the USA responsible for 5–10% of all hospital deaths and an estimated 100,000–200,000 annual death.1 PE can vary in both severity and symptoms; furthermore, in many cases the condition can be fatal if left untreated or if treatment is delayed. Early detection of the condition is elemental in 7 treating PE so it is no surprise, with the vast availability and efficiency of computed tomography pulmonary angiography (CTPA), that this particular exam has become the gold standard exam in diagnosing PE.1 CTPA is not a cheap exam and it exposes patients to large amounts of radiation; this is why pre-test probability screens are supposed to be performed prior to ordering such an exam. Less frequent yet noteworthy outcomes associated with contrast-enhanced imaging, like CTPAs, encompass contrast extravasation and anaphylaxis. Notably, the emergency department (ED) within hospital settings has been pinpointed as a potential site where the excessive utilization of this imaging could be significant, which may, in turn, lead to patient harm and escalating healthcare expenses.7 Etiology Most commonly, pulmonary embolisms are caused by the breaking off of deep vein thromboses (DVT) located in the legs. These blood clots travel to the lung where they become lodged in the pulmonary arteries. Other causes of PE include air bubbles, upper body DVT, fat emboli which can occur after broken bones, and tumors. Risk factors for PE include cancer, heart disease, personal or family history of blood clots or clotting disorders, and long-term use of birth control pills or estrogen therapy. A pulmonary embolism is also more likely to develop after childbirth, heart attack or stroke, long plane or car rides, long-term bedrest, severe injuries (burns or fractures), or surgery.11 Epidemiology The incidence of thromboembolism in the United States, which has been shown to rise with age, is approximately 1-2 per 1,000. Incidence is greater in males, but women 8 have a slightly increased risk during reproductive years. Some studies have shown that the increasing use of CT scanning has led to an increase in reported incidences of confirmed PE. In terms of mortality, venous thromboembolisms account for approximately 100,000 deaths per year in the US. 12 Pathophysiology Pulmonary Embolisms arise from deep venous thrombi that may dislodge from their vessels of origin and travel through the vascular system to the right side of the heart. From the right side of the heart, these clots will make their way into the pulmonary arteries, either partially or completely occluding one or multiple vessels. Numerous factors, including underlying comorbid conditions and size of the emboli, can contribute to the severity of pulmonary embolisms and their resulting symptomology.9 History and Physical Small emboli can be asymptomatic, easy to treat, and fast to lyse and resolve. Large emboli can have far more severe physiologic effects on the patient’s overall health resulting in hypoxemia with resp distress, lung collapse, right ventricular failure, and death. Emboli may cause acute dyspnea (shortness of breath) and, when pulmonary infarction is present, pleuritic chest pain is a common finding. Patients with PE may describe dyspnea as being worse with activity and exertion but minimal or resolved with rest. Less common symptoms may include coughing and hemoptysis. Geriatric patients may present with initial complaints of altered mental status. Tachycardia and tachypnea are the most common complaints in patients with PE. Massive pulmonary emboli may manifest with hypotension, tachycardia, lightheadedness/presyncope, or cardiac arrest. Upon auscultation of the heart, a loud S2 9 secondary to a loud pulmonic component may be heard, yet not likely to be heard in an acute PE. In patients with underlying comorbid diseases, especially chronic respiratory and cardiac diseases, crackles and wheezing may be heard within the lungs. In severe circumstances where left ventricular failure has occurred, patients may display jugular venous distention and/or S3 with or without tricuspid regurgitation may be heard.9 Evaluation In diagnosing PE, clinicians may have a high index of suspicion and will use their best judgement to determine the likelihood of PE. Pretest probability screening tools and subsequent testing based on the pretest probability results will be performed. In determining clinical probability of PE, the combination of chest x-ray results, ECG results, and findings from the physical exam are used. While chest x-ray may not confirm the presence of PE, it may identify other issues which could arise from an underlying PE. Oxygenation can be assessed using pulse oximetry and arterial blood gas results. Clinical prediction scores, such as the Wells score or the revised Geneva score, or the Pulmonary Embolism Rule-Out Criteria (PERC) rule, may aid clinicians in assessing the chance that acute pulmonary embolism is present.9 Pretest probability screens should be performed before the decision to perform more sensitive imaging is made. Pretest probability guides testing strategy and the interpretation of test results. In calculating the Wells score, a point system using different assessment variables is utilized. See Table 1 for Modified Wells Scoring Criteria. If a patient has a score of 4 or lower and the D-dimer test returns a negative result, there seems to be no need for additional tests. When the score exceeds 4, additional assessment is warranted, and typically, computed tomographic angiography (CTA) is conducted. Nevertheless, it's crucial to prioritize clinical judgment based on 10 high suspicion levels, even if the Wells score is low. If a patient is determined to have low probability of PE, then only minimal testing should be ordered. D-dimer testing may be performed in circumstances of low or intermediate probability and if found to be negative then this is highly indicative that there is no PE present. Given the accuracy and high sensitivity of the exam, CT angiography is the preferred imaging modality for diagnosing pulmonary embolism. If pretest probability yields high results or if the Ddimer is found to be elevated, then CTPA is usually ordered to confirm or denounce the presence of PE. In patients with renal insufficiency, alternate testing without the use of contrast is considered (VQ scanning).13 Treatment / Management Options Pulmonary Embolism treatment will vary from case to case and will be based on the degree of risk involved. Supportive therapy could include providing oxygen supplementation for hypoxemia and respiratory symptoms, IVF resuscitation for low blood pressure, and in more severe cases of hemodynamic instability vasopressor drugs may be warranted. Anticoagulant drug examples include IV unfractionated heparin (heparin drips), subcutaneous low molecular weight heparin (Lovenox injections), factor Xa inhibitors (oral Eliquis or Xarelto), and patients with heparin induced thrombocytopenia will require direct thrombin inhibitors (Argatroban or Bagatran). Low risk patients may only require anticoagulation, whereas high risk patients may require both anticoagulation therapy as well as more invasive measures to treat the clot burden (systemic thrombolysis or surgical catheter-directed therapy). During treatment, intermediate risk patients require ongoing assessment for deterioration and will usually require acute hospitalization. High risk PE patients may find themselves being 11 treated in the critical care setting; these patients may have extensive clot burden, RV compromise, significant hypoxemia or respiratory failure, low or borderline blood pressure, or may experience clinical deterioration. Low risk PE patients may also require hospitalization for treatment, but the hospital stay is usually shorter and for observation purposes only. Outpatient management is appropriate for some low-risk PE cases where the clot burden is low, and symptoms are mild or absent. Hemodynamically stable patients who are deemed appropriate for outpatient care should receive proper education regarding their PE diagnosis and treatment plan; as always, appropriate follow-up appointments should be set.9 Complications A primary complication of anticoagulant medications is bleeding; other complications may include hives or anaphylaxis. Patients with PE usually require maintenance anticoagulation as a form of prophylaxis against new clot formation and further embolization. Patients receiving anticoagulation therapy need to be monitored for bleeding and bleeding risks before, during, and after treatment. Thrombocytopenia and Heparin-induced thrombocytopenia (HIT) occurs secondary to excessive platelet clumping and may result from IV unfractionated heparin therapy. If patients develop low platelet levels, new thrombosis, or bleeding then heparin therapy should be stopped as soon as possible.9 Summary Pulmonary embolism diagnoses are common in the USA and usually arise from blood clots traveling from the extremities to the pulmonary vessels in the lungs. Symptoms can range from asymptomatic to severe and treatment will vary depending on 12 the degree of risk associated with each case. Diagnosing pulmonary embolism begins with clinical assessment of presenting symptoms and complaints. Further steps for diagnosing PE involve the assessment of pretest probability where those determined to have high probability of PE undergo further imaging (CTPA) to confirm PE diagnosis. Treatment of confirmed PE will vary depending on severity but will usually include some form of anticoagulation, symptom management, and in more severe cases, thrombolysis or invasive measures may need to be taken. Chapter 3: Literature Reviews Documentation In the initial search strategy in the National Library of Medicine between January 1, 2019-2023, the concepts and keywords listed in Table 2 yielded 54 articles. The total amount of duplicate articles removed was 31. The total number of actual articles reviewed was 23. A total of six articles were deemed irrelevant and removed; furthermore, 10 articles were removed having been missing viewable full text. Seven total articles were left for review upon completion of narrowing the sources. General Literature Review This literature search review was performed to investigate the significance of the misuse or under-use of the pre-test probability screens for patients suspected of having PE in addition to the severity of the overuse of CTPA. This study was performed by examining the data and findings from seven research studies related to this issue. Non-adherence to Pre-test Probability Screens: Wells Score and D-Dimer The Wells score is a clinical prediction tool founded on uncomplicated, noninvasive clinicals factors. It has undergone refinement and validation over time, 13 proving its utility in assessing the pretest probability of suspected PE. If a patient yields a score of 4 or less in addition to a negative D-dimer test then no further testing for PE should be necessary. If the score is found to be greater than 4 then further evaluation is warranted and, in this case, the use of CTPA is usually justified.10 See Table 1 for details regarding calculating Wells score and its usefulness in calculating pre-test probability of PE.14 This literature review shows numerous examples detailing how physicians are not compliant in the use of the Wells score coupled with the D-dimer in determining pretest probability in the ED. Either the pre-test screens are incomplete or CTPAs are being performed regardless of low probability findings prior to the exams. Summary In summary, seven articles were filtered out for review regarding physician noncompliance with pre-test probability screens for PE and overuse of CTPA. Over time, the Wells score has undergone refinement, validation, and has proven to be valuable in ascertaining the pretest probability for suspected PE. If patient yields low probability results on the Wells score coupled with a negative D-dimer then CTPA is usually not necessary. Numerous studies have consistently demonstrated that when patients present with both a low clinical probability, as determined by the Wells score, and normal Ddimer levels, the probability of pulmonary embolism is exceedingly low. In such cases, additional imaging is typically unnecessary, and withholding anticoagulation can be done safely. 10 Chapter 4: Research Method CTPA exams are being overused or misused in the emergency department setting in the process of confirming the diagnosis of PE; this problem arises from non-adherence 14 with the pre-test probability screening guidelines. CTPA exams are being performed in staggering numbers secondary to noncompliance with pretest probability protocols; this holds true in the emergency room setting resulting in misuse of resources, time, and imposing health risks on patients secondary to exposure to unnecessary amounts of radiation. Multiple studies have confirmed a lot of organizations are not in compliance with using the Well’s score coupled with D-Dimer labs prior to making the decision to perform imaging; thus, a profound amount of CTPA exams are being performed unnecessarily.1,2 The concern for over testing for PE is not new; this has been an issue for many years. Again, numerous studies across the United States have been performed to prove the ongoing overuse of CTPA exams. For example, data from 2005 to 2010 suggested that about 2.5% of the 120 million patients who visit emergency departments (EDs) in the United States have computerized tomographic pulmonary angiography (CTPA) done, while the rate of PE diagnosis in the same sample has dropped to 3%. 4 The pre-screening tools to detect PE probability were put into place to limit the amount of unnecessary CTPA exams being performed. In the context of pulmonary embolism (PE), the recommended approaches involve the utilization of clinical criteria, specifically the pulmonary embolism rule-out criteria (PERC rule) and the D-dimer assay. These methods are typically applied to patients in emergency departments (EDs) who do not exhibit a high clinical probability for PE. 4 The desired methods for diagnosing PE in the emergency room setting includes using the pre-test probability screens as they were intended as opposed to ordering CTPA exams on patients either yielding low probability results or whose pretest screens weren’t done appropriately or at all. Current studies are 15 still showing that CTPA exams are being ordered in excess on low probability cases proving this issue continues to warrant ongoing investigation in an effort to remedy the problem. The consequences of turning a blind eye to this issue could have substantial financial implications on both patients and healthcare organizations. This quantitative study was performed to investigate the significance of the misuse or under-use of the pre-test probability screens for patients suspected of having PE in addition to the severity of the overuse of CTPA. This chapter will discuss the research methods and design of the research used to address the problem: the overuse or misuse of CTPA exams in evaluating patients suspected of having PE. The research methodology will be broken down to reveal the population of patients used to collect the data needed to confirm the presence of the problem at hand. Limitations and delimitations in performing this study will be revealed. This chapter will be concluded with a synopsis of this research method. Research Questions Q1. Are CTPA exams being misused or overused in the emergency room setting? Q2. Are clinicians in compliance with the pre-test probability screening tools for determining low or high probability for PE prior to ordering CTPA? Hypotheses H10. CTPA exams continue to be both misused and overused in the emergency room setting as physicians are either not in compliance with utilizing the Wells Scoring guidelines and/or D-dimer labs or CTPA exams are still being ordered despite lowprobability scoring prior to the exam. 16 Research Methods and Design(s) This literature review was obtained by searching peer-reviewed journals published in English from Jan 1, 2019, through January 1, 2023. Utilizing the PRISMA guidelines a systematic search strategy was performed that is transparent and could be duplicated. The database of the National Library of Medicine was searched for eligible articles. Searches were performed applying a combination of keywords related to the concepts of overutilizing, computed tomography pulmonary angiography, and emergency department; see Table 2. There was a full analysis of all viewable articles and any that did not meet the requirements were excluded. Data Collection, Processing, and Analysis The literature search encompassed a review of studies published in English within peer-reviewed journals between January 1, 2019, and January 1, 2023. A systematic search strategy was executed in adherence to PRISMA guidelines, ensuring a methodical, transparent, and reproducible approach.15 The National Library of Medicine database was consulted for eligible articles. The search incorporated a combination of keywords associated with overutilization, computed tomography pulmonary angiography, and emergency departments (as indicated in Table 2). Each article's titles and abstracts underwent a comprehensive analysis, and those that did not directly pertain to the utilization of CTPAs in emergency departments were excluded. Subsequently, papers with potential relevance were subjected to full-text analysis for eligibility. The flow chart in Figure 1 illustrates the process of identifying, screening, and including articles in this review. 17 Assumptions It was assumed that emergency rooms are performing unnecessary CTPA in high numbers. In looking at the data, it was pre-determined that the majority of CTPA exams performed on patients who yielded low probability after pre-test screening would be negative for PE. Limitations The literature review was performed using the National Library of Medicine which is a collection of peer-reviewed studies from 2019 to 2023 and although it’s linked to other databases it is still limited because there may be additional non-peer reviewed data that remains un-published or further studies that do not fall within the date range used that could offer useful insight into this issue. Delimitations To narrow the scope of the study, specific keywords were used in searching the National Library of Medicine for relevant material. The initial search yielded a total of 54 studies. A total of 31 articles were removed for being duplicates. Of the 23 remaining articles, 6 were removed for irrelevance and 10 were removed secondary to unviewable texts and information. After narrowing the search material, a total of 7 articles remained. Of the 7 studies used, each had something different and relevant to add to the scope of this literature review with the end results all proving CTPA exams are being overused and ordered without the proper use of pre-test probability screens. 18 Summary This study sought to investigate physician non-adherence with pre-test probability screens for PE in relation to overuse or misuse of CTPA exams in the ED. The assumption is that ED physicians are still non-adherent with pre-test probability screens resulting in ordering of excess, unnecessary CTPA exams. Data for this study were gathered through an extensive search of peer-reviewed journals published in the English language, spanning from January 1, 2019, to January 1, 2023. The research followed the PRISMA guidelines, ensuring a systematic and transparent search strategy that could be replicated. To identify relevant articles, the National Library of Medicine database was thoroughly examined. The search process involved a combination of keywords related to the topics of overutilization, computed tomography pulmonary angiography, and the emergency department. Limiting this study was the lack of access to non-published data on the National Library of Medicine database which may offer further useful insights into this investigation. A total of seven articles remained after narrowing the search, all offering relevant and detailed information for this literature review. Chapter 5: Findings This research study investigates the significance of the misuse or under-use of the pre-test probability screens for patients suspected of having PE in addition to the severity of the overuse of CTPA in the ED setting. CTPA exams are being performed in excess despite low and/or incomplete pretest probability screens; of the avoidable CTPAs performed, most are yielding results negative for PE. Unnecessary CTPA testing may impose multiple health risks on patients and place significant financial implications on both the patients and healthcare organizations. 19 Results 5a. Use of CTPAs As anticipated, strong evidence was found to suggest CTPAs are being overused in the emergency room setting. Higashiya et al. investigated 23 ED physicians and it confirmed substantial variability between the number of CTPAs ordered, as well as the positivity rates of PE in their patients. Among the results, the median positivity rate was 7.7%, with a range of 0% to 18.4%.16 With 15% being the ideal CTPA positivity rate, the 7.7% positivity rate found in this study was almost half below the desired rate. Furthermore, it was determined CTPAs were being performed unnecessarily with 49.5% of CTPAs conducted in the ED determined to be avoidable.7 The exams were avoidable because they were conducted despite prior low pre-test probability screens or incomplete pre-test probability screens. In another study that analyzed data from 661 patients, clinical prediction rules were documented in only 15 patients (2.3%). Out of the total, 422 patients (63.8%) had the necessary information related to modified Wells criteria and D-dimer assays and were thus included in the subsequent analysis. Among the included patients, pulmonary embolism (PE) was detected in 22 individuals (5.21%) categorized as "PE unlikely" based on the modified Wells score (mWS ≤4) and 1 patient (0.24%) who tested negative for D-dimer. Additionally, 30 patients (7.11%) met the criteria for avoidable CTPA (both D-dimer negative and PE unlikely), with dyspnea being significantly associated with this group. 17 20 5b. Use of D-dimer The use of the D-dimer assay is debatable amongst physicians for various reasons. Some physicians believe D-dimer is too widely used amongst patients with low clinical suspicion of PE. In an actual interview with physicians it was discovered that doctors felt obligated to order CTPA in patients with elevated D-dimer despite the known false positivity rate.7 Another study was performed showing the rate of actual positive CTPA results yielded after low or intermediate D-dimer results. This group of researchers noted the measured D-dimer results from 568/909 (62.5%) and 597/955 (62.5%) of patients who were either in the low or intermediate-risk groups according to the Wells score. They found 461 (81.1%) and 488 (81.7%) patients had positive age-adjusted D-Dimer and of those, only 139 (30.2%) and 155 (31.8%) patients were confirmed positive for PE via CTPA.14 5c. CTPAs being Ordered Inappropriately It has been suggested numerous times that clinicians are not in compliance with pretest probability screens prior to ordering CTPAs. One study performed by Roy et al. in which 381 CTPAs were ordered, only 12% of the CTPAs were positive for PE and 88% of the exams were negative for PE. In the same study, pre-test probability screens were only performed on 36% on the selected cases; of those 36%, only 26% were concluded to be likely of having PE and 74% deemed unlikely for having PE. From the 74% of the low-probability cases, 68.9% did not receive a D-dimer, 29.7% received a D-dimer, and only 1.4% yielded positive D-dimer.18 21 5d. Risks Associated with Overuse of CTPA A radiographer’s first priority is patient safety and performing CTPAs on patients unnecessarily exposes them to high doses of radiation. CTPAs also place financial implications on both, the patients and the healthcare organizations. In addition to health and financial risks involved with CTPAs, there is also a risk for misdiagnosis or incidental findings. In a recent Canadian study performed at tertiary EDs in which 1708 CTPAs were conducted, 13.1% resulted in other incidental findings and 13.6% yielded positive PE results. Only 11.7% of the 223 incidental findings were clinically significant requiring further treatment. Overusing CTPAs leads to potential detection of nonsignificant PEs; this increases patient’s risks in terms of adverse treatment effects.6 Evaluation of Findings The findings in this literature review suggest that CTPA is still being overused in the ED setting despite pretest probability screening protocols and guidelines. Approximately half of the CTPAs being performed in the ED setting were determined to be avoidable. Studies performed regarding D-dimer testing on patients with low or intermediate risks have found that only about 30-31% of those patients yielded CTPA results positive for PE. Most of the reasons for this non-compliance issue are unknown or have not yet been proven, however, interviews with ED doctors revealed that physicians have many concerns with using D-dimer assays in pretest screening for CTPA and many still feel obligated to perform CTPA with positive D-dimer results despite the parameters set by the screening tools. See Table 3 for pertinent data and findings from each of the 7 studies reviewed. 22 Summary CTPAs are being performed in excess in the ED setting despite patients yielding low pretest probability screens. Very few CTPAs performed on low-probability cases yield results positive for PE. Furthermore, the use of D-dimer testing in pre-test screening for PE is debatable amongst physicians for various reasons, but mostly because of concerns surrounding the false positivity rates of D-dimers. The practice of performing unnecessary CTPAs is financially wasteful for healthcare organizations in terms of time and utilization of resources. Unnecessary imaging also poses health implications on patients and puts them at risk for exposure to unnecessary amounts of radiation, misdiagnosis, incidental findings, hospitalization not related to PE, and possible adverse effects of medical therapy. 23 Chapter 6: Implications, Recommendations, and Conclusions CTPA exams are being overused or misused in the emergency department setting in the process of confirming the diagnosis of PE; this problem arises from non-adherence with the pre-test probability screening guidelines. This quantitative study was performed to investigate the significance of the misuse or under-use of the pre-test probability screens for patients suspected of having PE in addition to the severity of the overuse of CTPA. This study was performed by examining the data and findings from seven research studies related to this issue. This was a retrospective review of data previously collected which poses some limitations to findings. This chapter will discuss the implications of this research for practice. Recommendations regarding further research and investigation into this issue as well as a conclusion will be devised. Implications This literature review discussed in detail the evidence obtained proving CTPA exams are being overused and ordered inappropriately without prior or proper use of pretest probability screens; however, the articles reviewed offered very limited explanations as to why this is still an issue. Various explanations from the authors suggested possible explanations for the overuse of CTPA but of the seven articles reviewed, only on study took a qualitative approach in which physicians were actually interviewed to gather explanations for the ordering trends. Recommendations Numerous studies reviewed concluded that CTPAs were being overused in the emergency room setting and many studies suggested the reason for this is that physicians were not in compliance with the pre-test probability screening tools. Very limited 24 information was available detailing why the scans were being overused in the ED. Further case studies involving more in-depth physician interviews into this issue may be useful in identifying and addressing MD concerns with the pretest screening tools. This issue is one of quality improvement and implementing projects to encourage physicians to adhere to the protocols and guidelines already in place is recommended. Emphasizing evidence-based clinical decision support systems regarding CTPA overuse or misuse could also help in persuading doctors to adhere to protocols. Including the pretest probability screens in the order sets (EMR-embedded algorithm) for CTPA and including the radiologists in the decision to perform the exam may be useful in targeting possible inappropriate exams, trending the ordering habits of the providers, and safeguarding patients and organizations from potential unnecessary CTPA testing. Conclusions CTPA is consistently demonstrated to be excessively utilized in emergency departments globally through repeated case study reviews over the years. The overuse of this exam leads to health implications for the patients and financial implications for both the patients and the healthcare organizations involved. Numerous studies suggest that while pretest probability screens are in place, ED clinicians continue to be non-adherent with the set protocols and continue to order unnecessary CTPAs in excess. This literature review highlights the need for further education and research regarding CTPA misuse. Further one-on-one research with ED physicians is needed to investigate why they are not compliant with pretest probability screens and why CTPA exams continue to be ordered in excess despite low pretest probability results. There are several potential strategies that could combat this issue in the clinical setting including, but not limited to: embedding the 25 pre-test probability screens in the EMR and order sets, including Radiologists in the decision to perform CTPA, implementing quality improvement measures to provide further education or possible incentive to physicians for adhering to proper guidelines, and continuing to conduct research into physician’s areas of concerns with pretest screening tools. 26 References 1. Osman M, Subedi SK, Ahmed A, et al. Computed tomography pulmonary angiography is overused to diagnose pulmonary embolism in the emergency department of academic community hospital. 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Accessed October 8, 2023. https://www.uptodate.com/contents/image?imageKey=PULM%2F54767 15. Liberati A, Altman DG, Tetzlaff J, et al. The PRISMA Statement for Reporting Systematic Reviews and Meta-Analyses of Studies That Evaluate Health Care Interventions: Explanation and Elaboration. PLOS Medicine. 2009;6(7):e1000100. doi:10.1371/journal.pmed.1000100 16. Higashiya K, Ford J, Yoon HC. Variation in Positivity Rates of Computed Tomography Pulmonary Angiograms for the Evaluation of Acute Pulmonary Embolism Among Emergency Department Physicians. Perm J. 2022;26(1):58-63. doi:10.7812/TPP/21.019 17. Almarshad F, Alaklabi A, Raizah AA, et al. Diagnostic approach and use of CTPA in patients with suspected pulmonary embolism in an emergency department in Saudi Arabia. Blood Res. 2023;58(1):51-60. doi:10.5045/br.2023.2023007 18. Roy B, Nelson J, Olson S, et al. The Use of CTPA in ED and Inpatient Settings for Evaluation of PE: Are We Choosing Wisely? :1. 28 Appendix A: Wells’ Criteria Table 1. Wells and Modified Wells Score Criteria Wells criteria and modified Wells criteria: Clinical assessment for pulmonary embolism Clinical symptoms of DVT (leg swelling, pain with palpation) Other diagnosis less likely than pulmonary embolism Heart rate >100 Immobilization (≥3 days) or surgery in the previous four weeks Previous DVT/PE Hemoptysis Malignancy Probability Traditional clinical probability assessment (Wells criteria) High Moderate Low Simplified clinical probability assessment (Modified Wells criteria) PE likely PE unlikely a Data adapted from UptoDate14 3.0 3.0 1.5 1.5 1.5 1.0 1.0 score >6.0 2.0 to 6.0 <2.0 >4.0 ≤4.0 29 Appendix B: Research Method Table 2. Concept and Keyword Mapping Table Concept 1 Overuse Overutilized, overused, over used, over-used Concept 2 Computed Tomography Pulmonary Angiogram CTPA, computed tomography pulmonary angiography, CT pulmonary angiogram, Ct pulmonary Concept 3 Emergency Department ED, emergency Room, ER *Each keyword within a concept utilized ‘OR’ for search criteria; each concept was linked with ‘AND’ Figure 1. PRISMA Research method. Summary of articles identified, screened and included in literature review, adapted from Thurlow et al.7 Total articles identified through the National Library of Medicine from January 1, 2019-2023: (n=54) Total articles removed for being duplicate. (n=31) Total articles reviewed: (n=23) (6) Total articles removed for being irrelevant. (10) removed for full-text not being reviewable (n=16) Article included. (n=7) 30 Appendix C: Research Results Table 3. Features of Studies Included in Literature Review. Author(s) Year Country Study Design Volume % of CTPA w/ D-dimer % of CTPA w/ PE Kline et al. (Study 1) Kline et al. (Study 2) Roy et al. 2020 29.6% 1.3% 21,037 53% 4.8% - 381 31.1% 12% - 2023 661 63.8% 9.01% 1380 50.5% 6.9% .24% (1) - 2023 2758 undefined 2021 Finland 1001 62.5% 12.4% (mean) 22.2% Youens et al. 2023 Australia Retrospective Study Retrospective study Retrospective study Retrospective study Retrospective study Retrospective Study Retrospective study Retrospective observational cohort study 21,230 Almarshad et al. Higashiya et al. Thurlow et al. Kauppi et al. United States United States United States Saudia Arabia United States Australia PE unlikely patient w/ -Dimer and +PE - undefine d - 2020 2022 a 2022 14.1% (mean) 1.85% (2) - Mean was calculated if there were multiple sites or years used in the respective study. b The results have been calculated from the information presented within the study.