Rationale and Objectives
To evaluate appropriate utilization rates for computed tomography (CT) pulmonary angiography (CTPA) in a tertiary center emergency department (ED), before and after a health care provider educational intervention.
Materials and Methods
Institutional Review Board–approved retrospective study. Records for 100 consecutive CTPA studies ordered by the ED were retrieved from a radiology database. Appropriateness rates for the studies were determined using information from existing literature (clinical decision rules and society guidelines). Where pretest probability was not performed, it was calculated by the authors. After ED health care provider education regarding appropriateness guidelines through a dedicated lecture and question-and-answer session, appropriateness rates for another 100 consecutive CTPA ordered by the ED were calculated.
Results
In the preeducational intervention, 1% of patients had Wells scores performed, 65% were women, and 29% were age <40 years. Before CTPA, 40% patients had d -dimer testing, 15% of patients had a “negative” d -dimer, 17% had alternative explanations for chest pain, and 76% had low or intermediate pretest probability. Appropriateness rates for CTPA was 7%, and 8% of studies were positive. Postintervention, no Wells scores were performed, 59% were women, and 34% <40 years. Before CTPA, 32% of patients had d -dimer, 16% had a “negative” d -dimer, 22% had alternative explanations for chest pain, and 84% had low or intermediate pretest probability. The appropriateness rate for CTPA was 6% and 10% of studies were positive.
Conclusion
A single educational intervention had no effect on appropriate utilization rates for CTPA. Repeated and sustained educational interventions may help improve imaging ordering pathways through the ED and other departments.
Pulmonary embolism (PE) is a common and potentially fatal condition that is the second most common cause of sudden unexpected death in outpatients after acute coronary syndrome . The annual incidence is estimated at 23 to 69 per 100,000 of the population . Without treatment, PE has a mortality rate of 30% to 35%, but with therapy, the mortality rate drops to less than 5% . For these reasons, emergency department (ED) physicians frequently consider the diagnosis of PE because rapid diagnosis and treatment can significantly diminish the mortality rate and morbidity of this disease.
The clinical diagnosis of PE can be unreliable because many patients are asymptomatic and do not have clinical signs . In addition, patients may present with vague and nonspecific signs and symptoms resulting from hypotension and cardiogenic shock, which overlap with other entities. In the Prospective Investigation Of Pulmonary Embolism Diagnosis (PIOPED) II study, signs of pulmonary hypertension or right heart overload were detected in only 22% of all patients with PE . The diagnosis of PE is also made difficult because there are myriad risk factors.
Imaging overutilization: PE computed tomography
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Materials and methods
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Table 1
Demographic Characteristics of 100 Consecutive Patients who had CTPA Performed during Their ED Visit before and after a Health Care Provider Educational Intervention
Demographic Characteristic Pre-educational Intervention Post-educational Intervention_P_ Value ( t test) Mean age (range) 47 (18-93) 49 (18-82) .43 Women (%) 65 59 .47 Patients <40 years (%) 29 34 .54 Patients <40 years with indirect CTV performed (%) 93 97 .33 Patients with clinical pretest probability calculated (prediction rule) (%) 1 0 .32 % of patients with d -dimer performed prior to CTPA 40 32 .31 Patients with a “negative” d -dimer result before CTPA (%) 15 16 .85 Patients with alternative explanation for chest pain before CTPA (%) 17 22 .48 Patients with low pretest probability, manually calculated by radiologists (%) 76 84 .22 Prevalence of venous thromboembolism 8% 10% .81
CTPA, computed tomography pulmonary angiography; ED, emergency department; NS, nonsignificant; test, any diagnostic imaging test (eg, CTPA, ultrasound).
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Table 2
Criteria Used to Manually Determine the Appropriateness of Each CTPA Study
Criterion Example Clinical gestalt or clinical prediction rule Note from clinician regarding a “sense” that the patient had PE regarded as appropriate.
Use of a Wells score or other clinical prediction rule with intermediate or high probability result before CTPA regarded as appropriate. Risk factors or clinical signs Risks (immobilization, cancer, hemoptysis, prior DVT or PE, known thrombotic or hypercoagulable state, signs in one leg [or one leg > other], ECG changes S1Q3T3 pattern), summed using the Wells simplified score. Regarded as inappropriate CTPA if score <2. d -dimer testing Not performing a d -dimer on low or intermediate clinical probability patients regarded as inappropriate. d -dimer level At our institution during this study, an ELISA d -dimer level of <1.6 had a negative predictive value of 99% for DVT. A level of <1.6 was thus regarded as “negative.” Performing CTPA on patients with a negative d -dimer regarded as inappropriate. Results of other diagnostic tests Chest radiography demonstrating pneumonia or pneumothorax, or a normal or low probability V/Q study before the CTPA was regarded as inappropriate if no other risk factors.
CTPA, computed tomography pulmonary angiography; DVT, deep venous thrombosis; ELISA, enzyme-linked immunosorbent assay; PE, pulmonary embolism; V/Q, ventilation perfusion scintigraphy.
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Educational Intervention
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Table 3
Subtopics Covered in the 45-Minute Lecture
Subtopic Details Background and scope of problem Epidemiology of venous thromboembolic disease; why VTE is difficult to diagnose clinically Clinical decision rules Why we have them; the application of clinical prediction rules to determine the need for advanced testing; their limitations d -dimer testing Description; different types; indications; the usefulness of d -dimer testing in low and intermediate clinical probability patients; contraindications; limitations The imaging modalities that are available to investigate for PE Chest radiography; ultrasound; ventilation perfusion scintigraphy; CTPE; conventional catheter angiography; magnetic resonance imaging; indications and contraindications and limitations CTPA technique Diagnostic performance, pitfalls, limitations, use of indirect CT venography CTPA appearances Acute PE, chronic PE, acute DVT, chronic DVT, direct and indirect signs VTE Other findings on CTPA CT appearances of atelectasis, pneumothorax, pneumonia, pericardial effusion, acute aortic syndromes Radiation issues Radiation exposure; methods to reduce radiation exposure; comparison with other diagnostic tests; the appropriateness of ultrasound imaging in younger and pregnant patients and alternatives to CTPA in certain patient groups Society Guidelines for Appropriate Utilization of CTPA Including PIOPED investigators, PERC, Fleischner Society, ESC task force guidelines with worked examples for low, intermediate, and high pretest probability patients
CT, computed tomography; CTPA, CT pulmonary angiography; DVT, deep venous thrombosis; ESC, European Society of Cardiologists; PE, pulmonary embolism; PERC, Pulmonary Embolism Rule-out Criteria; PIOPED, Prospective Investigators Of Pulmonary Embolism Diagnosis; VTE, venous thromboembolism.
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Statistical Analysis
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Results
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Discussion
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Limitations
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Conclusion
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Acknowledgment
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