REVIEW | A Systematic Review of the Cost-Effectiveness of Ultrasound in Emergency Care Settings

BACKGROUND

Ultrasound (US) is safe and effective imaging modality for the rapid diagnosis and management of emergency conditions. Technological advances and the increasing availability of imaging modalities led to expansion of the use of clinical US.

It is assumed that US is cost-effective in emergency care settings given its valuable and rapid diagnostic capabilities, and lower cost when compared to computed tomography (CT) and magnetic resonance imaging (MRI). However, it is unclear whether the published data either support or refute this assumption.

Cost-effectiveness analysis is a tool that combines economic and health outcome data to produce standardized ratios of costs and benefits. The outputs of CEAs allow for comparison of diagnostics that vary by both price and clinical utility and generate important data to support decisions related to health policy and investment.

The authors undertook this project of systematic review of the published evidence surrounding the cost-effectiveness of US in emergency care settings to characterize the existing knowledge regarding the costs and benefits of emergency US, to examine the quality of cost-effectiveness studies and to provide guidance for future research efforts.

MATERIALS AND METHODS

Search strategy

A convenience sample size of 50 participants was used. Participants met the following inclusion criteria: (1) a small infra-renal AAA measuring 30–55 mm in maximal diameter and (2) an ultrasound performed by one of three experienced vascular sonographers using a standardized protocol. Exclusion criteria included patients with a history of previous abdominal aortic surgery.

An interview and physical examination were done upon recruitment.  Relevant medical history and clinical measurements were collected. Ischemic heart disease, hypertension and diabetes were defined as a previous diagnosis or treatment of these conditions by a qualified medical physician. Stroke was defined as a documented history of ischemic or hemorrhagic stroke. The presence of aneurysms at other sites was determined through documented history or relevant medical imaging. Brachial blood pressure, waist circumference and body mass index were measured as part of the study. 

Ultrasound Imaging

A systematic review of the literature was performed using the Preferred Reporting Items for Systematic Review and Meta-Analyses (PRISMA) guidelines. All studies were collated and screened for eligibility through Covidence (www.covidence.org), an online platform for systematic review. Studies were considered for inclusion if they were: (1) economic evaluations that assessed costs and outcomes of comparative strategies; (2) studied the clinical use of US; and (3) took place in an emergency care setting. Two reviewers undertook critical appraisal of the included studies using the CHEERS checklist, which comprises 24 items determined by expert consensus to be of importance when reporting economic evaluations of health interventions.

RESULTS

The electronic searches identified 631 potentially relevant articles following the removal of duplicates. Of these studies, 35 studies met all inclusion criteria and were eligible for data abstraction. They covered a broad range of applications within emergency US. The most comprehensive body of evidence surrounds the evaluation of pediatric appendicitis. This is followed by trauma, echocardiography, obstetric/gynecologic (OB/GYN), biliary, venous, and renal applications. A small group of studies also evaluate general US processes and impact in the emergency department (ED).

Studies evaluating the use of US in pediatric patients for appendicitis universally found that using US as the initial study decreased radiation exposure, overall costs, and length of stay. Six studies that examined US in the setting of acute trauma found that US decreases time to the operating room for patients with injury, decreases the use of CT scans in children, decreases length of stay, and decreases invasive procedures such as peritoneal lavage in adults.

Six studies examined US in the setting of renal, biliary, or venous pathology. One study suggested no efficiency gains with US use due to high numbers of subsequent CT orders, and another found that using US as the initial radiology modality decreases costs and radiation exposure despite a 20% subsequent use of CT to further evaluate patients. Two studies assessed the evaluation of biliary pathology. One study showed that in the evaluation of right-upper quadrant pain, initial point of care ultrasound (POCUS) by ED providers followed by radiology department scans if needed was the most cost-effective approach, and a second study described large costs associated with additional imaging after ED POCUS significant for acute cholecystitis. In the evaluation of venous thromboembolism, protocols using clinical screening tools, D-dimer testing, and US to decrease CT usage were the most cost-effective

Four studies assessed echocardiography in the emergency care setting. One study assessed the cost-effectiveness of a variety of emergency department modalities to evaluate syncope in older patients, finding that CT head and echocardiography where among the most expensive and least revealing tests that are commonly ordered.

CONCLUSION

The authors concluded that despite limited evidence, use of US in emergency care setting is generally cost effective with the strongest evidence of cost-effectiveness exists in the evaluation of pediatric appendicitis and of abdominal trauma, but that more studies are needed to definitively establish the cost-effectiveness of consultative and POCUS across a variety of applications in emergency care settings.