Executing a partial substitution of ultrasound for CT in evaluating appendicitis could slash U.S. healthcare system expenditures by more than $1 billion, according to research conducted at Thomas Jefferson University in Philadelphia and presented at last week’s American Institute of Ultrasound in Medicine (AIUM) annual meeting.
Taking into consideration data from several different sources, Thomas Jefferson University researchers hypothesized that using ultrasound first for evaluating appendicitis in the U.S. could save $1.2 billion and prevent 174 cancer deaths annually by avoiding radiation exposure from CT scans. Their proposed protocol would entail sending patients with positive ultrasound studies directly to surgery and performing a follow-up CT scan on patients with negative results.
The U.S. Centers for Medicare and Medicaid Services (CMS) 5% Carrier, Inpatient, and Beneficiary files for 2007, as well as the Physician/Supplier Procedure Summary master files for that same year, were used to determine the amount and costs of CT and ultrasound performed to evaluate appendicitis. To estimate the national incidence of appendicitis and abdominal pain, the study team examined hospital discharge summaries from the National Center for Health Statistics and the Agency for Healthcare Research and Quality.
Additionally, researchers performed a meta-analysis of 74 recent research studies to determine the positive predictive value of ultrasound and CT for evaluating appendicitis. An estimate of radiation exposure from an average abdominal and pelvic CT was obtained by reviewing 30 consecutive patients from Thomas Jefferson University’s RIS. The study team then extrapolated the Biological Effects of Ionizing Radiation (BEIR) VII model to estimate excess cancer deaths due to CT appendicitis evaluation.
Based on the meta-analysis, ultrasound's sensitivity and specificity were estimated to be 87.5% and 92.7%, respectively, compared with a respective 93.4% and 95.3% for CT. Ultrasound was shown to offer a positive predictive value of 91% for appendicitis; CT, a positive predictive value of 92.5%.
When estimating savings from the suggested ultrasound protocol, the researchers assumed presenting symptoms of right lower quadrant abdominal pain for virtually all of the appendicitis cases. Of the 1.8 million Medicare beneficiaries in the 5% Medicare sample, 650 patients were had appendicitis admissions. Five such patients were double-coded, for a total of 645 unique patients who collectively received a 1,288 CT exams of the abdomen and pelvis.
"There was a ratio of one abdominal and one pelvic CT for every case of appendicitis diagnosed in this country," reports Levon Nazarian MD, of Thomas Jefferson University’s Department of Radiology, in presenting the results of the study on behalf of Lead Researcher Laurence Parker, PhD. However, “less than 4% receive an ultrasound. The cost differences between CT and a limited abdominal ultrasound average $458.53.”
Nazarian adds that there were also 863 admissions for right lower quadrant abdominal pain. Given 650 cases of appendicitis and 863 diagnoses of abdominal pain in the right lower quadrant, he explains, the protocol would result in 1,513 limited ultrasound scans being performed to avoid CT on 569 patients (the result of 650 cases multiplied by 87.5% ultrasound sensitivity).
Moreover, according to the study, imaging cost savings in the 5% Medicare sample would total $177,318 and approximately $3.5 million if extrapolated to the Medicare population as a whole. Based on the estimated discharge survey estimates in the U.S. for appendicitis of 300,000 per year, savings would total $82.5 million, Nazarian concludes.
