Cost and radiation savings of partial substitution of ultrasound for CT in appendicitis evaluation: a national projection.

OBJECTIVE: The costs of an ultrasound-CT protocol and a CT-only protocol for an appendicitis evaluation are compared. For the ultrasound-CT protocol, patients with right lower quadrant abdominal pain undergo an ultrasound examination. If it is positive for appendicitis, they are sent directly to surgery, avoiding CT.

MATERIALS AND METHODS: A comparative effectiveness research study was conducted. The costs of imaging tests, excess surgeries, and excess surgical deaths for the ultrasound-CT protocol and the costs of imaging tests and excess cancer deaths in the CT-only protocol were estimated. Data sources were Centers for Medicare & Medicaid Services (CMS) datasets, national hospital discharge surveys, radiology information system cases, and U.S. Census Bureau life tables. A meta-analysis and sensitivity analyses were also conducted.

RESULTS: The meta-analysis showed a positive predictive value of 92.5% for CT and 91.0% for ultrasound. Analysis of CMS files showed that utilization of CT was almost exactly 2.0 examinations (one abdominal and one pelvic) per patient and for ultrasound was almost nil. The cost of this imaging protocol was $547 per patient, whereas the cost of a limited ultrasound study would be $88 per patient. For the total U.S. population, the cost savings in imaging minus the cost of extra surgeries and extra surgical deaths is $24.9 million per year. Following model VII proposed by the Committee on the Biological Effects of Ionizing Radiation (BEIR), which is known as "BEIR VII," the avoidance of a 12.4-mSv exposure for 262,500 persons would prevent 180 excess cancer deaths. The value of the years of life lost would be $339.5 million. The sensitivity analyses indicate that the cost savings are robust.

CONCLUSION: An ultrasound-CT protocol for appendicitis evaluation offers potentially large savings over the standard CT-only protocol. There are moderate savings from using a less expensive imaging technique despite extra surgeries and large savings from radiation exposure avoided.