CT contrast-medium dosing by weight saves money

Last Updated: 2017-01-26

By Lorraine L. Janeczko

NEW YORK (Reuters Health) - For abdominal CT, basing the contrast-medium dose on weight and allowing a smaller maximum volume saves money, according to new research.

"Health systems can achieve substantial cost and utilization reductions on contrast-enhanced CT when they adopt a lower-volume but equally efficacious contrast-material dosing strategy," said lead author Dr. Matthew S. Davenport of the University of Michigan Medical School in Ann Arbor.

"We can do an equivalent or more effective job making a diagnosis while reducing expenses and delivering the right dose to the patient at the same time - the very definition of quality care," he told Reuters Health by email.

Dr. Davenport and his colleagues investigated the cost savings by switching from a fixed-volume, low-osmolality iodinated contrast material to weight-based dosing for contrast-enhanced abdominopelvic CT.

Their study, online December 22 in the Journal of the American College of Radiology, is based on data from more than 6,700 patients undergoing the procedure over two years at one medical center. The team collected data about the patients' height and weight within six months of a contrast-enhanced CT of the abdomen, pelvis, or both.

They excluded CT angiograms of the abdominal aorta and urinary tract CTs because those exams relied on different contrast-material dosing strategies.

Patient height, weight, lean body weight and body surface area were used to compare 26 volume- and weight-based dosing strategies to fixed volumes: 125 mL 300 mg of iodine (mgI)/mL for routine CT; and 125 mL 370 mgI/mL for multiphasic CT (single-energy, 120 peak kilovoltage (kVp)).

Overall, 91% of patients had routine CT. Converting to lower-volume, higher-concentration contrast material saved the most: a fixed-volume 100 mL 370 mgI/mL led to $132,577 in savings with preserved iodine dose for routine CT (37,500 mgI vs 37,000 mgI).

The predicted mean savings of all weight-based iodine-content dosing strategies (mgI/kg) with the same maximum contrast-material volume (125 mL) ranged from $4,053 to $116,076 in the study population and from $1 to $17 per strategy per patient. All sensitivity analysis showed similar trends.

"We were surprised to learn the magnitude of cost savings that could be realized if small changes were made to a handful of imaging protocols. We had always thought that the differences in cost would be modest, but they are not," said Dr. Davenport. "We would encourage all practices with an interest in maximizing value to re-examine the details of how they deliver care - they, too, might be surprised at what they find!"

He added, "There is extreme variation in how health systems choose to dose contrast material for the exact same types of CT examinations, which leads to waste and inconsistent utilization."

Dr. Nicole Hindman, an associate professor of radiology at New York University School of Medicine in New York City, welcomed the findings.

"Many radiologic practices have long-established protocols regarding contrast dosing, which have not been questioned for several years," she told Reuters Health by email. "This is a nice look at the various practices between institutions that rigorously reviews different CT dosing strategies and looks at outcome and cost."

"Overall, this is an excellent study with renewed attention to a CT practice that is overdue for re-analysis," she said.

Dr. Satinder P. Singh, chief of cardiopulmonary radiology at the University of Alabama at Birmingham, said the most important finding of this study is the ability to decrease contrast dose and cost without compromising quality.

"Although the adverse effects of contrast in relation to contrast dose is not clear, I think it is still better to use as little contrast as possible to decrease its adverse effects, particularly on the kidneys," said Dr. Singh, who also was not involved in the study.

"With advances in CT technology, the latest-generation scanners are very fast, which allows further contrast dose reduction," he told Reuters Health by email.

"One of the challenges of the fee-for-service payment model is that reducing material costs does not always translate into financial savings. In fact, such reductions often are financially harmful, creating a disincentive for health systems to pursue them," Dr. Singh pointed out.

SOURCE: http://bit.ly/2kiqKeD

J Am Coll Radiol 2016.