‘Surge’ in unnecessary CT scans significantly increases cancer risks

A single standard CT scan may increase the risk for fatal cancer in one of every 2,000 patients, according to FDA data.

Repeat or excessive exposure to ionizing radiation only increases cancer risk.

Earlier this year, Renee Y. Hsia, MD, MSc, FACEP, professor and director of health policy studies and attending physician at San Francisco General Hospital and Trauma Center at University of California, San Francisco, and colleagues assessed use of CT scans in California-based emergency departments. Their findings, published in Journal of Surgical Research, showed use of CT scans more than doubled for patients with nonserious injuries doubled from 2005 to 2013.

Diana L. Miglioretti

“The surge in the use of CT scans in a variety of settings and conditions has been well documented,” Hsia told HemOnc Today. “Our study looks at imaging from a different angle, mainly examining those with minor injuries, as those are a large proportion of visitors who come to the ED and are ultimately discharged home because they are not sick enough to be admitted to the hospital. We found that the proportion of patients receiving at least one CT scan during their ED visit more than doubled during our study period, which is very concerning.”

Risks vs. benefits

Hsia and colleagues pooled data from the California Office of Statewide Health Planning and Development to examine records of more than 8 million adult patient visits across 348 California hospitals.

All patients were discharged from the hospital after treatment for minor falls or low-impact car accidents.

The researchers determined the percentage of patients who underwent at least one CT scan increased from 3.51% in 2005 to 7.17% in 2013.

Hospitals considered to be high-level trauma centers were more likely than low-level centers to order CT scans (39% for level I or level II centers vs. 3% for low-level centers).

Predictors for CT included age 18 to 24 years, Medicare or self-pay patients, treatment at level I or level II trauma centers, and those who were injured during falls or motor vehicle collisions (P < .005 for all).

“The message for both patients and physicians is that there are long-term risks associated with radiation exposure and there may be situations where imaging is not definitively warranted or beneficial,” Hsia said in a press release. “We cannot conclusively say which cases should not involve imaging, since every patient and every circumstance is different, but given that it is getting easier and easier to get CT scans, we need to be cautious in weighing their risks and benefits.”

Alternative options

Previously published studies suggest one-third of CT scans are performed unnecessarily, according to Diana L. Miglioretti, PhD, dean’s professor in biostatistics in the department of public health sciences at UC Davis School of Medicine.

Miglioretti and colleagues conducted a modeling study to compare biennial mammography screening starting at age 50 years vs. annual screening beginning at age 40 years. Results showed biennial mammography from ages 50 to 74 years reduced the risk for radiation-induced breast cancer and breast cancer death by fivefold compared with annual screening from ages 40 to 74 years.

“It is important to remember that the risks associated with a single CT scan are quite low, so when there is a real medical need for a CT scan, the patient should, of course, do it. However, when applied in such large numbers, as we do today to millions of individuals, it causes a significant increase in cancer risk,” Miglioretti told HemOnc Today. “It is important to limit CT scans to only when medically necessary and there are no imaging test alternatives available.”

One example of an alternative test is the use of ultrasound as the first option for children who present with a possible appendicitis. Several well-documented studies suggest ultrasound is safe and cost-effective while also reducing radiation exposure, Miglioretti said.

Ultrasound also may be used as a first test for possible kidney stones.

“We need to look at other alternatives to CT scans in order to reduce radiation exposure in the population, and we need to work to identify standard protocols for CT dose parameters,” Miglioretti said.

Miglioretti is working with Rebecca Smith-Bindman, MD, professor in residence of radiology, epidemiology and biostatistics at University of California, San Francisco, to identify standard protocols that will lead to the lowest dose of radiation needed to have an interpretable image.

“Surprisingly, a lot of hospitals are not aware of the radiation doses they are using,” Miglioretti said. “We are providing hospitals with a report to show them how their doses compare to other hospitals. ... We held a meeting and brought radiologists and medical physicists from all of the University of California hospitals together and showed them how their doses compared with one another. This alone reduced their doses drastically, and we are now testing interventions like this in a larger number of hospitals. We need to work on alternative strategies whenever possible and, if a CT scan is necessary, then we need to make sure that we are using the lowest doses possible.”

Higher deductibles

The price of CT scans and other diagnostic imaging modalities can be substantial and deter individuals with high-deductible health care plans from undergoing necessary imaging, according to study results published earlier this year in Medical Care.

Kimberley Geissler, PhD, of the department of health promotion and policy at University of Massachusetts School of Public Health and Health Sciences, and colleagues at Boston University Questrom School of Business found that adults enrolled in high-deductible health plans underwent fewer imaging studies and had lower imaging spending than those in high-deductible plans.

The price and total costs of CT scans varied substantially due to several factors, including type of scan, quantity, location and type of insurance coverage.

“Spending on diagnostic imaging has grown rapidly in past decades, with high-value imaging providing for earlier and more accurate disease diagnoses,” Geissler told HemOnc Today. “However, low-value imaging use can harm patients, exposing them to unnecessary radiation — in the case of CT scans — and having downstream clinical and cost implications.”

Previous recommendations to slow the growth of diagnostic imaging to maximize high-value use primarily have assessed physician and insurer incentives. For this reason, Geissler and colleagues sought to examine whether patient incentives in the form of higher cost-sharing affected the use of imaging and, if so, whether they differentially reduced low-value or high-value use.

The researchers used a nationwide dataset of health insurance claims to analyze differences in the use of diagnostic imaging between patients enrolled in high-deductible health plans vs. other private insurance.

“Those with high-deductible health plans utilized significantly fewer imaging studies, and this difference was mostly due to whether or not an individual had any imaging,” Geissler said. “People in high-deductible health plans were significantly less likely to use any imaging, but once they had at least one imaging study, the number of studies conducted and associated payments were relatively similar. We also examined the use of low-value imaging tests and found that individuals with high-deductible health plans did not differentially reduce their use of low-value imaging tests versus all imaging.”

Data from a sub-analysis that assessed differences in reduced utilization by health status of high-deductible health plan enrollees suggested that enrollees of these types of health plans who were the least sick reduced imaging use by 9.2% vs. those with other insurance types.

“High-deductible health plan enrollees in the sickest group had reductions in use that were half this size,” Geissler said. “Based on spending levels in the sickest group, these are individuals who are likely to exceed the deductible with or without imaging use; therefore, the high deductible might not impact their decision-making as substantially as those with lower health care spending.”

Education needed

Experts agree that better patient awareness and education are key components to reducing imaging utilization.

“Although high-deductible health plans are associated with reduced imaging utilization and spending, they are blunt instruments that do not necessarily encourage physicians and patients to choose high-value care,” Geissler said. “Understanding the drivers of imaging use and exploring physician and patient incentives to reduce low-value care while maintaining patient access to high-value imaging is crucial.”

Patients — particularly parents whose children may need to undergo CT scans — need to make sure they take charge of their own care, Miglioretti said.

“If a patient is told that they need a CT scan, they should first ask if it is medically necessary and how will it change their medical care,” she said. “If the physician still says it is medically necessary ... they should go through with the scan. On an individual-patient level, the cancer risk is slight and the benefits outweigh the risk in most cases. But, again, we need to make sure that physicians are ordering these tests only when medically necessary. Parents should make sure protocols of lower radiation doses are utilized for children.”

Practitioners and patients alike need to be more aware of what appears to be a lower threshold to order imaging studies such as CT scans, Hsia said.

“Our hope is that, as people become more aware, there will be more caution exercised when making these decisions,” she said. “I also believe that shared decision-making — especially in these less severe cases — is very appropriate, and that patients should be involved in these decisions.” – by Jennifer Southall

For more information:

Kimberley Geissler, PhD, can be reached at University of Massachusetts School of Public Health and Health Sciences, 300 Massachusetts Ave., Amherst, MA 01003; email: kgeissler@umass.edu.

Renee Y. Hsia, MD, MSc, FACEP, can be reached at University of California, San Francisco,
., 1E21, San Francisco, CA 94110; email: renee.hsia@ucsf.edu.

Diana L. Miglioretti, PhD, can be reached at UC Davis School of Medicine, 1 Shields Ave., Med Sci 1C, Room 145, Davis, CA 95616; email: dmiglioretti@ucdavis.edu.

References:

Miglioretti DL, et al. Ann Intern Med. 2015;doi:10.7326/M15-1241.

Tong GE, et al. J Surg Res. 2015;doi:10.1016/j.jss.2015.11.046.

U.S. FDA. What are the radiation risks from CT? Available at: http://www.fda.gov/Radiation-EmittingProducts/RadiationEmittingProductsandProcedures/MedicalImaging/MedicalX-Rays/ucm115329.htm. Accessed on March 9, 2016.

Zheng S, et al. Med Care. 2016;doi:10.1097/MLR.0000000000000472.

Disclosure: Geissler, Hsia and Miglioretti report no relevant financial disclosures.