Heart
Cardiac Testing Puts Younger Adults at Radiation Risk
By Crystal Phend, Senior Staff Writer, MedPage Today
Published: July 07, 2010
Reviewed by Zalman S. Agus, MD; Emeritus Professor
University of Pennsylvania School of Medicine and
Dorothy Caputo, MA, RN, BC-ADM, CDE, Nurse Planner
Nearly one in 10 adults under age 65 gets radiation exposure from cardiac imaging over a given three-year period, researchers found in a population-based analysis.
The researchers analyzed administrative claims from a major U.S. insurer for more than 90,000 nonelderly adults who underwent at least one cardiac imaging procedure and, using a population-based annual rate, found 89.0 per 1,000 received an effective dose of ionizing radiation from the procedures greater than the background radiation from natural sources (more than 3 to 20 mSv per year).
Another 3.3 per 1,000 got cumulative annual doses above the upper limit for occupational exposure averaged over five years (20 mSv per year), Jersey Chen, MD, MPH, of Yale, and colleagues reported online in the Journal of the American College of Cardiology (JAAC).
Extrapolating these results to the U.S. population in the same age range suggested that 636,000 people would be at risk from high cumulative effective doses of ionizing radiation from cardiac imaging, which the researchers called "considerable." The public health and clinical implications aren't easy to determine since the cancer risk that comes with ionizing radiation is countered by the benefit of catching and treating potentially life-threatening cardiac illness, they noted.
But since cardiac imaging appeared to account for about 30% of the total annual exposure to radiation from medical testing overall, cardiologists bear particular responsibility for minimizing risk by selection of tests and optimal technical practices, Chen's group said.
An accompanying JAAC editorial agreed that these results should give cardiologists pause.
But Matthew J. Budoff, MD, and Mohit Gupta, MD, both of Harbor UCLA Medical Center in Torrance, Calif., cautioned in theeditorial "that the entire premise that radiation doses from medical testing causes cancers remains hypothetical."
Although ionizing radiation at high levels like atomic bomb exposure causes cancer and death, "the relationship between low-dose medical imaging and harm has never been established," they wrote in the editorial.
The researchers analyzed administrative claims from one of the largest private healthcare insurers, United Healthcare, for five major markets across the U.S. that had similar insurance characteristics.
This included all 952,420 adults ages 18 to 64 in Arizona, Dallas, Orlando, South Florida, and Wisconsin who were alive and continuously insured by the company from the beginning of 2005 to the end of 2007.
Overall, 9.5% of the insured adults ages 18 to 64 got at least one cardiac radiology procedure that exposed them to radiation over the three-year period for a population-based rate of rate of 60.3 per 1,000 enrollees each year.
Not surprisingly, older adults and men accounted for a larger proportion of the cardiac imaging procedures.
The rate in men was 10.5% compared with women's 8.5% (P<0.0001).
The proportion of individuals who had at least one procedure over the three-year period rose from 1.5% in those 18 to 34 years old to 20.9% in 55- to 64-year-olds.
Still, "our study demonstrates that there are sizable rates of radiation exposure for patients age 35 to 54 years, many of whom will likely live long enough for such long-term complications [as malignancy] to potentially develop," Chen's group wrote.
Alternative imaging modalities without ionizing radiation that provide similar clinical information for informed decision-making may be a better choice for these younger patients, the researchers suggested.
"For example, alternatives such as stress echocardiography or, in some cases, exercise testing alone without imaging could serve as alternatives to myocardial perfusion imaging scans," they wrote in JACC.
For those who got at least one cardiac imaging procedure using radiation, the mean cumulative effective dose over three years was 16.4 mSv. But the range peaked at 189.5 mSv.
Myocardial perfusion imaging was the most common of these procedures, accounting for 74% of the cumulative effective dose for the whole group.
Mirroring the increasing availability, 47.8% of cardiac imaging procedures were performed in physician offices; this proportion was higher for myocardial perfusion imaging (74.8%) and cardiac computed tomography studies (76.5%).
However, the JAAC editorialists argued that Chen's group used outdated radiation exposure figures significantly higher than current clinical practice, "and therefore their estimates of theoretical harm are consistently overstated."
Also, since natural background radiation rises from approximately 3 mSv per year at sea level to 7 mSv per year with elevation without a link to increased cancer rates in the U.S., "the simple linear no-threshold model of radiation exposure may be flawed," Budoff and Gupta wrote.
They concluded that it's time to "move beyond radiation models, with so many assumptions, to studies documenting the real risk (if any) to the cardiac patient."
Limitations of the study included the use of estimates of effective dose rather than a patient-specific measure to quantifying radiation doses, Chen and colleagues noted, and administrative data are "inherently limited" in determining the appropriate use of cardiac imaging procedures. Additionally, the data are restricted to five markets covered by one insurer and the use of radiologic cardiac imaging procedures may differ in other areas of the U.S. and with other insurers, they added.
Action Points
Source reference:
Chen J, et al "Cumulative exposure to ionizing radiation from diagnostic and therapeutic cardiac imaging procedures: A population-based analysis" J Am Coll Cardiol 2010; 56.
Additional source: Journal of the American College of Cardiology
Source reference:
Budoff MJ, Gupta M "Radiation exposure from cardiac imaging procedures: Do the risks outweigh the benefits?" J Am Coll Cardiol 2010; 56.
Source: Medpagetoday.com
LINK TO SOURCE
By Crystal Phend, Senior Staff Writer, MedPage Today
Published: July 07, 2010
Reviewed by Zalman S. Agus, MD; Emeritus Professor
University of Pennsylvania School of Medicine and
Dorothy Caputo, MA, RN, BC-ADM, CDE, Nurse Planner
Nearly one in 10 adults under age 65 gets radiation exposure from cardiac imaging over a given three-year period, researchers found in a population-based analysis.
The researchers analyzed administrative claims from a major U.S. insurer for more than 90,000 nonelderly adults who underwent at least one cardiac imaging procedure and, using a population-based annual rate, found 89.0 per 1,000 received an effective dose of ionizing radiation from the procedures greater than the background radiation from natural sources (more than 3 to 20 mSv per year).
Another 3.3 per 1,000 got cumulative annual doses above the upper limit for occupational exposure averaged over five years (20 mSv per year), Jersey Chen, MD, MPH, of Yale, and colleagues reported online in the Journal of the American College of Cardiology (JAAC).
Extrapolating these results to the U.S. population in the same age range suggested that 636,000 people would be at risk from high cumulative effective doses of ionizing radiation from cardiac imaging, which the researchers called "considerable." The public health and clinical implications aren't easy to determine since the cancer risk that comes with ionizing radiation is countered by the benefit of catching and treating potentially life-threatening cardiac illness, they noted.
But since cardiac imaging appeared to account for about 30% of the total annual exposure to radiation from medical testing overall, cardiologists bear particular responsibility for minimizing risk by selection of tests and optimal technical practices, Chen's group said.
An accompanying JAAC editorial agreed that these results should give cardiologists pause.
But Matthew J. Budoff, MD, and Mohit Gupta, MD, both of Harbor UCLA Medical Center in Torrance, Calif., cautioned in theeditorial "that the entire premise that radiation doses from medical testing causes cancers remains hypothetical."
Although ionizing radiation at high levels like atomic bomb exposure causes cancer and death, "the relationship between low-dose medical imaging and harm has never been established," they wrote in the editorial.
The researchers analyzed administrative claims from one of the largest private healthcare insurers, United Healthcare, for five major markets across the U.S. that had similar insurance characteristics.
This included all 952,420 adults ages 18 to 64 in Arizona, Dallas, Orlando, South Florida, and Wisconsin who were alive and continuously insured by the company from the beginning of 2005 to the end of 2007.
Overall, 9.5% of the insured adults ages 18 to 64 got at least one cardiac radiology procedure that exposed them to radiation over the three-year period for a population-based rate of rate of 60.3 per 1,000 enrollees each year.
Not surprisingly, older adults and men accounted for a larger proportion of the cardiac imaging procedures.
The rate in men was 10.5% compared with women's 8.5% (P<0.0001).
The proportion of individuals who had at least one procedure over the three-year period rose from 1.5% in those 18 to 34 years old to 20.9% in 55- to 64-year-olds.
Still, "our study demonstrates that there are sizable rates of radiation exposure for patients age 35 to 54 years, many of whom will likely live long enough for such long-term complications [as malignancy] to potentially develop," Chen's group wrote.
Alternative imaging modalities without ionizing radiation that provide similar clinical information for informed decision-making may be a better choice for these younger patients, the researchers suggested.
"For example, alternatives such as stress echocardiography or, in some cases, exercise testing alone without imaging could serve as alternatives to myocardial perfusion imaging scans," they wrote in JACC.
For those who got at least one cardiac imaging procedure using radiation, the mean cumulative effective dose over three years was 16.4 mSv. But the range peaked at 189.5 mSv.
Myocardial perfusion imaging was the most common of these procedures, accounting for 74% of the cumulative effective dose for the whole group.
Mirroring the increasing availability, 47.8% of cardiac imaging procedures were performed in physician offices; this proportion was higher for myocardial perfusion imaging (74.8%) and cardiac computed tomography studies (76.5%).
However, the JAAC editorialists argued that Chen's group used outdated radiation exposure figures significantly higher than current clinical practice, "and therefore their estimates of theoretical harm are consistently overstated."
Also, since natural background radiation rises from approximately 3 mSv per year at sea level to 7 mSv per year with elevation without a link to increased cancer rates in the U.S., "the simple linear no-threshold model of radiation exposure may be flawed," Budoff and Gupta wrote.
They concluded that it's time to "move beyond radiation models, with so many assumptions, to studies documenting the real risk (if any) to the cardiac patient."
Limitations of the study included the use of estimates of effective dose rather than a patient-specific measure to quantifying radiation doses, Chen and colleagues noted, and administrative data are "inherently limited" in determining the appropriate use of cardiac imaging procedures. Additionally, the data are restricted to five markets covered by one insurer and the use of radiologic cardiac imaging procedures may differ in other areas of the U.S. and with other insurers, they added.
Action Points
- Explain to interested patients that ionizing radiation carries long-term risks for cancer, which need to be balanced against the benefits in diagnosing and assisting in the treatment of cardiovascular disease.
- Note that the study used radiation exposure without direct correlation to hard endpoints, such as actual cancer incidence.
- Further note that the study data are based on estimated, not patient-specific, doses and that cardiac imaging procedures may differ in other areas of the U.S. covered by other insurers.
Source reference:
Chen J, et al "Cumulative exposure to ionizing radiation from diagnostic and therapeutic cardiac imaging procedures: A population-based analysis" J Am Coll Cardiol 2010; 56.
Additional source: Journal of the American College of Cardiology
Source reference:
Budoff MJ, Gupta M "Radiation exposure from cardiac imaging procedures: Do the risks outweigh the benefits?" J Am Coll Cardiol 2010; 56.
Source: Medpagetoday.com
LINK TO SOURCE