The average amount that Medicare spent on imaging for each beneficiary within two years of cancer diagnosis increased between 5.1% and 10.3% per year during the study period for cancer imaging of all types, according to researchers from Duke University School of Medicine in Durham, NC. That compares to growth of 1.8% to 4.6% per year in overall cancer expenses within the Medicare program. The lead author on the study is Michaela Dinan from the Duke Clinical Research Institute in Durham (JAMA, Vol. 303:16, pp. 1625-1631).
The researchers said they launched the study after noticing growth in imaging utilization on an anecdotal basis, according to study co-author Dr. Edward Patz Jr., professor of pharmacology and cancer biology in Duke's department of radiology.
"We are all concerned about cost and utilization in healthcare in general," Patz said. "We had seen what appear to be increases in imaging utilization and the question was: Is it really going up and what is the percentage of total cost care? And what do we know about imaging costs in oncology?"
Analyzing the data
The study cited statistics from the American Cancer Society (ACS), which found that cancer caused more than 500,000 deaths in the U.S. in 2008 and was responsible for some $228.1 billion in healthcare costs. Previous research also concluded that cancer-related expenditures are expected to grow faster than any other area of healthcare.
The researchers obtained administrative claims data for a 5% sample of Medicare beneficiaries from 1997 to 2008 from the U.S. Centers for Medicare and Medicaid Services (CMS). From those files, they tallied 100,954 incident cases of breast cancer, colorectal cancer, leukemia, lung cancer, non-Hodgkin's lymphoma, and prostate cancer from 1999 through 2006. The median age of cancer incidence was 76 years, and slightly more than half of the patients were men.
The researchers also added the number of imaging procedures per Medicare beneficiary based on the number of imaging claims in the two-year period after the onset of cancer. The claims were divided into eight categories: bone density studies, CT, echocardiography, MRI, nuclear medicine, PET, radiography, and ultrasound.
The mean number of imaging procedures per beneficiary during the two-year period varied substantially by modality and cancer type. Patients with lymphoma or lung cancer underwent the largest number of imaging procedures.
By 2006, the average patient with lung cancer had 11 conventional radiographs, six CT scans, one PET scan, a separate nuclear medicine test, one MRI exam, two echocardiograms, and an ultrasound -- all within two years of diagnosis.
The average patient with lymphoma in 2006 had eight conventional radiographs, six CT scans, one PET scan, one nuclear medicine test, an MRI exam, three echocardiograms, and three ultrasounds, also within two years of diagnosis.
The number of PET scans among all cancer patients increased, with a mean annual growth rate of 35.9% for lung cancer patients, 38.7% for lymphoma patients, and 53.6% for breast cancer patients. Conversely, there was an overall decline in nuclear medicine tests in lung cancer (-1.6%) and lymphoma (-3.1%) cases.
PET's rise in utilization, however, is "particularly noteworthy," the authors wrote.
Because of increased interest in and availability of PET, improved CMS reimbursement, and studies that show its efficacy in changing treatment for cancer patients, Patz said he and his colleagues were "not surprised" that the level of PET utilization started at a "very low level and has come up." Over the next 10 years, he said, PET's percentage growth is expected to flatten and reflect the trends in the other modalities.
As for PET's residual effect on the other modalities, Patz said changes "may not be reflected in all the imaging studies, although in cases such as lung cancer, if you do a PET, you don't have to do a bone scan. You have to look at not only the total cost, but also all the downstream consequences. Again [PET] could be enormously cost-effective; we just don't know how cost-effective. All we know is what the trends for imaging are."
Among other imaging modalities, there was increased use of bone density scans, ranging from 6.3% for colorectal cancer to 20.0% for prostate cancer. Echocardiograms also had increased use, from a low of 5.0% in lung cancer to a high of 7.8% for breast cancer.
MRI use increased by 4.4% for lymphoma to 11.5% for leukemia. Ultrasound had its lowest gain, 0.7%, for prostate cancer and greatest hike, 7.4%, for lymphoma. The use of CT increased among all cancer types except lymphoma (-0.9%), ranging from 4.5% for lung cancer to 7.6% for breast cancer and leukemia.
|Mean imaging procedure counts per beneficiary by cancer type
|Source: JAMA, April 28, 2010.
'What we expected'
"I think this is what we expected," Patz said. "As a clinical radiologist, I read films all the time. We had seen a significant increase in what we were doing in oncology patients. The question is how much impact is there, but we haven't been able to answer that question yet."
The use of conventional radiographs decreased or stayed the same on a percentage basis in each cancer category. However, x-ray remains the most frequently used imaging modality in terms of total scans for all cancer diagnoses. For example, radiographs were used to image and diagnose 24,178 lung cancer cases in the study sample in 2006, compared with 2,177 PET scans that same year.
Most patients (80% to 98%) received at least one conventional radiograph, with approximately 80% of patients with prostate cancer and 98% of patients with lung cancer receiving one or more radiographs.
The next step for the Duke research team is to explore utilization trends.
"With all the healthcare bills and healthcare costs, we need to understand utilization costs, so we can take it to the next level, which is to understand cost-effectiveness, where we are spending our money, does it make sense, or does it not make sense," Patz said. "In these scenarios, we can't just continue to propagate the belief that [imaging] earlier or more frequently is better. It may be [better], but we don't have the data right now. This is the first step in trying to understand some of the utilization in oncology."
By Wayne Forrest
AuntMinnie.com staff writer
April 27, 2010
Imaging utilization can vary widely for pediatric inpatients, April 23, 2010
Final answer on equipment use rate: 75% in 2011, March 26, 2010
Study offers more nuanced views of U.S. imaging use rates, March 22, 2010
PET use by nonrads growing rapidly, March 2, 2010
NEJM study: Imaging procedures, radiation growing, August 26, 2009
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