Using a simple, non-invasive test like a bone density scan to determine the future risk of cardiovascular disease would make sense if such a test was accurate and led to actions that could alter that risk. Unfortunately, the release on the study summarized here is lacking in details needed to gain a good understanding of how and when such a test would be used.
The suggestion of a linkage between osteoporosis and cardiovascular disease has been the topic of research for a number of years. Additional data supporting this linkage would add to our understanding. Because bone density is a non-invasive and widely available test, any suggestion that the test adds important information at the time must be appropriately conveyed in news reports. If such a test could also determine cardiovascular risk, then a patient might have twice as many reasons for it to be done. Because all tests, however, have the risks of false negatives and positives, as well as the potential for overdiagnosis and the future testing and unnecessary treatment it might cause, there is rightly a very high bar that needs to be cleared before subjecting whole populations to such a test. This news release contains almost none of the important bits of information needed to make an informed decision about this test.
The cost of a bone density scan is not mentioned and this is an important omission. Cardiovascular risk is currently assessed based on the epidemiological data from the Framingham Heart Study. The Framingham Cardiovascular Risk Calculator is based on these data and provides an easily obtained validated 10-year risk assessment. The only tests required are a blood test for total and HDL cholesterol (at a cost of $30-$40).
The US Preventive Services Task Force recommends screening for the presence of osteoporosis in women over age 65 years based on a cost-benefit assessment for that disorder. That means the cost of the screening is offset by the clinical benefits obtained. The use of a bone density scan to identify cardiovascular disease, especially in women under the age of 65 specifically for the diagnosis of osteoporosis and cardiovascular disease is a separate issue. While the cost of a bone densit scan is roughly $150-250 and still relatively low compared to other type of scans, it exceeds the cost of a total cholesterol and HDL cholesterol blood test. Unless and until the use of a bone density scan has been shown to provide more precise information, the cost could be viewed as excessive.
The proposed benefit is to find people at increased risk of heart disease with a bone density scan and treat them.
One of the authors is quoted:
“We found that that the presence of calcifications increased the likelihood of having cardiovascular disease such as heart attacks, and even the likelihood of cardiovascular deaths and mortality in general.”
However, the release doesn’t provide numbers that put the presumed benefit in context.
No harms were mentioned.
A bone density scan is a non-invasive and safe test, but the news release is silent on the issue of harms from false-positive or false-negative results — either of which could lead to over- or under-treatment.
The release does not provide an adequate amount of information to determine the quality of the evidence. The reader is told only that there were 1,000 older women (no defined age group), nothing is mentioned about their baseline risk factors and they were followed for 15 years for “the occurrence of cardiovascular disease,” which is not defined.
Importantly, the release does not explain how the information from the scan compares to that provided by already-recommended cardiovascular screenings, or whether it would lead to changes in treatment for anyone who is scanned.
There was no disease mongering.
There are no details in the release about how the authors of this research may or may not be tied to the bone density testing industry. But the published report makes it clear that they have ties to Hologic, which makes bone density testing machines:
Dr. Wilson is an employee of Hologic Inc. and reports personal fees, non-financial support and other from Hologic, Inc., during the conduct of the study; personal fees and other from Hologic, Inc., outside the submitted work; In addition, Dr. Wilson has multiple densitometer imaging and reporting patents which may be relevant, US and worldwide, both pending and issued owned by Hologic, Inc.
These are the kinds of financial ties that should always be disclosed in news releases.
As we noted previously, the Framingham Cardiovascular Risk Calculator is commonly used to assess the 10-year risk of a cardiovascular event and guide related treatment. The release does not mention this tool or how the results of bone density scanning would compare or improve upon it.
The release notes that bone density scanning is routinely used to diagnose osteoporosis and presumably it is widely available. What is not clear is whether bone density scanning to determine the degree of aortic calcification is generally available.
As we noted earlier, a link between bone density and cardiovascular disease has been explored for a number of years.
Banks, L.M., Lees, B., MacSweeney, J.E. and Stevenson, J.C., 1994. Effect of degenerative spinal and aortic calcification on bone density measurements in post‐menopausal women: links between osteoporosis and cardiovascular disease?. European journal of clinical investigation, 24(12), pp.813-817.
However, this may be the first use bone density scanning machines to explore the issue. Previous studies have used computed tomography (CT) scanners.
The language seems appropriate.