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Neurology Today:
doi: 10.1097/01.NT.0000383488.86191.c7
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Screening for Familial Aneurysms Every Seven Years Is Found Cost‐Effective

FITZGERALD, SUSAN

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ARTICLE IN BRIEF

Using a statistical model based on data on real patients who had been screened or not screened for familial intracranial aneurysms, Dutch investigators found that screening at seven-year intervals was most cost-effective.

The most cost-effective approach to screen for aneurysms in patients who have two or more first-degree relatives with a history of subarachnoid hemorrhage (SAH) is to do an MRA every seven years throughout most of their adult life, according to Dutch investigators who reported their findings in the May 25 issue of Neurology.

People with a close family history of SAH are at increased risk for aneurysm formation and rupture, but medical opinions vary on how often screening should be done to look for potential problems.

For this study, researchers at the University Medical Centre Utrecht in the Netherlands, used statistical modeling, not patients' records, to look at what strategy is most cost-effective.

“The current recommendations are that screening should be considered on an individual basis for all persons with two or more first-degree relatives with SAH,” the study's lead author, A. Stijntje E. Bor, MD, told Neurology Today. “According to our study, any screening strategy will be cost-effective, and the optimal screening strategy would be to screen every seven years, from age 20 to 80.”

But screening at seven-year intervals might not sit well with US patients and doctors, who are used to a health care system where the ready availability of technology and access to specialists have made all sorts of medical screening seem almost routine, experts not involved with the study told Neurology Today.

Under the health care reform legislation recently signed into law, the federal government is to step up funding for “comparative-effectiveness research” to identify which treatments work best, but even the mere mention of the research sparked some criticism that reform efforts will lead to medical rationing. Indeed, that was the fodder for much outcry last November when a federal task force said that most women in their 40s should stop getting annual mammograms and that most women over age 50 should only get screened every two years. The panel ended up qualifying some of its initial statements.

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CONSIDER INDIVIDUAL DIFFERENCES

Louis R. Caplan, MD, a professor of neurology at Harvard Medical School, said that studies looking at the cost-effectiveness of screening don't take into consideration the many varied circumstances of individual patients and he worries such research could be used by insurance payers to deny coverage.

“Studying large groups to see if screening pays off economically is not the way to go,” Dr. Caplan told Neurology Today. “If you have an aneurysm you don't want to wait five years to be tested again, because you're thinking you want to see your grandchild grow up.”

Dr. Bor said his group wanted to look at the financial side of screening because “cost-effectiveness is often considered when implementing a new screening tool, and can tip the scale toward implementing or rejecting the tool.”

The investigators relied on a statistical model to examine the cost-effectiveness of SAH screening because it would be difficult to answer the same question using a randomized-controlled trial (RCT).

“As familial SAH is rare, and the risk of aneurysm development and rupture is a continuous risk during the total lifespan of patients, assessment of the optimal screening strategy in an RCT would take decades of follow-up in a research population that is difficult to acquire,” they wrote.

“In addition to these difficulties, an RCT with ‘natural history’ as the basic strategy of intervention and ‘screening’ as an alternate strategy of intervention seems problematic, because most individuals with two or more relatives with SAH ask for screening, and are unwilling to await the natural history. When an RCT is not feasible, a simulation model may provide a reasonable alternate research method.”

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STUDY METHODOLOGY

The researchers searched the medical literature for data on real patients and then used the findings to build a statistical model to compare the cost-effectiveness of screening to no screening for familial intracranial aneurysms. The model allowed them to start screening at ages 20, 30, or 40 and to end screening at ages 60, 70, or 80.

The researchers also considered different screening intervals, including every two, three, five, seven, 10, and 15 years. Patients progressed in cycles of one year through the model, all starting at age 15 as “healthy without aneurysm.” The model allowed for different follow-up states, including healthy without aneurysm, healthy with aneurysm, healthy with small known aneurysm, disabled, or dead. Patients could become disabled or die because of SAH, complications of digital subtraction angiography (DSA), or complications of preventive aneurysm treatment.

Figure. DR. LOUIS R....
Figure. DR. LOUIS R....
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In the statistical model, screening consisted of MRA, followed by DSA for confirmation if a problem was detected. Aneurysms were treated either with clipping or coiling. If the aneurysm was considered too small to treat, the patient received follow-up screening every two years until the aneurysm either enlarged or ruptured. The researchers used data from previous studies to set the rates at which aneurysms would be detected or rupture over time. They noted in their report that the 10-year risk of SAH in people with a family history has been estimated to be 7 percent, while the lifetime risk could be as large as 26 percent.

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WHAT PAYS OFF?

The researchers used data from the Dutch health care system to determine the cost of the various approaches and then calculated “quality-adjusted life years,” a measure used by researchers to consider if the cost versus benefits of a screening tool or treatment falls within an acceptable range for a given country. Those screenings that ruled out an aneurysm were considered to boost quality of life, while screenings that found small untreatable aneurysms were considered to have a negative psychological impact for a short time.

“We found screening for intracranial aneurysms in individuals with two or more first-degree relatives with SAH to be cost-effective, irrespective of the interval of screening,” they concluded, though doing an MRA every seven years between ages 20 to 80 was best.

“Although we found that the cost-effectiveness of screening every two years may still be acceptable, screening this often may put a significant burden on the patient and may therefore lead to early abandonment of this screening strategy by patient and doctor,” they wrote.

Dr. Bor said his team also calculated cost-benefits using US data and found that screening in seven-year intervals “would yield one additional quality-adjusted life-year at an additional cost of $10,729, compared with a no-screening strategy.”

The researchers could not say whether the same screening approach would be warranted for patients who have only one relative with a history of SAH.

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IS THE MODEL REALITY-BASED?

Dr. Caplan said that while he respected the body of aneurysm research done by the Dutch group, he thought this particular cost-effectiveness study was of limited value to US physicians because the health care system here is structured differently than that in the Netherlands. He said the statistical model also could not account for all of the many variables that exist with patients — for instance, it didn't consider added risk factors for aneurysm development and rupture, such as smoking, hypertension and excessive alcohol use.

Dr. Caplan noted that it was impossible to measure the very real anxiety patients often feel when they know they have a small aneurysm that needs to be watched.“There are a lot of variables that go into deciding how often to screen,” he said, and advances in screening methods have made it far less risky to keep an eye on patients.

But S. Claiborne Johnston, MD, professor of neurology and epidemiology and director of the Clinical and Translational Science Institute at the University of California-San Francisco, said there is value in doing such cost effectiveness analysis (CEA).

“I think dismissing cost effectiveness analysis because it might lead to rationing is misguided and shows just how effective the pharmaceutical and device industries are in promoting their messages,” he said. “As a society, we can no longer afford to waste health care dollars. CEA is a tool that helps us to understand which interventions are valuable and which are expensive. Why turn our back on these kinds of data?”

Dr. Johnston added, however, that CEA is notoriously soft. “It is based on assumptions and can be fudged,” he said. “However, if done well, it gives you a sense of the value of interventions and the range of uncertainty. Without this, it's complete guess work.”

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REFERENCE

• Bor ASE, Koffijberg H, Rikel GJE, et al. Optimal screening strategy for familial intracranial aneurysms: A cost-effectiveness analysis. Neurology 2010; 74: 1671–1659.

©2010 American Academy of Neurology

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