The state of the art of medicine: Deciding on preventive screening tests after bleeding in the brain
David C. Spencer, MD
Doctors and medical researchers have made great strides in "evidence-basedmedicine." Evidence-based medicine means that doctors shoulduse the best research that is available to determine the bestway to treat patients. Currently, we don’t have all thenecessary facts to know the best way to treat patients in everysituation. Also, we need to know more about how to apply thefindings from research because everyone is different. In anarticle published in this issue of Neurology®, the authorslook at the facts about aneurysms (see below) and the dangersof bleeding in the brain.1 They examine the pros and cons of"screening." Screening refers to a test or tests that are doneto see whether a patient might have or might get a disease inthe future. They then think about how the decision to screenor not screen might affect patients’ quality of life.
WHAT IS A SUBARACHNOID HEMORRHAGE (SAH), AND WHAT IS AN ANEURYSM?
A subarachnoid hemorrhage (SAH) is a serious medical emergency.It occurs when a blood vessel (an artery) next to the brainbursts, causing sudden bleeding in and around the brain. Thistype of bleeding can happen for various reasons. A common reasonis the bursting of an aneurysm. An aneurysm forms when the wallof an artery weakens, stretches, and pouches out like a balloon.The thinned wall of an aneurysm can suddenly burst, causingdangerous bleeding. About four in 10 people will die from thiskind of bleeding.2 Those who live after this type of bleedingcan have problems.When a ruptured aneurysm is found, the aneurysmhas to be closed off or "clipped" by a surgeon to stop furtherbleeding. Even when this is done, those who live after havinga ruptured aneurysm are more likely to have another aneurysmcompared to others who have never had one. In fact, someonewho had an SAH from a ruptured aneurysm has about a 22 timesgreater chance of having another SAH than someone who has neverhad an SAH.3,4 An aneurysm can come back at the same place asthe original one, or form in a new place on another blood vessel.
The goal of this study is to understand whether it is helpfulto perform testing to look for another aneurysm or aneurysmsafter a person has had an SAH and a clipped aneurysm. The researcherslooked at several factors to decide whether testing was a goodidea. They looked at how much screening would cost, includingthe preventive surgeries that screening might lead to. Theycompared this with the medical costs associated with not screening(and maybe having more patients experience emergency SAH). Theylooked at the number of new aneurysms that could be found byscreening and treated. They estimated the number of new episodesof bleeding that screening could prevent. Finally, and importantly,they looked at not only changes in how long the patients wouldlive with or without screening, but also "quality-adjusted life-years"(QALYs), which means how good their life would be with or withoutthe screening.
The researchers looked at 610 people who had SAH, had an aneurysmtreated with surgical clipping, and had recovered enough tolive independently. Previous studies had shown that these peoplehave a higher chance of developing more aneurysms and havinga second SAH compared to people who had never had an SAH. Theresearchers looked at the effects of using a test called a CTA(computed tomography angiography), which takes a picture ofthe blood vessels in the brain, to screen for new aneurysmsin the study patients. They examined what the effects wouldbe of performing this test every 5 years to look for any signof a new aneurysm. If the CTA showed a new aneurysm, more testingfollowed. In this study, the screening CTA found new aneurysmsin 96 patients. Twenty-six people had further aneurysm treatment.The others had aneurysms that were too small to require treatmentbut that needed to be watched closely.
These findings were fed into a computer program that figuredout the consequences of choosing to screen or not screen. Theauthors estimated how many aneurysms could be found early andhow many SAHs were likely prevented. They used the computerprogram to calculate the effects of the screening process oncost, life expectancy, and quality of life.
The researchers found that screening of all patients with aprevious SAH was not cost-effective. Screening cost more thannot screening, even when considering that early detection andtreatment of aneurysms could save money by preventing SAH. Screeningonly extended life expectancy by a tiny amount on average, andit actually lowered the quality-of-life measure (QALYs). Thiswas because there were complications connected to screeningand preventive treatment that reduced quality-of-life measures.For example, an aneurysm found on CTA testing might lead tofurther testing such as an angiogram that can have complications,or to surgeries that can be more risky.
Other things that may predict a higher risk of aneurysm andrupture are high blood pressure and smoking. The authors foundthat if there were enough of these factors to double the chanceof another aneurysm, screening became cost-effective but stilldid not improve quality of life (QALYs). If patients had manyof these risk factors and were at very high risk (at least 4.5times more likely to have recurrences), then screening was agood idea because it lowered costs and improved quality of life(QALYs).
One of the most interesting findings of the study came whenthe researchers tried to estimate the effect of fear on qualityof life. Feelings such as fear are hard to quantify (put a numberon), but most of us know that a person’s quality of lifemight be worse if that person is always afraid of having anotherSAH. If the researchers considered even a small factor of reducedquality of life from this fear, then screening for recurrencesimproved quality-of-life measures even if patients did not haveadditional risk factors for SAH. This was because screeningprovided information to these patients that was either reassuring(there is no aneurysm) or that let them know what they weredealing with (there is a new aneurysm that needs preventivetreatment). This testing was also found to be fairly cost-effective.Looking at this issue was an important step; many studies ofthis type do not take such patient factors and their effectson quality of life into account.
WHAT SHOULD PATIENTS WHO HAVE HAD AN SAH FROM PREVIOUS ANEURYSM DO?
All patients in this situation can greatly benefit from quittingsmoking and keeping careful control of blood pressure. Theyshould talk with their doctor about the decision to screen fornew aneurysms. The effects of worry and fear should be consideredin the decision.
Other techniques to treat aneurysms besides surgical clippinghave been developed. Sometimes aneurysms can be closed off usingsmall coils. If other forms of treatment are used, the resultsof this analysis could be different. Also, this study was donein The Netherlands. The costs of screening and surgery are higherin the United States. Some of the testing thought to be cost-effectivein this study may not be cost-effective in US hospitals.
In the future, it will be important for researchers to use studymethods like those used for this project in other areas of investigation.In this study, the researchers chose to look at not just thenumbers of patients who have aneurysms detected by testing,or the numbers of patients who have recurrent SAH prevented,but also how the testing affected the years of life and thequality of those years of life in their patients. This is whatdoctors have tried to do for years in practicing the "art ofmedicine." This study shows that using scientific methods toask these question leads to interesting and useful results forpatients.
HOW THIS TYPE OF APPROACH IN RESEARCH MAY IMPROVE LIVES
The approach of looking at many issues surrounding disease screeningand treatment, including patients’ quality of life andsense of well-being, is likely to become even more importantin the future. For example, how often and in what form shouldscreening for breast cancer be done in a woman whose motherdied of breast cancer? What about in a woman with a newly discoveredgene that increases her risk for breast cancer? How much doesscreening cost? Is it a good use for limited health care dollars?Does the screening lead to a longer life, and are those yearsof better or worse quality of life? Does the testing reduceor increase the anxiety about a possible diagnosis? Should wescreen a frightened patient to improve quality of life for thatpatient, but not screen a patient with the same risk factorswho is not fearful of the future?
These and many other questions will need answers. More studiesare important because they give doctors the tools they needto help patients and to practice the science and "art" of medicine.
Wermer MJH, Koffijberg H, van der Schaaf IC, for the ASTRA Study Group. Effectiveness and costs of screening for aneurysms every 5 years after subarachnoid hemorrhage. Neurology 2008;70:2053–2062.[Abstract/Free Full Text]
Wermer MJH, Rinkel GJE, Greebe P, Albrecht KW, Dirven CM, Tulleken CA. Late recurrence of subarachnoid hemorrhage after treatment for ruptured aneurysms: patient characteristics and outcomes. Neurosurgery 2005;56:197–204.[Medline]
Tsutsumi K, Ueki K, Usui M, Kwak S, Kirino T. Risk of recurrent subarachnoid hemorrhage after complete obliteration of cerebral aneurysms. Stroke 1998;29:2511–2513.[Abstract/Free Full Text]
Wermer MJH, Greebe P, Algra A, Rinkel GJE. Incidence of recurrent subarachnoid hemorrhage after clipping for ruptured intracranial aneurysms. Stroke 2005;36:2394–2399.[Abstract/Free Full Text]
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