Should We Screen for Familial Intracranial Aneurysm?
1999; Lippincott Williams & Wilkins; Volume: 30; Issue: 10 Linguagem: Inglês
10.1161/01.str.30.10.2238g
ISSN1524-4628
AutoresPhil White, Kenneth W. Lindsay, E. Teasdale, Graham M. Teasdale, Joanna M. Wardlaw,
Tópico(s)Moyamoya disease diagnosis and treatment
ResumoHomeStrokeVol. 30, No. 10Should We Screen for Familial Intracranial Aneurysm? Free AccessOtherPDF/EPUBAboutView PDFView EPUBSections ToolsAdd to favoritesDownload citationsTrack citationsPermissions ShareShare onFacebookTwitterLinked InMendeleyRedditDiggEmail Jump toFree AccessOtherPDF/EPUBShould We Screen for Familial Intracranial Aneurysm? P.M. White, K.W. Lindsay, E. Teasdale and G.M. Teasdale J.M. Wardlaw P.M. WhiteP.M. White Departments of Neurosurgery and Neuroradiology, Institute of Neurological Sciences, Southern General Hospital, Glasgow, UK , K.W. LindsayK.W. Lindsay Departments of Neurosurgery and Neuroradiology, Institute of Neurological Sciences, Southern General Hospital, Glasgow, UK , E. TeasdaleE. Teasdale Departments of Neurosurgery and Neuroradiology, Institute of Neurological Sciences, Southern General Hospital, Glasgow, UK and G.M. TeasdaleG.M. Teasdale Departments of Neurosurgery and Neuroradiology, Institute of Neurological Sciences, Southern General Hospital, Glasgow, UK J.M. WardlawJ.M. Wardlaw Department of Clinical Neurosciences, Western General Hospital, Edinburgh, UK Originally published1 Oct 1999https://doi.org/10.1161/01.STR.30.10.2238gStroke. 1999;30:2238–2248To the Editor:The recent article by Crawley et al1 understates the increasing case against screening for familial intracranial aneurysms by overestimating the risk of aneurysm rupture and the accuracy of MR angiography (MRA) in a screening context, as well as underestimating the costs and risks of screening.The calculations of Crawley et al are based on an annual rupture risk of 0.4% to 1.5%.2 This figure is derived from a systematic review, but since then the International Study of Unruptured Intracranial Aneurysms,3 the largest study of unruptured aneurysms to date, found an annual rupture risk of only 0.05% for aneurysms 10 mm (or aneurysms in patients with a previous aneurysmal subarachnoid hemorrhage). The figure of 0.05% should be regarded as the more applicable to screening for aneurysms in asymptomatic relatives of subarachnoid haemorrhage patients.The value of MRA as a screening tool for the detection of intracranial aneurysms is still controversial, and the sensitivity and specificity of 90% quoted may be optimistic. We have systematically reviewed the world literature and identified 20 prospective "blinded reader" studies (of ≥10 subjects) comparing MRA with digital subtraction angiography and published between 1988 and 1997 that met quality criteria.4 The sensitivity of MRA ranged from 56% to 97% (median 88%) and specificity from 75% to 100% (median 95%), although not all papers provided sufficient data to calculate specificity. However, most intracranial aneurysms detected by a screening program would be <10 mm in size and more than a third would be <5 mm.5 MRA is much less accurate for small aneurysms ( 50% (and it was 10% in the remaining study), whereas a very low prevalence would be expected in a screening context. While it had been thought that prevalence did not influence sensitivity or specificity,7 more recent evidence indicates that a high disease prevalence leads to an increase in the calculated sensitivity and specificity of a diagnostic test.8 Therefore, if MRA is used as a screening tool in a low-prevalence population, the sensitivity will be less, possibly much less, than 90%.The costs of screening may be significantly higher than those used in the model. The quoted cost for MRA of $290 (∈274) is conservative. For a full screening study incorporating MRI of the brain, MRA plus targeted maximum intensity projection reconstructions and reported by a neuroradiologist, a figure approaching $450 (∈425) is more realistic. No evidence is quoted to support the assertion that screening would need to be repeated at least every 10 years. This is a very long time interval, and de novo intracranial aneurysm formation and rupture within 3 years has been observed in familial intracranial aneurysms.9It is also important not to understate the risk of surgery for an unruptured intracranial aneurysm. The estimate of death or dependence of 8% used by Crawley et al excludes less-severe morbidity of 5.5%.10 The prospective International Study of Unruptured Intracranial Aaneurysms data give the even higher rate for combined morbidity and mortality of 15.8%.3 People identified through a screening program for familial asymptomatic unruptured aneurysms would, in general, be healthy, therefore all morbidity after surgery should be included in the cost-benefit analysis of screening. There is a case for taking into account the benefit from reduction of anxiety from screening, but the effect of this has not been established.The omission of coiling of aneurysms is disappointing. Even though data on the risks and benefits of coiling are more limited, it would have been a useful inclusion in the model for comparison with an earlier study on this subject.11The available evidence indicates that the case against routine screening for familial intracranial aneurysms is stronger than that stated by Crawley et al. One way forward may be to identify which individuals within an affected family are at most risk. Although risk factors such as female sex, smoking, and heavy alcohol intake are recognized, more information is needed on the genetic basis and patterns of inheritance of familial intracranial aneurysms and subarachnoid hemorrhage. References 1 Crawley F, Clifton A, Brown MM. Should we screen for familial intracranial aneurysm? Stroke.1999; 30:312–316.CrossrefMedlineGoogle Scholar2 Rinkel GJE, Djibuti M, Algra A, van Gijn J. Prevalence and risk of rupture of intracranial aneurysms: a systematic review. Stroke.1998; 29:251–256.CrossrefMedlineGoogle Scholar3 International Study of Unruptured Intracranial Aneurysms (ISUIA) Investigators. Hemorrhage rates in patients with unruptured intracranial aneurysms. Stroke.1998; 29:273. Abstract.Google Scholar4 White PM, Wardlaw JM. How reliable is the non-invasive imaging of intracranial aneurysms? An objective assessment of the quality of the published literature. Cerebrovasc Dis. 1999;9(suppl 1):51. Abstract.Google Scholar5 Kojima M, Nagasawa S, Lee YE, Takeichi Y, Tsuda E, and Mabuchi N. Asymptomatic familial cerebral aneurysms. Neuroimaging Clin North Am.1998; 43:776–781.Google Scholar6 Korogi Y, Takahashi M, Mabuchi N, Nakagawa T, Fujiwara S, Horikawa Y. Intracranial aneurysms: diagnostic accuracy of MR angiography with evaluation of maximum intensity projection and source images. Radiology.1996; 199:199–207.CrossrefMedlineGoogle Scholar7 Sackett DL, Haynes RB, Guyatt GH, Tugwell P. Clinical Epidemiology: A Basic Science for Clinical Medicine. Boston, Mass: Little, Brown & Co; 1987:69–152.Google Scholar8 Brenner H, Gefeller O. Variation of sensitivity, specificity, likelihood ratios and predictive values with disease prevalence. Stat Med.1997; 16:981–991.CrossrefMedlineGoogle Scholar9 Ronkainen A, Puranen M, Hernesniemi JA, Vanninen R, Partanen PLK, Saari JT. Intracranial aneurysms: MR angiographic screening in 400 asymptomatic individuals with increased familial risk. Radiology.1995; 195:35–40.CrossrefMedlineGoogle Scholar10 Raaymakers TWM, Rinkel GJE, Limburg M, Algra A. Mortality and morbidity of surgery for unruptured intracranial aneurysms. Stroke.1998; 29:1531–1538.CrossrefMedlineGoogle Scholar11 Kallmes DF, Kallmes MH, Cloft HJ, Dion JE. Guglielmi detachable coil embolization for unruptured aneurysms in nonsurgical candidates: a cost-effectiveness exploration. AJNR Am J Neuroradiol.1998; 19:167–176.MedlineGoogle ScholarstrokeahaStrokeStrokeStroke0039-24991524-4628Lippincott Williams & WilkinsResponseBrown Martin M., FRCP, Crawley Francesca, MRCP, and Clifton Andrew, FRCR101999cerebral aneurysmscreeningWe thank White et al for their letter supporting our conclusionsR1 that screening for aneurysms is not justified in asymptomatic patients with a family history of subarachnoid hemorrhage. The fact that White et al believe we understated the case against screening while othersR2 have criticized our model as overstating the case suggests that we got the balance about right at the time we wrote our article. In our model we deliberately chose conservative figures to avoid any possibility of bias against screening. However, many of the figures quoted by White et al were not available when we submitted our original article and we agree that the new data further increase the case against routine screening. Previous Back to top Next FiguresReferencesRelatedDetails October 1999Vol 30, Issue 10Article InformationMetrics Download: 47 Copyright © 1999 by American Heart Associationhttps://doi.org/10.1161/01.STR.30.10.2238g Originally publishedOctober 1, 1999 Keywordscerebral aneurysmscreeningPDF download Advertisement
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