ISSN: 1524-4628 Copyright © 2009 American Heart Association. All rights reserved. Print ISSN: 0039-2499. Online Stroke is published by the American Heart Association. 7272 Greenville Avenue, Dallas, TX 72514 DOI: 10.1161/STROKEAHA.108.539528 2009 40 1973-1979 originally published online Apr 9, 2009 Stroke behalf of the SIVMS Steering Committee Clare E. Miller, Zahidul Quayyum, Paul McNamee, Rustam Al-Shahi Salman and on Population-Based Study Economic Burden of Intracranial Vascular Malformations in Adults: Prospective http://stroke.ahajournals.org/cgi/content/full/40/6/1973 located on the World Wide Web at: The online version of this article, along with updated information and services, is http://www.lww.com/reprints Reprints: Information about reprints can be found online at journalpermissions@lww.com 410-528-8550. E-mail: Fax: Kluwer Health, 351 West Camden Street, Baltimore, MD 21202-2436. Phone: 410-528-4050. Permissions: Permissions & Rights Desk, Lippincott Williams & Wilkins, a division of Wolters http://stroke.ahajournals.org/subscriptions/ Subscriptions: Information about subscribing to Stroke is online at at UNIVERSITEIT UTRECHT on May 25, 2011 stroke.ahajournals.org Downloaded from

Can$33 022 versus Can$26 085 in a Canadian study consid- ering both healthcare costs and lost productivity [1995]).9,10 Per-person lifetime healthcare costs for “operable” AVMs have been estimated using a decision analysis model comparing observation alone ($33 138) with surgery embolization ($37 484), and a policy of surgery for large- and medium-sized lesions and radiotherapy for small ( 3 cm) AVMs ($32 138 1991–1995).11 Therefore, we sought to estimate the short-term economic burden attributable to all new AVM and CM diagnoses in a prospective population-based cohort study of adults with IVMs,12,13 with a focus on direct healthcare costs and lost productivity. We intended to address the hypotheses that: presentation with hemorrhage confers higher overall (health- care and productivity) costs than nonhemorrhagic presenta- tion adults aged 65 years incur higher overall costs than those aged 65 years adults receiving interventional treat- ment incur higher overall costs than those who do not AVMs incur greater overall costs than CMs and AVMs with a small nidus size ( 3 cm maximum diameter) incur higher overall costs than those with a larger nidus size. Methods Scottish Intracranial Vascular Malformation Study The Scottish Intracranial Vascular Malformation Study (SIVMS) is a prospective population-based cohort study based on an anonymized extract of data from the Scottish Audit of Intracranial Vascular Malformations (SAIVMs, www.saivms.scot.nhs.uk), which identi- fied Scottish residents aged 16 years at the time they were first diagnosed with any type of IVM in the years 1999 to 2003.12 SAIVMs uses multiple overlapping sources of case ascertainment to identify adults, who are deemed to be incident in the year of their IVM’s definite radiological or pathological diagnosis, and on whom follow-up starts on the date of the clinical presentation that eventu- ally led to the diagnosis being made. Those who do not opt out of medical records surveillance and annual postal questionnaires are followed up on an annual basis by a questionnaire sent to their general (family) practitioner. Participants who opt in then complete annual postal health-related quality-of-life questionnaires. This sub- study included every adult in SIVMS during the years 1999 to 2003 with a definite diagnosis of an AVM or CM. At the time of this analysis in 2007, a maximum of 3 years’ follow-up data were available for the last adult detected in 2003, so we restricted our analyses to data accrued over the first 3 years after every adult’s initial presentation. Healthcare Costs We quantified healthcare costs using information obtained from medical records surveillance and national estimates of itemized healthcare costs for the tax year 2005 to 2006.14–16 Unfortunately, detailed electronic prescription records held by general practitioners were unavailable, so we did not include costs of pharmaceuticals (in particular, antiepileptic drugs). Inpatient Stays For every inpatient stay attributable to an adult’s IVM, we extracted information on length of stay (days) and the responsible specialty (or specialties). We estimated the cost of each inpatient episode using daily costs provided by the Information Services Division (ISD), which are specific to specialty and healthboard.14 We attributed admissions to intensive care units and neurosurgical, neurological, and rehabilitation wards to the healthboard of the neuroscience center at which the adult had been managed (Greater Glasgow, Lothian, Grampian, or Tayside), whereas we attributed admissions to any other specialty to the healthboard where the adult resided. Outpatient Appointments We estimated the cost of hospital outpatient appointments using a 3-year quantification of the total number of attended and unattended appointments documented in each adult’s medical records and the average cost of a neurology/neurosurgery appointment (£202.50).14 Interventions and Neuroimaging Costs of computed tomography (£93) and MRI (£150) were esti- mated from ISD’s Costs Book,14 whereas the procedure code corresponding to cerebral catheter angiography (“Diagnostic radiolo- gy–arteries or lymphatics”) was priced in the Scottish National Tariff Project (£1313).15 We obtained costs of endovascular embolization and aneurysm coiling (£1765) and linear accelerator stereotactic radiotherapy (£11 698) from the Scottish National Tariff Project,15 but because Gamma Knife stereotactic radiotherapy was only per- formed at the National Center for Stereotactic Radiosurgery in Sheffield, England, this was assigned an English reference cost (£8,040).16 In Scotland, the costs of neurosurgical theater time, materials, and anesthesia are incorporated into the inpatient costs calculated by ISD.14 Costs of Lost Productivity We calculated costs of lost productivity using national average weekly gross wage rates published by the Equal Opportunities Commission for Scotland17 (full-time [ 38 hours per week] £522.90 for men and £423.80 for women, part-time [ 38 hours per week] £375.50 for men and £319.40 for women), to estimate unearned income attributable to the loss of employment, or death within 3 years of each adult’s presentation. We determined employment status before and after the clinical presentation that led to IVM diagnosis, using a questionnaire sent in 2007 to living adults who had opted in to completing postal questionnaires. If a respondent had lost full- or part-time employment, the productivity loss was assumed to start on the day after presentation and to continue until the end of the third year of follow-up. We estimated the working patterns of those to whom we were unable to send questionnaires or from whom we did not receive responses, by assuming that they had the same employment patterns as those of the respondents. We tested for bias in the questionnaire-based data by comparing the characteristics of questionnaire respondents and nonrespondents. Statistical Analysis We used SPSS (Statistical Package for the Social Sciences [version 13]) and Microsoft Access and Excel for data management and analysis. We used parametric statistics when data obeyed a normal distribution and nonparametric statistics when they did not (Mann– Whitney U tests unless otherwise specified). Because of smaller sample size and the large proportion of adults who were unemployed at presentation, we used the mean as a measure of central tendency when reporting cost of lost productivity. We subdivided healthcare costs into 3 major subgroups (age or 65 years, hemorrhagic or nonhemorrhagic presentation, and whether or not interventional treatment was used), and subdivided costs of lost productivity into the latter 2 subgroups because these were likely to be the major influences on employment in adults of working age. Ethical Approval The Multicenter Research Ethics Committee for Scotland approved SIVMS (MREC 98/0/48). Results 369 adult Scottish residents were first diagnosed with a definite AVM (n 229) or CM (n 140) during 1999 to 2003. The median age at presentation was 45 years, 51% were male, and follow-up was complete until 3 years after presentation for all 328 who remained alive, and until death for the 41 who died within 3 years of presentation. Twenty-eight people died during the first year of follow-up, 5 died during the second 1974 Stroke June 2009 at UNIVERSITEIT UTRECHT on May 25, 2011 stroke.ahajournals.org Downloaded from