This Article Full Text Full Text (PDF) All Versions of this Article: 35/9/2041    most recent 01.STR.0000137605.48864.2fv1 Alert me when this article is cited Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Request Permissions Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Coull, A.J. Search for Related Content PubMed PubMed Citation Articles by Coull, A.J. Related Collections Acute Stroke Syndromes Related Article

(Stroke. 2004;35:2041.)
© 2004 American Heart Association, Inc.

Original Contributions

Direct Assessment of Completeness of Ascertainment in a Stroke Incidence Study

A.J. Coull, MRCP; L.E. Silver, MSc; L.M. Bull, RN; M.F. Giles, MRCP P.M. Rothwell, FRCP on behalf of the Oxford Vascular (OXVASC) Study

From the Stroke Prevention Research Unit, Department of Clinical Neurology, Radcliffe Infirmary, Oxford, UK.

Correspondence to Dr P.M. Rothwell, Stroke Prevention Research Unit, Department of Clinical Neurology, Radcliffe Infirmary, Woodstock Road, Oxford, OX2 6HE, UK. E-mail peter.rothwell{at}clneuro.ox.ac.uk

Background and Purpose— Validity of comparisons of stroke incidence between studies or time periods depends on the completeness of ascertainment. Ascertainment cannot be reliably assessed indirectly by statistical methods, such as capture–recapture. We report the first use of direct methods to determine the completeness of different ascertainment strategies in a population-based stroke incidence study (Oxford Vascular Study).

Methods— We assessed completeness of 2 different ascertainment strategies: the core methods common to most previous incidence studies and core plus supplementary methods used in some studies (including access to carotid and brain imaging referrals and assessment of patients referred as "transient ischemic attack" or "recurrent stroke"). We assessed completeness of ascertainment in 2 ways. First, we searched anonymized primary care electronic patient records of the whole study population (n=90 542). Second, we interviewed and followed-up a high-risk subset of our study population: all patients who had an acute coronary or peripheral vascular event or a related elective investigation or intervention.

Results— 126 strokes were ascertained by the core plus supplementary methods, of which only 108 were identified by the core methods alone. Only 2 additional incident strokes were identified by access to primary care electronic patient records of the whole study population. Assessment and follow-up of 1103 high-risk individuals (5.5% of our total study population aged older than 60 years) identified 16 incident strokes. However, all 16 had already been ascertained by the core plus supplementary methods.

Conclusions— The core methods of ascertainment used in some stroke incidence studies lead to significant underascertainment. However, direct assessment of ascertainment suggests that the supplementary methods used in recent studies can lead to near-complete ascertainment.

Key Words: epidemiology • incidence • stroke

Related Article:

Editorial Comment—Stroke Incidence Studies One Step Closer to the Elusive Gold Standard?

Valery L. Feigin and Kristie Carter
Stroke 2004 35: 2045-2047. [Extract] [Full Text] [PDF]

This article has been cited by other articles:

				A. Chandratheva, Z. Mehta, O. C. Geraghty, L. Marquardt, P. M. Rothwell, and On behalf of the Oxford Vascular Study Population-based study of risk and predictors of stroke in the first few hours after a TIA Neurology, June 2, 2009; 72(22): 1941 - 1947. [Abstract] [Full Text] [PDF]

				S. E. Sridharan, J.P. Unnikrishnan, S. Sukumaran, P.N. Sylaja, S. D. Nayak, P. S. Sarma, and K. Radhakrishnan Incidence, Types, Risk Factors, and Outcome of Stroke in a Developing Country: The Trivandrum Stroke Registry Stroke, April 1, 2009; 40(4): 1212 - 1218. [Abstract] [Full Text] [PDF]

				E. McFadden, R. Luben, N. Wareham, S. Bingham, and K.-T. Khaw Social Class, Risk Factors, and Stroke Incidence in Men and Women: A Prospective Study in the European Prospective Investigation Into Cancer in Norfolk Cohort Stroke, April 1, 2009; 40(4): 1070 - 1077. [Abstract] [Full Text] [PDF]

				C. Winward, C. Sackley, Z. Metha, and P. M. Rothwell A Population-Based Study of the Prevalence of Fatigue After Transient Ischemic Attack and Minor Stroke Stroke, March 1, 2009; 40(3): 757 - 761. [Abstract] [Full Text] [PDF]

				P. U. Heuschmann, A. P. Grieve, A. M. Toschke, A. G. Rudd, and C. D.A. Wolfe Ethnic Group Disparities in 10-Year Trends in Stroke Incidence and Vascular Risk Factors: The South London Stroke Register (SLSR) Stroke, August 1, 2008; 39(8): 2204 - 2210. [Abstract] [Full Text] [PDF]

				P. G. Surtees, N.W.J. Wainwright, R. N. Luben, N. J. Wareham, S. A. Bingham, and K.-T Khaw Psychological distress, major depressive disorder, and risk of stroke Neurology, March 4, 2008; 70(10): 788 - 794. [Abstract] [Full Text] [PDF]

				R. Luengo-Fernandez, A. M. Gray, and P. M. Rothwell Population-Based Study of Determinants of Initial Secondary Care Costs of Acute Stroke in the United Kingdom Stroke, October 1, 2006; 37(10): 2579 - 2587. [Abstract] [Full Text] [PDF]

				J. F Fairhead and P. M Rothwell Underinvestigation and undertreatment of carotid disease in elderly patients with transient ischaemic attack and stroke: comparative population based study BMJ, September 9, 2006; 333(7567): 525 - 527. [Abstract] [Full Text] [PDF]

				M. F. Giles, E. Flossman, and P. M. Rothwell Patient Behavior Immediately After Transient Ischemic Attack According to Clinical Characteristics, Perception of the Event, and Predicted Risk of Stroke Stroke, May 1, 2006; 37(5): 1254 - 1260. [Abstract] [Full Text] [PDF]

				R. Musolino, P. La Spina, S. Serra, P. Postorino, S. Calabro, R. Savica, G. Salemi, and G. Gallitto First-Ever Stroke Incidence and 30-Day Case Fatality in the Sicilian Aeolian Archipelago, Italy Stroke, December 1, 2005; 36(12): 2738 - 2741. [Abstract] [Full Text] [PDF]

				C. Sudlow Survival after stroke in south London BMJ, August 20, 2005; 331(7514): 414 - 415. [Full Text] [PDF]

				J. F. Fairhead, Z. Mehta, and P. M. Rothwell Population-based study of delays in carotid imaging and surgery and the risk of recurrent stroke Neurology, August 9, 2005; 65(3): 371 - 375. [Abstract] [Full Text] [PDF]

				P. Harrison, H. Segal, K. Blasbery, C. Furtado, L. Silver, and P. M. Rothwell Screening for Aspirin Responsiveness After Transient Ischemic Attack and Stroke: Comparison of 2 Point-of-Care Platelet Function Tests With Optical Aggregometry Stroke, May 1, 2005; 36(5): 1001 - 1005. [Abstract] [Full Text] [PDF]

				V. L. Feigin and K. Carter Editorial Comment--Stroke Incidence Studies One Step Closer to the Elusive Gold Standard? Stroke, September 1, 2004; 35(9): 2045 - 2047. [Full Text] [PDF]

				Neurology,  0, -1; -1: MASTER.