Long-Term Outcomes of Ischemic Stroke of Undetermined Mechanism: A Population-Based Prospective Cohort

Negar Morovatdar; Amanda G Thrift; Moira K Kapral; Réza Behrouz; Hamidreza Saber; Amin Amiri; Mohammad Taghi Farzadfard; Naghmeh Mokhber; Saverio Stranges; Mahmoud Reza Azarpazhooh

doi:10.1159/000482019

Long-Term Outcomes of Ischemic Stroke of Undetermined Mechanism: A Population-Based Prospective Cohort

Neuroepidemiology. 2017;49(3-4):160-164. doi: 10.1159/000482019. Epub 2017 Nov 21.

Authors

Negar Morovatdar¹, Amanda G Thrift², Moira K Kapral^{3

4}, Réza Behrouz⁵, Hamidreza Saber⁶, Amin Amiri⁷, Mohammad Taghi Farzadfard⁷, Naghmeh Mokhber^{8

9}, Saverio Stranges^{10

11}, Mahmoud Reza Azarpazhooh^{7

10

12}

Affiliations

¹ Clinical Research Unit, Mashhad University of Medical Sciences, Mashhad, Iran.
² Stroke and Ageing Research, Department of Medicine, School of Clinical Sciences at Monash Health, Monash University, Clayton, Victoria, Australia.
³ Department of Medicine and Institute of Health Policy, Management and Evaluation, University of Toronto, Toronto, Ontario, Canada.
⁴ Institute for Clinical Evaluative Sciences, Toronto, Ontario, Canada.
⁵ Department of Neurology, Lozano-Long School of Medicine, University of Texas Health, San Antonio, Texas, USA.
⁶ Department of Neurology, Wayne State University School of Medicine, Detroit, Michigan, USA.
⁷ Department of Neurology, Mashhad University of Medical Sciences, Mashhad, Iran.
⁸ Department of Psychiatry and Behavioral Neurosciences, Western University, London, Ontario, Canada.
⁹ Department of Psychiatry, Mashhad University of Medical Sciences, Mashhad, Iran.
¹⁰ Department of Epidemiology and Biostatistics, Western University, London, Ontario, Canada.
¹¹ Department of Population Health, Luxembourg Institute of Health, Strassen, Luxemburg.
¹² Department of Clinical Neurological Science, Western University, London, Ontario, Canada.

PMID: 29161693
DOI: 10.1159/000482019

Abstract

Background and purpose: Little is known about the short- and long-term outcomes of ischemic stroke of undetermined mechanism (ISUM).

Methods: Subjects were recruited from the Mashhad Stroke Incidence Study. Ischemic stroke (IS) was classified on the basis of the TOAST criteria. We further categorized patients with ISUM into ISUMneg (negative clinical/test results for large artery, small artery) and ISUMinc (incomplete investigations). Cox proportional hazard models and the competing-risk regression model were used to compare 1 and 5 years mortality (all-causes) and recurrent rate among IS subtypes.

Results: Overall, 1-year mortality was higher in those with ISUMinc than in ISUMneg (adjusted hazard ratio [aHR] 1.6, 95% CI 1.01-2.8; p = 0.04) and in other stroke subtypes. Cardioembolic stroke was associated with the greatest risk of stroke recurrence at one year (aHR 4.9, 95% CI 1.8-12.9; p = 0.001) and 5 years (HR 2.1, 95% CI 1.1-3.7; p = 0.01) as compared to ISUMneg.

Conclusions: The classification of ISUM as a single group may lead to over- or underestimation of mortality and recurrence in this major category of IS. A better definition of ISUM is necessary to predict death and recurrence accurately.

Keywords: Etiology; Prognosis and population-based studies; Stroke; Stroke of undetermined mechanism.

Publication types

Research Support, Non-U.S. Gov't

MeSH terms

Aged
Brain Ischemia / epidemiology*
Cohort Studies
Female
Humans
Iran / epidemiology
Male
Middle Aged
Patient Outcome Assessment*
Proportional Hazards Models
Prospective Studies
Recurrence
Risk Factors
Stroke / epidemiology*