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Free Thyroxine Index and risk of stroke: Results from the National Health And Nutrition Examination Survey follow-up study

Adnan I. Qureshi, M. Fareed K. Suri, Abu Nasar, Jawad F. Kirmani, Afshin A. Divani, Wayne H. Giles

Med Sci Monit 2006; 12(12): CR501-506

ID: 469535

Published: 2006-12-01


Background: The long-term risks of stroke associated with hypothyroidism and hyperthyroidism is unknown. We evaluated the long-term risk of stroke with hypothyroidism and hyperthyroidism compared with euthyroid status.
Material/Methods: We used the 20-year follow-up data for adults aged 25 to 74 years who participated in the First National Health and Nutrition Examination Survey Follow-up Study. Hypothyroidism or hyperthyroidism
was diagnosed by free thyroxine index measurements at baseline evaluation and incident events were determined from hospital records and death certifi cates during follow-up. Relative risk (RR) of stroke, ischemic stroke, and intracerebral hemorrhage for each category of thyroid function were determined by Cox proportional hazards analysis after adjustment for potential confounding variables.
Results: A total of 5,269 participants (mean age 48±14 years; 2,379 men) were evaluated. Hypothyroidism and hyperthyroidism were diagnosed in 493 (9.4%) and 34 (0.7%) participants, respectively. After adjustment for covariates, a signifi cantly higher RR for all strokes and for ischemic stroke was observed in participants with hypothyroidism (RR 1.6; 95% confi dence interval (CI), 1.0–2.6 and RR 1.6, 95% CI, 1.0–2.7, respectively). Hyperthyroidism was not associated with an increased risk for
stroke.
Conclusions: An increased risk for stroke (particularly ischemic stroke) was observed in patients with hypothyroidism.

Keywords: Data Collection, Thyroxine - blood, Stroke - etiology, Risk Factors, Proportional Hazards Models, Middle Aged, Male, Hypothyroidism - complications, Hyperthyroidism - complications, Humans, Follow-Up Studies, Female, Adult, Aged, United States - epidemiology



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