Abstract
Objective: To investigate the effect of autoimmune thyroiditis (AIT) on risk of stroke and to assess whether any increased risk (1) varied by AIT duration, and (2) was independent of classic cardiovascular risk factors.
Methods: This was a large historical cohort study using data from The Health Improvement Network Database. Rates of first stroke during follow-up in thyroxine-treated patients with AIT (n = 34,907) were compared with those in matched individuals without AIT (n = 149,632) using random-effects Poisson regression models.
Results: There was strong evidence for a slightly increased risk of stroke in patients with AIT (adjusted rate ratio = 1.10, 95% confidence interval: 1.01–1.20). The observed increase was partly independent of cardiovascular risk factors. Higher effect sizes were identified in the first year after AIT diagnosis (rate ratio = 1.33, 95% confidence interval: 1.14–1.56) but not in the long-term, consistent with a residual effect of hypothyroidism.
Conclusion: Our results support the hypothesis of a slightly increased risk of stroke in patients with AIT. The higher effect size found soon after AIT diagnosis suggests an increased cardiovascular risk due to thyroid-hormone deficiency rather than a cumulative effect of autoimmune pathology. Better screening and early treatment of patients with asymptomatic hypothyroid AIT could help reduce excess risk of stroke in the first year after diagnosis.
GLOSSARY
- AF=
- atrial fibrillation;
- AIT=
- autoimmune thyroiditis;
- BMI=
- body mass index;
- CHD=
- coronary heart disease;
- CHF=
- congestive heart failure;
- CI=
- confidence interval;
- RR=
- rate ratio;
- THIN=
- The Health Improvement Network
Footnotes
Go to Neurology.org for full disclosures. Funding information and disclosures deemed relevant by the authors, if any, are provided at the end of the article. The Article Processing Charge was paid by the Wellcome Trust.
Supplemental data at Neurology.org
- Received June 25, 2013.
- Accepted in final form January 16, 2014.
- © 2014 American Academy of Neurology
This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
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