Ischemic Stroke and Impact of Thyroid Profile at Presentation: A Systematic Review and Meta-analysis of Observational Studies

Abstract

Stroke is the fifth leading cause of mortality in the United States and a leading cause of disability. A complex relationship between thyroid hormone levels and severity of, and outcome after, stroke has been described. Our objective is to identify the association between baseline thyroid function profile and outcome after acute ischemic stroke. Studies looking at the association between thyroid function and functional stroke outcomes were identified from available electronic databases from inception to December 16, 2016. Study-specific risk ratios were extracted and combined with a random effects model meta-analysis. In the analysis of 12 studies with 5218 patients, we found that subclinical hypothyroidism was associated with better modified Rankin scale scores at 1 and 3 months (odds ratio [OR] 2.58, 95% confidence interval [CI] 1.13-5.91, P = .03 and OR 2.28, 95% CI 1.13-3.91, P = .003, respectively) compared with the euthyroid cases. Likewise, patients with higher initial thyrotropin-releasing hormone (TSH) and fT3 or T3 levels had favorable outcomes at discharge (mean differences of TSH .12 [95% CI .03-.22, P = .009] and of fT3 .36 (CI .20-.53, P < .0001]) and at 3 months (mean differences of TSH .25 [95% CI .03-.47, P = .03] and of T3 8.60 [CI 4.58-12.61, P < .0001]). Elevated initial TSH (clinical or subclinical hypothyroidism) may correspond to better functional outcomes, whereas low initial T3/fT3 might correlate with worse outcomes in acute ischemic stroke among clinically euthyroid patients. This complex relation merits further well-designed investigations. Whether correcting thyroid profile with hormone supplementation or antagonism may lead to improved outcomes will require large, prospective, interventional studies.