Levothyroxine may lower dementia risk in hypothyroid women with AF

  • Wändell P & al.
  • Clin Drug Investig
  • 14 Dec 2018

  • curated by Susan London
  • Clinical Essentials
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Takeaway

  • Women with atrial fibrillation (AF) who are hypothyroid have lower dementia risk when prescribed levothyroxine (Synthroid, others).
  • Levothyroxine did not have benefit in nonhypothyroid women or in men, whether hypothyroid or not.

Why this matters

  • Imperative to address preventable causes of dementia.

Key results

  • During mean 5.7-year follow-up, 6.2% of patients received dementia diagnosis.
  • For women, dementia risk (peers without hypothyroidism diagnosis, without levothyroxine prescription as comparator):
    • With hypothyroidism diagnosis, with levothyroxine prescription, aOR: 0.67 (P<.05>
    • Without hypothyroidism diagnosis, with levothyroxine prescription, aOR: 0.91 (P=NS).
  • Benefit among hypothyroid women was greater in analyses restricted to those aged 77-85 years (aHR, 0.41; P<.05>
  • For men, dementia risk (peers without hypothyroidism diagnosis, without levothyroxine prescription as comparator):
    • With hypothyroidism diagnosis, with levothyroxine prescription, aOR: 1.72 (P=NS).
    • Without hypothyroidism diagnosis, with levothyroxine prescription, aOR: 0.41 (P=NS).

Study design

  • Swedish population-based cohort study of 12,057 dementia-free patients aged ≥45 years with AF diagnosis, seen in primary care centers.
  • Main outcome: all-cause dementia.
  • Funding: Agreement on Medical Education and Research; others.

Limitations

  • Patients not registered in primary care excluded.
  • Reliance on diagnosis codes, prescriptions.
  • Limited power among men.
  • Treatment and survival biases.