Thyroid status, disability and cognitive function, and survival in old age

JAMA. 2004 Dec 1;292(21):2591-9. doi: 10.1001/jama.292.21.2591.

Abstract

Context: Despite the equivocal outcomes of randomized controlled trials, general clinical opinion favors screening and treatment of elderly individuals with subclinical thyroid disorders.

Objectives: To determine whether subclinical thyroid dysfunction should be treated in old age and the long-term impact of thyroid dysfunction on performance and survival in old age.

Design, setting, and participants: A prospective, observational, population-based follow-up study within the Leiden 85-Plus Study of 87% of a 2-year birth cohort (1912-1914) in the municipality of Leiden, the Netherlands. A total of 599 participants were followed up from age 85 years through age 89 years (mean [SD] follow-up, 3.7 [1.4] years).

Main outcome measures: Complete thyroid status at baseline; disability in daily life, depressive symptoms, cognitive function, and mortality from age 85 years through 89 years.

Results: Plasma levels of thyrotropin and free thyroxine were not associated with disability in daily life, depressive symptoms, and cognitive impairment at baseline or during follow-up. Increasing levels of thyrotropin were associated with a lower mortality rate that remained after adjustments were made for baseline disability and health status. The hazard ratio (HR) for mortality per SD increase of 2.71 mIU/L of thyrotropin was 0.77 (95% confidence interval [CI], 0.63-0.94; P = .009). The HR for mortality per SD increase of 0.21 ng/dL (2.67 pmol/L) of free thyroxine increased 1.16-fold (95% CI, 1.04-1.30; P = .009).

Conclusions: In the general population of the oldest old, elderly individuals with abnormally high levels of thyrotropin do not experience adverse effects and may have a prolonged life span. However, evidence for not treating elderly individuals can only come from a well-designed, randomized placebo-controlled clinical trial.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Activities of Daily Living*
  • Aged
  • Aged, 80 and over
  • Cognition Disorders / physiopathology*
  • Depression / physiopathology
  • Disabled Persons
  • Female
  • Humans
  • Hypothyroidism / epidemiology
  • Hypothyroidism / physiopathology
  • Hypothyroidism / prevention & control
  • Male
  • Mortality*
  • Proportional Hazards Models
  • Prospective Studies
  • Survival Analysis
  • Thyroid Diseases / diagnosis
  • Thyroid Diseases / physiopathology*
  • Thyrotropin / blood
  • Thyroxine / blood
  • Triiodothyronine / blood

Substances

  • Triiodothyronine
  • Thyrotropin
  • Thyroxine