Thyroid Dysfunction States and Incident Cardiovascular Events: The Tehran Thyroid Study.

Area of Science:

• Endocrinology
• Cardiology
• Epidemiology

Background:

• Thyroid dysfunction is common and may influence cardiovascular health.
• Middle-Eastern populations exhibit a high incidence of cardiovascular disease (CVD)/coronary heart disease (CHD).
• Understanding the relationship between thyroid status and CVD/CHD is crucial for public health.

Purpose of the Study:

• To investigate the association between various thyroid function states and the incidence of CVD/CHD.
• To examine this relationship in a Middle-Eastern cohort known for high CVD/CHD rates.

Main Methods:

• A cohort of 3975 participants was categorized into five thyroid function groups: euthyroid, subclinical hypothyroidism, overt hypothyroidism, subclinical hyperthyroidism, and overt hyperthyroidism, based on TSH and FT4 levels.
• Multivariable Cox proportional hazard models were employed to analyze the association between thyroid function states and incident CVD/CHD over a median follow-up of 11.2 years.
• The analysis accounted for age and sex, with the euthyroid state serving as the reference group.

Main Results:

• No significant difference in prevalent CVD cases at baseline was observed across thyroid function groups.
• During follow-up, no statistically significant association was found between any thyroid dysfunction state and the incidence of CVD/CHD, even after adjusting for age and sex.
• Hazard ratios for CVD events in subclinical hypothyroidism, overt hypothyroidism, subclinical hyperthyroidism, and overt hyperthyroidism were 1.21, 0.76, 0.81, and 1.48, respectively, with wide confidence intervals indicating no significant risk.

Conclusions:

• Thyroid function status, encompassing hypothyroidism and hyperthyroidism, does not appear to be a significant predictor of cardiovascular disease or coronary heart disease incidence in this Middle-Eastern population.
• The findings suggest that thyroid dysfunction may not play a direct role in the development of CVD/CHD in this specific demographic, warranting further investigation in diverse populations.