Background and objective: Age seems to modify the relationship between hypothyroidism and cardiovascular disease (CVD). Although hypothyroidism in very elderly subjects has been associated with longevity, subclinical hypothyroidism in people ≤ 65 years seems to be related with an increased cardiovascular risk (CVR). The aim of this study was to determine the explanatory power of plasmatic TSH (pTSH) for the CVD, in different strata determined by age (≤ 55, 56-74, ≥ 75 years), sex and CVR factors.
Patients and methods: Six hundred and sixty-four men and women were differentiated into 18 strata and their explanatory models were developed using the multiple linear regression analysis. The dependent variable is the abdominal aortic calcification (AAC) according to the AAC-24 scale. The independent variables are: pTSH, age, smoking, BMI, SBP, DBP, fasting glucose, total cholesterol, HDL-cholesterol, LDL-cholesterol and C-reactive protein.
Results: Age is the main explanatory factor of AAC. The highest explanatory value of the β-standardized coefficient of the pTSH is observed in males ≤ 55 years (β=0.235, P=.043) and in females ≥ 75 years (β=0.405, P=.042). With increasing age, the prediction power improves in women and decreases in men. In men ≥ 75 years there is a negative correlation between pTSH and AAC (rho-Spearman=-0.213, P=.049).
Conclusions: A positive association is observed between pTSH and CVD in males ≤ 55 years and in women ≥ 75 years. The combination of multiple regression and the stratified analysis shows the complex influence of age in the relation between both variables.
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