Subclinical thyroid dysfunctions are independent risk factors for mortality in a 7.5-year follow-up: the Japanese–Brazilian thyroid study

• Published in: European journal of endocrinology Vol. 162; no. 3; pp. 569 - 577
• Main Authors: Sgarbi, José A, Matsumura, Luiza K, Kasamatsu, Teresa S, Ferreira, Sandra R, Maciel, Rui M B
• Format: Journal Article
• Language: English
• Published: Bristol BioScientifica 01.03.2010; European Society of Endocrinology
• Subjects: Adult; Aged; Aged, 80 and over; Analysis of Variance; Asian Continental Ancestry Group; Biological and medical sciences; Brazil - ethnology; Cardiovascular Diseases - ethnology; Cardiovascular Diseases - mortality; Chi-Square Distribution; Clinical Study; Cross-Sectional Studies; Endocrinopathies; Epidemiology; Female; Follow-Up Studies; Fundamental and applied biological sciences. Psychology; General aspects; Humans; Kaplan-Meier Estimate; Male; Medical sciences; Middle Aged; Non tumoral diseases. Target tissue resistance. Benign neoplasms; Proportional Hazards Models; Prospective Studies; Public health. Hygiene; Public health. Hygiene-occupational medicine; Risk Factors; Severity of Illness Index; Statistics, Nonparametric; Thyroid Diseases - ethnology; Thyroid Diseases - mortality; Thyroid. Thyroid axis (diseases); Vertebrates: endocrinology; South America; Brazil; Asia; Japan; America; Endocrinopathy; Endocrine gland; Mortality; Independence; Thyroid diseases; Thyroid gland; Epidemiology; Japanese; Surveillance; Follow up study; Thyroid function; Statistical model; Risk factor; Endocrinology
• ISSN: 0804-4643; 1479-683X; 1479-683X
• DOI: 10.1530/EJE-09-0845

ObjectiveThe currently available data concerning the influence of subclinical thyroid disease (STD) on morbidity and mortality are conflicting. Our objective was to investigate the relationships between STD and cardiometabolic profile and cardiovascular disease at baseline, as well as with all-cause and cardiovascular mortality in a 7.5-year follow-up.DesignProspective, observational study.MethodsAn overall of 1110 Japanese–Brazilians aged above 30 years, free of thyroid disease, and not taking thyroid medication at baseline were studied. In a cross-sectional analysis, we investigated the prevalence of STD and its relationship with cardiometabolic profile and cardiovascular disease. All-cause and cardiovascular mortality rates were assessed for participants followed for up to 7.5 years. Association between STD and mortality was drawn using multivariate analysis, adjusting for potential confounders.ResultsA total of 913 (82.3%) participants had euthyroidism, 99 (8.7%) had subclinical hypothyroidism, and 69 (6.2%) had subclinical hyperthyroidism. At baseline, no association was found between STD and cardiometabolic profile or cardiovascular disease. Multivariate-adjusted hazard ratios (HRs (95% confidence interval)) for all-cause mortality were significantly higher for individuals with both subclinical hyperthyroidism (HR, 3.0 (1.5–5.9); n=14) and subclinical hypothyroidism (HR, 2.3 (1.2–4.4); n=13) than for euthyroid subjects. Cardiovascular mortality was significantly associated with subclinical hyperthyroidism (HR, 3.3 (1.4–7.5); n=8), but not with subclinical hypothyroidism (HR, 1.6 (0.6–4.2); n=5).ConclusionIn the Japanese–Brazilian population, subclinical hyperthyroidism is an independent risk factor for all-cause and cardiovascular mortality, while subclinical hypothyroidism is associated with all-cause mortality.