ABC | Volume 112, Nº6, June 2019

761 Original Article Rajão et al Subclinical thyroid dysfunction and arrhythmias Arq Bras Cardiol. 2019; 112(6):758-766 Figure 1 – Inclusion of participants from the ELSA-Brasil study baseline, 2008-2010. TSH: thyroid-stimulating hormone; FT4: free thyroxine; ECG: electrocardiogram. –47 participants (discrepant TSH (40) or FT4 (7) test results) –111 participants (serum TSH and FT4 levels suggesting non- thyroid dysfunctions) –06 participants (serum TSH concentrations > 20 μU/mL with normal FT4 levels) –448 participants (use of medications that could interfere with TSH and/or FT4 assays) –79 participants (43 clinical hypothyroidism; 36 clinical hyperthyroidism) –1073 participants (use of levothyroxine (994) or antithyroid agents (79)) 15,105 14,657 14,610 14,531 14,420 13,347 13,341 13,341 (analysis of HR 11,795 ECGs) 698 Subclinical hypothyroidism (615 ECGs) 12,450 Euthyroidism (11.003 ECGs) 193 Subclinical hyperthyroidism (177 ECGs) Table 1 – Characteristics of participants categorized by thyroid function group, Longitudinal Study of Adult Health, ELSA–Brasil, 2008-2010 Subclinical hypothyroidism Euthyroidism Subclinical hyperthyroidism Total N (%) 698 (5.23%) 12,450 (93.32%) 193 (1.45%) 13,341 (100%) Age, y * 54 (47-61) † 51 (45-58) 53 (46-59) † 51 (45-58) Female sex (%) 381 (54.58%)‡ 6,433 (51.67%) 123 (63.73%)‡ 6,937 (52.00%) BMI (kg/m 2 ) * 26.80 (24.03-29.96) § 26.27 (23.63-29.48) 26.16 (23.55-29.39) † 26.30 (23.65-29.52) Education ≥ completed secondary education (%) 589 (84.38%) 10,887 (87.45%) 163 (84.46%) 11,639 (87.24%) Skin color (%) white 426 (61.03%)§ 6,283 (50.47%) 72 (37.30%)§ 6,781 (50.82%) brown 177 (25.36%) 3,547 (28.49%) 54 (27.98%) 3,778 (28.32%) black 60 (8.60%)§ 2,032 (16.32%) 54 (27.98%)§ 2,146 (16.09%) others 35 (5.01%) 588 (4.72%) 13 (6.74%) 636 (4.77%) Hypertension (%) 243 (34.81%) 4,258 (34.20%) 87 (45.08%)§ 4,588 (34.39%) Diabetes mellitus (%) 145 (20.77%) 2,493 (20.02%) 46 (23.83%) 2,684 (20.12%) Dyslipidemia (%) 547 (78.37%)† 9,338 (75.00%) 138 (71.50%) 10,023 (75.13%) LDL > 130 395 (56.59%) 7,059 (56.70%) 112 (58.03%) 7,566 (56.71%) TGC > 150 254 (36.39%)§ 3,850 (30.92%) 58 (30.05%) 4,162 (31.20%) Coronary artery disease (%) 44 (6.30%)† 531 (4.27%) 10 (5.18%) 585 (4.39%) CHF (%) 14 (2.01%) 170 (1.37%) 4 (2.07%) 188 (1.41%) COPD (%) 17 (2.44%)† 241 (1.94%) 6 (3.11%) 264 (1.98%) Chagas’ disease (%) 9 (1.29%) 112 (0.90%) 0 (0.00%) 121 (0.91%) Excessive alcohol (%) 43 (6.16%) 992 (7.97%) 10 (5.18%) 1,045 (7.83%) Smoking status Current smoker 66 (9.46%)§ 1,689 (13.56%) 38 (19.69%)§ 1,793 (13.43%) Former smoker 247 (35.39%)§ 3,639 (29.23%) 64 (33.16%) 3,950 (29.61%) No smoking 385 (55.16%) 7,122 (57.21%) 91 (47.15%)§ 7,598 (56.96%) TSH (μU/mL) * 5.065 (4.43-6.26) § 1.48 (1.04-2.18) 0.28 (0.17-0.34) § 1.53 (1.04-2.32) FT4 (ng/dl) * 1.10 (1.0-1.2) 1.145 (1.05-1.235) 1.20 (1.10-1.40) § 1.10 (1.00-1.24) BMI: body mass index; LDL: lipoprotein low density; TGC: triglycerides; CHF: congestive heart failure; COPD: chronic obstructive pulmonary disease; Chagas disease: positive serology in the Chagatest – ELISA assay; TSH: thyroid-stimulating hormone; FT4: free thyroxine; * Median (Interquartile range); † Statistically significant difference (p < 0.05) without adjustment, compared to the euthyroidism; ‡p < 0.05 after adjustment by age; § p < 0.05 after adjustment by age and sex.