Table 3 Univariate and multivariate analysis to assess potential exposure factors associated with incident hypothyroidism.

Age (years)

< 30

1

1

30–40

5.2

1.2–22.8

0.027

10.8

1.4–84.5

0.024

40–50

4.7

1.1–20.4

0.037

7.4

0.9–57.8

0.057

50–60

3.5

0.8–15.5

0.099

6.3

0.8–50.5

0.082

60–70

4.2

1.0–18.7.0.7

0.056

8.3

1.0–67.0

0.047

≥ 70

5.1

1.1–24.2

0.039

10.3

1.2–88.4

0.034

Sex

Men

1

1

Women

2.9

1.7–5.0.7.0

< 0.001

2.7

1.5–5.5

0.004

Smoking

Non-smokers

1

1

Former smokers

0.5

0.3–0.9

0.025

0.8

0.4–1.5

0.486

Active smokers

0.8

0.5–1.4

0.828

1.4

0.7–2.6

0.350

BMI (kg/m2)

< 25

1

-

-

-

25–30

0.9

0.4–1.6

0.758

-

-

-

≥ 30

1.0

0.5–1.7

0.949

-

-

-

Diabetes mellitus

No

1

-

-

-

Yes

0.5

0.2–1.2

0.101

-

-

-

Glucose metabolism abnormalities

No

1

-

-

-

Prediabetes

0.5

0.2–1.3

0.174

-

-

-

Diabetes

0.4

0.2–1.1

0.077

-

-

-

TPO antibodies (IU/L)

< 20

1

1

20–50

4.2

2.1–8.5

< 0.001

3.4

1.6–7.4

0.002

50–150

5.5

2.3–12.9

< 0.001

4.7

1.7–12.6

0.002

≥ 150

9.4

4.7–18.7

< 0.001

6.9

3.3–14.8

< 0.001

TSH (mIU/L)

0.20–1.50

1

1

1.50–2.80

1.5

0.7–3.1

0.303

1.5

0.7–3.4

0.316

2.80–5.80

5.4

2.7–10.8

< 0.001

4.6

2.2–10.0

< 0.001

Urinary iodine (µg/L)

< 50

1

-

-

-

50–100

1.0

0.4–2.5

0.992

-

-

-

100–200

1.5

0.6–3.6

0.383

-

-

-

200–300

1.6

0.6–4.3

0.400

-

-

-

≥ 300

1.2

0.3–5.2

0.762

-

-

-

Ferritin (µg/L)

> 100

1

1

100 − 30

1.2

0.7–2.1

0.531

0.8

0.4–1.6

0.544

30 − 15

1.1

0.5–2.3

0.806

0.8

0.3–2.0.3.0

0.601

≤ 15

2.0

1.1–3.9

0.029

1.1

0.5–2.6

0.770

Area of residence

Center

1

-

-

-

North

0.9

0.4–2.1

0.728

-

-

-

Northeast

0.9

0.4–2.1

0.738

-

-

-

East

1.7

0.8–3.3

0.137

-

-

-

South

1.2

0.7–2.2

0.462

-

-

-