Table 2 Subgroup and heterogeneity analyses of pooled RRs of primary outcomes

Factors

 All hypothyroidism

4

13,444/593,499

1.13 (1.04–1.23)

0.0%

Reference

2

282/2836

1.83 (0.72–4.62)

90.0%

0.75

 SCH

8

3400/21,623

1.12 (0.89–1.42)

55.8%

0.74

5

819/32,086

2.00 (1.34–2.97)

47.8%

Reference

 OHypo

1

18/474

2.54 (0.87–7.41)

-

0.30

-

-

-

-

-

 Convenience sample

4

1406/8946

1.08 (0.66–1.79)

58.2%

0.73

5

398/6595

2.33 (1.39–3.91)

70.7%

Reference

  Cardiac patients^b

3

1277/8149

1.15 (0.68–1.94)

67.7%

-

4

393/5596

2.22 (1.28–3.83)

76.5%

-

 Population-based

9

15,456/606,650

1.12 (1.00–1.25)

36.8%

Reference

2

703/28,327

1.43 (1.10–1.86)

0.0%

0.33

 ≥80 years

-

-

-

-

-

-

-

-

-

 65–79 years

8

3417/20,298

1.06 (0.89–1.27)

37.4%

0.45

2

236/3077

1.91 (0.61–5.93)

82.3%

0.68

 <65 years

5

13,445/595,298

1.19 (1.02–1.39)

51.0%

Reference

5

865/31,845

2.07 (1.39–3.07)

61.8%

Reference

 Europe

7

13,907/600,542

1.10 (0.95–1.26)

31.7%

0.23

4

814/31,087

1.91 (1.28–2.86)

52.8%

0.26

 North America

4

2675/12,727

1.08 (0.95–1.24)

15.2%

0.22

1

205/2430

1.14 (0.76–1.71)

-

Reference

 Asia

1

18/474

2.54 (0.87–7.41)

-

Reference

2

82/1405

3.02 (2.00–4.56)

0.0%

0.10

 Oceania

1

262/1853

1.80 (1.20–2.70)

-

0.63

-

-

-

-

-

 ≥50%

9

15,773/610,042

1.07 (0.98–1.18)

19.9%

0.08

3

708/29,326

1.47 (1.12–1.94)

2.3%

Reference

 <50%

4

1089/5554

1.47 (1.04–2.07)

40.9%

Reference

4

393/5596

2.22 (1.28–3.83)

76.5%

0.52

 ≥10 years

5

3615/45,383

1.18 (0.98–1.42)

55.4%

Reference

3

708/29,326

1.47 (1.12–1.94)

2.3%

Reference

 5–10 years

2

11,491/557,482

1.13 (1.02–1.25)

0.0%

0.73

-

-

-

-

-

 <5 years

6

1756/12731

1.07 (0.75–1.53)

53.9%

0.59

4

393/5596

2.22 (1.28–3.83)

76.5%

0.52

Factors

 All hypothyroidism

5

2724/20,707

0.99 (0.70–1.39)

42.0%

0.35

21

98,621^c/876,811

1.21 (1.07–1.37)

87.6%

0.51

 SCH

12

2549/137,310

1.15 (1.00–1.32)

0.0%

Reference

18

13,529/159,104

1.32 (1.13–1.54)

65.9%

Reference

 OHypo

-

-

-

-

-

1

6/474

1.78 (0.21–14.98)

-

0.80

 Convenience sample

5

1454/12,229

1.15 (0.95–1.39)

0.0%

0.70

20

9004^c/54,577

1.45 (1.27–1.66)

63.4%

0.009

  Cardiac patients^b

2

1333/9820

1.10 (0.83–1.45)

0.0%

-

13

4643^c/38,219

1.51 (1.26–1.81)

65.7%

-

 Population-based

12

3819/145,788

1.08 (0.86–1.36)

33.3%

Reference

20

103,152/981,812

1.10 (0.95–1.28)

91.7%

Reference

 ≥80 years

1

87/539

0.55 (0.33–0.93)

-

0.004

3

6216/18,267

1.05 (0.55–1.98)

95.2%

Reference

 65–79 years

11

2799/22,989

1.08 (0.94–1.23)

0.0%

0.04

20

9706/49,057

1.15 (1.03–1.29)

34.7%

0.73

 <65 years

5

2387/134,489

1.53 (1.16–2.01)

0.0%

Reference

17

96,234^c/969,065

1.38 (1.19–1.60)

89.3%

0.22

 Europe

7

1807/13,446

0.96 (0.74–1.23)

33.4%

0.045

19

92,477/847,659

1.09 (0.95–1.26)

83.2%

0.92

 North America

5

2544/24,417

1.08 (0.90–1.29)

0.0%

0.097

10

8176^c/40,891

1.26 (1.12–1.41)

54.5%

0.50

 Asia

4

731/118,301

1.72 (1.13–2.62)

0.0%

Reference

10

10,671/143,981

1.75 (1.42–2.15)

60.1%

0.07

 Oceania

1

191/1853

1.50 (0.90–2.50)

-

0.70

1

832/3858

1.06 (0.86–1.31)

-

Reference

 ≥50%

12

3814/149,254

1.06 (0.87–1.29)

29.5%

Reference

22

103,550/990,510

1.13 (0.97–1.31)

91.1%

Reference

 <50%

5

1459/8763

1.23 (0.96–1.58)

0.0%

0.35

18

8606^c/45,879

1.42 (1.25–1.63)

65.8%

0.03

 ≥10 years

7

3338/139,867

1.21 (0.98–1.50)

16.2%

0.12

9

14,896/165,332

1.25 (0.98–1.59)

89.7%

0.44

 5–10 years

5

399/4517

1.19 (0.94–1.52)

0.0%

0.20

13

88,149^c/822,913

1.10 (0.92–1.32)

85.8%

Reference

 <5 years

5

1536/13,633

0.88 (0.63–1.23)

34.0%

Reference

18

9111^c/48,144

1.37 (1.19–1.58)

72.7%

0.09