Table 2 Results of meta-analysis of all studies, silicotic studies and non-silicotic studies and subgroup analyses

Cohort studies (SMR)

63

1.55 (1.38–1.75)

5.68E-13

<0.0001

96.18

0.02

Cohort studies (SIR)

19

1.68 (1.45–1.96)

1.36E-11

4.59E-08

74.51

0.24

Cohort studies (RR)

1

1.65 (1.13–2.40)

0.01

1

0.72

Case-control mortality studies (OR)

5

1.82 (1.25–2.66)

0.0017

0.1070

51.17

0.51

Case-control incidence studies (OR)

9

1.34 (1.24–1.46)

<0.0001

0.2075

0

0.46

Case-control studies (MOR)

3

1.69 (1.26–2.26)

<0.0001

<0.0001

86.70

1.00

Proportional mortality studies (PMR)

2

1.10 (0.89–1.36)

0.38

0.10

62.02

1.00

Silicotic studies (SMR)

24

2.32 (1.91–2.81)

<0.0001

<0.0001

94.34

-

Silicotic studies (SIR)

4

2.49 (1.87–3.33)

<0.0001

0.377

25.04

-

Silicotic studies (OR)

3

2.56 (1.84–3.57)

<0.0001

0.345

2.65

-

Silicotic studies (MOR)

3

1.88 (1.31–2.71)

0.0006

<0.0001

86.98

-

Non-silicotic studies (SMR)

4

1.78 (1.07–2.96)

0.027

0.013

74.37

-

Non-silicotic studies (SIR)

2

1.18 (0.86–1.62)

0.292

0.192

41.21

-

  ≤ 1990

16

2.37 (1.76–3.19)

1.24E-08

2.92E-94

95.58

0.35

 1991–2000

21

1.44 (1.21–1.71)

2.97E-05

1.25E-30

89.89

0.16

  > 2000

26

1.30 (1.16–1.46)

1.05E-05

9.98E-49

93.50

0.60

 Mine

18

1.48 (1.18–1.86)

0.00

4.73E-59

97.17

0.18

 Foundry

4

1.51 (0.99–2.29)

0.05

0.02

86.53

0.75

 Pottery

7

1.14 (1.05–1.23)

0.00

0.27

0.02

1.00

 Cement

4

0.87 (0.42–1.82)

0.71

<0.0001

84.87

0.75

 Construction

2

1.55 (1.31–1.82)

1.94E-07

0.66

0.00

1.00

 Stone & granite

8

1.32 (1.15–1.50)

6.24E-05

0.01

65.17

0.72

 Mixed

19

2.03 (1.61–2.56)

1.68E-09

96.95

0.73

 Europe

26

1.54 (1.25–1.89)

4.95E-05

4.09E-33

95.70

0.13

 USA

15

1.24 (1.12–1.38)

6.24E-05

5.32E-07

79.80

0.06

 Canada

5

2.14 (1.46–3.13)

9.27E-05

2.34E-32

95.70

0.82

 Australia

2

1.73 (1.51–1.98)

7.65E-15

0.26

19.61

1.00

 Asia

14

1.74 (1.27–2.39)

<0.0001

97.56

0.75

 Absent

13

1.32 (1.14–1.54)

<0.0001

1.79E-13

87.15

0.06

 Present

30

1.35 (1.17–1.57)

7.28E-05

7.37E-55

94.47

0.55

 Not adjusted

61

1.55 (1.37–1.75)

4.16E-12

96.37

0.02

 Adjusted

2

1.83 (1.51–2.22)

7.23E-10

0.43

0.00

1.00

 1–3

6

2.56 (1.57–4.19)

0.00

2.35E-65

96.18

1.00

 4–6

35

1.57 (1.36–1.82)

9.02E-10

1.68E-80

93.07

0.45

 7–9

15

1.24 (1.01–1.52)

0.042025

1.56E-44

97.23

0.17

 0 < CSDE ≤ 0.83

5

1.19 (1.02–1.39)

0.02

0.02

68.92

0.23

 0.83 < CSDE ≤ 3.9

5

1.27 (0.89–1.82)

0.19

1.04E-24

97.57

0.48

 3.9 < CSDE ≤ 8.35

4

1.33 (0.94–1.87)

0.10

2.97E-10

91.94

0.75

 CSDE > 8.35

5

1.36 (0.87–2.13)

0.18

1.15E-21

96.33

0.82

 ≤ 1990

4

2.32 (1.50–3.58)

<0.0001

0.07

64.63

0.75

 1991–2000

6

1.77 (1.17–2.69)

0.01

5.07E-09

85.81

0.47

  > 2000

9

1.54 (1.40–1.70)

8.29E-18

0.41

17.30

1.00

 Mine

2

1.67 (1.32–2.13)

2.55E-05

0.07

69.32

1.00

 Foundry

4

1.40 (1.23–1.58)

2.67E-07

0.52

7.15

0.33

 Pottery

1

2.34 (0.62–8.84)

0.21

1

0.33

 Cement

3

1.34 (1.01–1.76)

0.04

0.43

12.61

1.00

 Construction

1

1.50 (1.26–1.79)

5.04E-06

1

1.00

 Granite

3

1.94 (1.55–2.44)

1.33E-08

0.93

0.00

1.00

 Mixed

5

2.13 (1.18–3.87)

0.01

4.08E-05

85.96

0.82

 Europe

13

1.78 (1.48–2.14)

1.16E-09

9.18E-08

77.40

0.13

 Canada

2

1.42 (0.52–3.93)

0.49

0.05

74.77

1.00

 Australia

1

1.89 (1.57–2.28)

2.26E-11

1

1.00

 Asia

3

1.38 (1.10–1.73)

<0.0001

0.28

6.72

1.00

 Absent

3

1.94 (1.55–2.44)

1.33E-08

0.93

0.00

1.00

 Present

12

1.57 (1.32–1.87)

4.14E-07

4.45E-08

80.28

0.64

 1–3

3

1.99 (1.19–3.30)

0.01

0.95

0.00

1.00

 4–6

11

1.55 (1.28–1.87)

5.74E-06

2.36E-08

82.02

0.76

 7–9

1

1.61 (1.21–2.14)

<0.001

1

0.76