Table 2 Characteristics of the cohort studies included in the Individual Participant Data meta-analysis and population-based register-linkage study according to preterm and term birth

From: ADHD symptoms and diagnosis in adult preterms: systematic review, IPD meta-analysis, and register-linkage study

Characteristics

Preterm (<37 + 0 wks + days)

Term-born controls (37 + 0–41 + 6 wks + days)

N or M

% or SD

N or M

% or SD

Participants, n

    

 All Cohorts

1385

45.9

1633

54.1

 AYLSa

171

19.0

727

81.0

 BLSb

234

51.5

220

48.5

 EPICurec

117

69.6

51

30.4

 ESTERd

372

54.1

315

45.9

 HeSVAe

111

53.4

97

46.6

 NTNUf

60

42.3

82

57.7

 NZVLBWg

230

76.9

69

23.1

 VICSh

90

55.6

72

44.4

 Population-based register-linkage studyi

37,538

5.2

691,616

95.9

Sex, female

    

 All Cohorts

721

52.1

891

55.3

 AYLS

85

49.7

397

54.6

 BLS

109

48.2

117

51.8

 EPICure

64

54.7

32

62.7

 ESTER

201

54.2

170

54.0

 HeSVA

62

55.9

55

56.7

 NTNU

28

46.7

48

58.5

 NZVLBW

126

54.8

36

52.2

 VICS

46

51.1

36

50.0

 Population-based register-linkage study

17,082

45.5

339,994

 

Gestational age, wk

    

 All Cohorts

30.9

3.9

39.6

1.3

 AYLS

33.9

2.6

39.4

1.3

 BLS

30.5

2.1

39.6

1.1

 EPICure

24.5

0.7

–

–

 ESTER

34.3

2.3

39.9

1.2

 HeSVA

29.3

2.4

40.0

1.1

 NTNU

29.1

2.7

39.6

1.0

 NZVLBW

29.2

2.5

–

–

 VICS

27.0

2.4

39.0

1.2

 Population-based register-linkage study

34.3

2.3

39.6

1.2

Birthweight z-score

    

 All Cohorts

−0.02

1.2

0.61

1.1

 AYLS

0.42

1.1

0.74

1.1

 BLS

−0.45

1.4

0.21

0.985

 EPICure

−0.55

0.736

–

–

 ESTER

0.19

1.1

0.57

1.0

 HeSVA

−0.44

1.2

0.63

1.1

 NTNU

0.06

1.1

0.97

0.9

 NZVLBW

−0.32

1.2

–

–

 VICS

0.07

1.2

0.37

0.9

 Population-based register-linkage study

0.17

1.1

0.68

1.0

Small-for-gestational age (<−2 SD), yes

    

 All Cohorts

55

4.0

*

*

 AYLS

*

*

13

1.8

 BLS

12

5.1

7

3.2

 EPICure

*

*

–

–

 ESTER

15

4.0

11

3.5

 HeSVA

8

7.2

3

3.1

 NTNU

*

*

0

0

 NZVLBW

13

5.7

–

–

 VICS

*

*

*

*

 Population-based register-linkage study

1227

3.3

4812

0.7

Age at follow-up, yearsj

    

 All Cohorts

23.6

2.5

24.6

2.1

 AYLS

25.5

0.6

25.5

0.6

 BLS

26.3

0.7

26.3

0.7

 EPICure

19.3

0.6

19.2

0.6

 ESTER

23.1

1.3

23.4

1.2

 HeSVA

24.6

2.1

24.6

2.2

 NTNU

26.4

0.6

26.5

0.5

 NZVLBW

23.4

0.5

23.7

0.6

 VICS

18.6

0.5

18.7

0.5

 Population-based register-linkage study

34.31

2.34

39.59

1.22

Highest parental education attainedk, lower secondary or less

  

 All Cohorts

198

14.3

145

8.9

 AYLS

16

9.5

75

10.4

 BLS

29

12.7

31

15.1

 EPICure

22

19.8

2

3.9

 ESTER

32

8.7

19

6.07

 HeSVA

11

10.1

6

6.2

 NTNU

8

11.9

4

4.6

 NZVLBW

65

29.0

–

–

 VICS

15

29.8

8

27.6

 Population-based register-linkage study

4776

12.7

69,768

10.1

Neurosensory impairment, any

    

 All Cohorts

121

8.7

27

1.7

 AYLS

16

13.2

26

3.6

 BLS

44

36.4

1

0.4

 EPICure

22

18.2

–

–

 ESTER

7

5.8

–

–

 HeSVA

5

4.1

–

–

 NTNU

6

5.0

–

–

 NZVLBW

21

17.4

–

–

 VICS

0

0

–

–

 Population-based register-linkage study

1774

4.7

8383

1.2

Preterm only characteristics

 

Bronchopulmonary dysplasia

    

 All Cohorts

323

38.6

–

–

 AYLS

*

*

–

–

 BLS

124

38.4

–

–

 EPICure

84

26.0

–

–

 ESTER

–

–

–

–

 HeSVA

25

7.7

–

–

 NTNU

13

4.0

–

–

 NZVLBW

48

14.9

–

–

 VICS

28

8.7

–

–

 Population-based register-linkage study

587

1.6

–

–

Intravehicular hemorrhage. Grades 1–4

    

 All Cohorts

246

25.7

–

–

 AYLS

7

2.8

–

–

 BLS

46

18.7

–

–

 EPICure

78

31.7

–

–

 ESTER

–

–

–

–

 HeSVA

14

5.7

–

–

 NTNU

6

2.4

–

–

 NZVLBW

62

25.2

–

–

 VICS

33

13.4

–

–

 Population-based register-linkage study

148

0.4

–

–

  1. *Cohort counts between 1 and 5, and where only one cohort has less than five the overall total of the cohorts are not presented to protect the privacy of the participants.
  2. – Data not available.
  3. aArvo Ylppö Longitudinal Study (Uusimaa, Finland, born 1985).
  4. bBavarian Longitudinal Study, also known as BEST (Bayerische Entwicklungsstudie) (Germany, born 1985).
  5. cEPICure Cohort (UK & The Republic of Ireland, born 1995).
  6. d[Preterm Birth and Early Life Programming of Adult Health and Disease] Ennenaikainen syntymä, raskaus ja lapsen terveys aikuisiässä, Northern Finland, born 1985–1989).
  7. eHelsinki Study of Very Low Birth Weight Adults (Helsinki, Finland, born 1978–1985).
  8. fNorges Teknisk-Naturvitenskapelige Universitet [Norwegian University of Science and Technology] Low Birth Weight Life (Trondheim, Norway, born 1986–1988).
  9. gNew Zealand Very Low Birth Weight 1986 Cohort (New Zealand, born 1986).
  10. hVictorian Infant Collaborative Study (Victoria, Australia, born 1991–1992).
  11. iAll live births in Finland between 01/01/1987 and 31/12/1998.
  12. jFor the population-based register-linkage study age is at death, emigration or end of follow-up (31/12/2016).
  13. kFor the population-based register-linkage study highest education is maternal education.
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