Table 1 Demographics and proportion of children diagnosed with ADHD and ASD born between 2008 and 2012 in the Republic of Korea (n, %).

From: Association between birth weight and neurodevelopmental disorders assessed using the Korean National Health Insurance Service claims data

  

Total

 < 1.0 kg

1.0–1.4 kg

1.5–1.9 kg

2.0–2.4 kg

2.5–4.0 kg

 > 4.0 kg

P value

Birth yeara

2008

413,756 (100)

379 (0.1)

1666 (0.4)

3411 (0.8)

14,069 (3.4)

383,565 (92.7)

10,666 (2.6)

 < 0.001

2009

403,475 (100)

448 (0.1)

1637 (0.4)

3321 (0.8)

13,818 (3.4)

374,374 (92.8)

9877 (2.5)

 

2010

431,678 (100)

523 (0.1)

1651 (0.4)

3677 (0.9)

14,862 (3.4)

400,545 (92.8)

10,420 (2.4)

 

2011

438,828 (100)

557 (0.1)

1686 (0.4)

3706 (0.8)

15,960 (3.6)

407,290 (92.8)

9629 (2.2)

 

2012

455,915 (100)

605 (0.1)

1761 (0.4)

4105 (0.9)

16,918 (3.7)

422,279 (92.6)

10,247 (2.3)

 

Sex

Female

1,040,430 (48.5)

1396 (55.6)

4204 (50.0)

9206 (50.5)

41,134 (54.4)

966,645 (48.6)

17,845 (35.1)

 < 0.001

Income

Medical aid

11,872 (0.6)

20 (0.8)

69 (0.8)

138 (0.8)

580 (0.8)

10,700 (0.5)

365 (0.7)

 < 0.001

1st

233,822 (10.9)

276 (11.0)

942 (11.2)

2121 (11.6)

8593 (11.4)

215,988 (10.9)

5902 (11.6)

 

2nd

488,349 (22.8)

540 (21.5)

1941 (23.1)

4123 (22.6)

17,342 (22.9)

452,290 (22.8)

12,113 (23.8)

 

3rd

842,080 (39.3)

1,034 (41.2)

3250 (38.7)

6850 (37.6)

28,934 (38.3)

782,452 (39.4)

19,560 (38.5)

 

4th (highest)

567,529 (26.5)

642 (25.6)

2199 (26.2)

4988 (27.4)

20,178 (26.7)

526,623 (26.5)

12,899 (25.4)

 

Congenital or perinatal diseases

Yes

479,204 (22.4)

2276 (90.6)

6838 (81.4)

13,476 (73.9)

30,795 (40.7)

413,657 (20.8)

12,162 (23.9)

 < 0.001

ADHDb

Yes

27,008 (2.2)

63 (4.7)

186 (3.8)

346 (3.3)

1219 (2.9)

24,412 (2.1)

782 (2.5)

 < 0.001

 

Diagnosis age [Mean (S.D.)]

7.1 (1.6)

7.0 (1.8)

7.2 (1.6)

7.0 (1.6)

7.0 (1.6)

7.1 (1.6)

7.1 (1.6)

0.655

Medication

12,880 (1.0)

29 (2.2)

87 (1.8)

177 (1.7)

591 (1.4)

11,629 (1.0)

367 (1.2)

 < 0.001

ASD

Yes

14,394 (0.7)

190 (7.6)

355 (4.2)

450 (2.5)

921 (1.2)

12,085 (0.6)

393 (0.8)

 < 0.001

 

Diagnosis age [Mean (S.D.)]

3.8 (2.2)

2.1 (2.1)

1.9 (2.2)

2.2 (2.2)

3.1 (2.3)

4.0 (2.1)

 4.1 (2.0)

 < 0.001

Total

2,143,652 (100)

2512 (100)

8401 (100)

18,220 (100)

75,627 (100)

1,988,053 (100)

50,839 (100)

  
  1. ADHD attention-deficit/hyperactivity disorder, ASD autism spectrum disorder, S.D. standard deviation.
  2. aThe proportion by birth weight group was calculated using the annual number of births as the denominator.
  3. bThe analysis of ADHD included children born between 2008 and 2010, taking the average age at ADHD diagnosis (n = 1,248,909) into account.
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