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Table 1 Characteristics of study participants in CHARGE through September 2011

From: Autism spectrum disorder, flea and tick medication, and adjustments for exposure misclassification: the CHARGE (CHildhood Autism Risks from Genetics and Environment) case–control study

 

Autism spectrum disorder

Typically developing

 

N (%)

N (%)

Imidacloprid usage (ever)

  

No

461 (79)

280 (79)

Yes

115 (20)

75 (21)

Missing

11 (2)

1 (0)

Imidacloprid usage (prenatal)

  

No

491 (84)

300 (84)

Yes - total

70 (12)

40 (11)

Yes – Consistent†

47 (8)

20 (6)

Yes – Occasional†

15 (3)

14 (4)

Missing

26 (4)

16 (4)

Maternal education

  

College degree

243 (41)

120 (34)

High school

88 (15)

54 (15)

Some college

256 (44)

182 (51)

Missing

0 (0)

0 (0)

Child’s age at interview

  

Mean

3.80

3.56

Standard deviation

0.81

0.81

Missing

0

0

Maternal race/ethnicity

  

Asian/Pacific Islander

46 (8)

25 (7)

Black

20 (3)

10 (3)

Multiracial

24 (4)

16 (4)

Native American/Alaskan

3 (1)

1 (0)

Other race

0 (0)

1 (0)

White/Hispanic

140 (24)

69 (19)

White/Non-Hispanic

330 (56)

221 (62)

Missing

24 (4)

13 (4)

Child’s sex

  

Male

497 (85)

295 (83)

Female

90 (15)

61 (17)

Missing

0 (0)

0 (0)

Parity

  

Primiparous

160 (27)

99 (28)

2

194 (33)

102 (29)

3

116 (20)

64 (18)

4

59 (10)

50 (14)

>4

51 (9)

38 (11)

Missing

7 (1)

3 (1)

Pet contact (prenatal)

  

No

168 (29)

97 (27)

Yes

272 (46)

196 (55)

Missing§

147 (25)

63 (18)

  1. † Consistent = reported imidacloprid use for every month of prenatal period; Occasional = reported only some months of use during prenatal period. Frequency is missing if exposure in any month is missing.
  2. ‡ Maternal race/ethnicity: single variable combining the two variables: race and ethnicity. Categories were hierarchical: race was assigned first; then among whites, was assigned as Hispanic or non-Hispanic.
  3. § 213 individuals missing prenatal pet contact information resulting from faulty skip pattern in phone interview software for some participants.