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. 2018 Apr 16;7(6):2665–2681. doi: 10.1002/cam4.1466

Table 3.

Association between acute lymphoblastic leukemia, farm residence, and contact with livestock and poultry in the first year of life, pooled analysis of 10 studies (1980–2013), children aged 1 to 14 years old, Childhood Leukemia International Consortium

Number of studies ALL Controls ORa 95% CI P
n % n %
Living on a farm (any definitions) 8b
No 3898 97 6343 97 1.00 Ref.
Yes 134 3 198 3 1.09 0.86, 1.36 0.48
Missing 113 105
Living on a farm in the first year of life 6c
No 2494 97 4361 97 1.00 Ref.  
Yes 79 3 140 3 0.93 0.70, 1.24 0.64
Missing 106 85
Contact with any livestock in the first year of life 7d
No 3193 98 5155 96 1.00 Ref.
Yes 79 2 219 4 0.65 0.50, 0.85 0.002
Missing 34 35
Contact with cattle 7d
No 3235 99 5227 97 1.00 Ref.
Yes 44 1 155 3 0.54 0.39, 0.77 0.0006
Missing 27 27
Contact with pigs 7d
No 3260 99 5316 99 1.00 Ref.
Yes 19 1 66 1 0.58 0.35, 0.98 0.04
Missing 27 27
Contact with sheep 6e
No 2996 99 4731 98 1.00 Ref.
Yes 44 1 104 2 0.68 0.47, 0.98 0.04
Missing 25 24
Contact with any livestock in the first year of life 6e
No 2968 98 4645 96 1.00 Ref. 0.02
Contact with cattle only 18 0.6 58 1.2 0.59 0.34, 1.01
Contact with pigs only 3 0.1 7 0.1 0.95 0.24, 3.74
Contact with sheep only 29 0.9 47 1.0 0.91 0.56, 1.46
Contact with at least two types of animals 18 0.6 71 1.5 0.44 0.26, 0.75
Missing 29 31
Contact with poultry in the first year of life 6e
No 2926 97 4584 95 1.00 Ref.
Yes 105 3 242 5 0.78 0.62, 1.00 0.05
Missing 34 33

ALL, acute lymphoblastic leukemia; AUS_ALL, Australian Study of Causes of Acute Lymphoblastic Leukemia in Children; CA_QCLS, Quebec Childhood Leukemia Study (Canada); CI, confidence interval; CR_CRCLS, Costa Rican Childhood Leukemia Study (Costa Rica); FR_ADELE, Adele Study (France); FR_ELECTRE, Electre Study (France); FR_ESCALE, Epidemiologic Study on Childhood Cancer and Leukemia (France); FR_ESTELLE, Epidemiologic Study on Childhood Cancer, Leukemia and lymphoma (France); GR_NARECHEM, Nationwide Registration for Childhood Hematological Malignancies (Greece); NZ_NZCCS, New Zealand Childhood Cancer Study (New Zealand); OR, odds ratio; US_NCCLS, Northern California Childhood Leukemia Study (United States).

a

Odds ratio and 95% confidence interval were estimated by unconditional logistic regression adjusted for child's age at reference date, child's sex, maternal age at child's birth, maternal educational level, and study of origin.

b

Eight studies (n = 4145 cases, n = 6646 controls): AUS_ALL, CA_QCLS, FR_ADELE, FR_ESCALE, FR_ESTELLE, GR_NARECHEM, NZ_NZCCS, US_NCCLS.

c

Six studies (n = 2679 cases, n = 4586 controls): CA_QCLS, FR_ADELE, FR_ESCALE, FR_ESTELLE, NZ_NZCCS, US_NCCLS.

d

Seven studies (n = 3306 cases, n = 5409 controls): CR_CRCLS, FR_ADELE, FR_ELECTRE, FR_ESCALE, FR_ESTELLE, GR_NARECHEM, NZ_NZCCS.

e

Six studies (n = 3065 cases, n = 4859 controls): FR_ADELE, FR_ELECTRE, FR_ESCALE, FR_ESTELLE, GR_NARECHEM, NZ_NZCCS.