title: Day-care, early common infections and childhood acute leukaemia: a multicentre French case-control study.
abstract: We conducted a case-control study to investigate the role of early infections in the aetiology of childhood acute leukaemias. The study included 280 incident cases (240 acute lymphoblastic leukaemia and 40 acute non-lymphoblastic leukaemia) and 288 hospital controls, frequency matched by age, gender, hospital, catchment area of the hospital and ethnic origin. Data were obtained from standardised face-to-face interviews of the mothers. The interviews included questions on early common infections, day-care attendance, breast-feeding, birth order and infantile diseases. Odds ratios were estimated using an unconditional regression model including the stratification variables, parental socio-economic status and perinatal characteristics. Birth order was not associated with childhood leukaemia (acute lymphoblastic or acute non-lymphoblastic). A statistically-significant inverse association was observed between childhood leukaemia and day-care attendance (odds ratio=0.6, 95% Confidence Interval=(0.4-1.0)), repeated early common infections (> or = 4 per year before age two, odds ratio=0.6 (0.4-1.0)), surgical procedures for ear-nose-throat infections before age two (odds ratio=0.5 (0.2-1.0)) and prolonged breast-feeding (> or = 6 months, odds ratio=0.5 (0.2-1.0)). In the multivariate model including day-care attendance, early common infections and breast-feeding, results concerning breast-feeding remained unchanged. A statistically significant interaction between day-care attendance and repeated early common infections was observed. When the interaction was taken into account, the simple effects of day-care and early common infections disappeared (odds ratio=1.1 (0.5-2.3) and odds ratio=0.8 (0.5-1.3), respectively) while the joint effect of day-care attendance and early common infections was negatively associated with childhood leukaemia (odds ratio=0.3 (0.1-0.8)). All the above associations were observed both for acute lymphoblastic leukaemia and acute non-lymphoblastic leukaemia. Our results support Greaves' hypothesis, even though they are not specific of common leukaemia.
authors.affiliation: Institut National de la Santé et de la Recherche Médicale, Inserm U170, 16 avenue Paul Vaillant Couturier, 94807 Villejuif, France.
authors.forename: F
authors.initials: F
authors.lastname: Perrillat
authors.forename: J
authors.initials: J
authors.lastname: Clavel
authors.forename: M F
authors.initials: MF
authors.lastname: Auclerc
authors.forename: A
authors.initials: A
authors.lastname: Baruchel
authors.forename: G
authors.initials: G
authors.lastname: Leverger
authors.forename: B
authors.initials: B
authors.lastname: Nelken
authors.forename: N
authors.initials: N
authors.lastname: Philippe
authors.forename: G
authors.initials: G
authors.lastname: Schaison
authors.forename: D
authors.initials: D
authors.lastname: Sommelet
authors.forename: E
authors.initials: E
authors.lastname: Vilmer
authors.forename: D
authors.initials: D
authors.lastname: Hémon
mesh_terms: D001942:Breast Feeding; D016022:Case-Control Studies; D002648:Child; D002656:Child Day Care Centers; D002675:Child, Preschool; D005260:Female; D005602:France / Q000453:epidemiology; D006801:Humans; D007223:Infant; D007231:Infant, Newborn; D007239:Infections; D015470:Leukemia, Myeloid, Acute / Q000453:epidemiology / Q000209:etiology* / Q000517:prevention & control*; D008297:Male; D016017:Odds Ratio; D054198:Precursor Cell Lymphoblastic Leukemia-Lymphoma / Q000453:epidemiology / Q000209:etiology* / Q000517:prevention & control*; D012307:Risk Factors