Eczema, birth order, and infection.
The association between infections occurring in the first 2 years of life and development of eczema was investigated in 1,782 control children from a national population-based case-control study in the United Kingdom conducted over the period 1991-1996. Dates of eczema and infectious diagnoses were ascertained from contemporaneously collected primary care records. Children diagnosed with eczema before the age of 2 years had more prior clinically diagnosed infections recorded than did children without eczema (rate ratio = 1.26, 95% confidence interval (CI): 1.18, 1.36). The difference in infection rates between children with and without eczema was apparent from birth and throughout the first 2 years of life. As expected, compared with children of second or higher birth order, those firstborn were at increased risk of eczema (p = 0.020); however, the relation between eczema and prior infection was evident only among children of second or higher birth order and not among firstborn children (rate ratio = 1.45, 95% CI: 1.32, 1.59, and rate ratio = 1.08, 95% CI: 0.98, 1.20, respectively). The authors' results are consistent with the notion that the association between birth order and eczema is unlikely to be attributable to variations in early infectious exposure.
Hughes
Ann Maree
AM
Epidemiology and Genetics Unit, Department of Health Sciences, University of York, Heslington, York, United Kingdom.
Crouch
Simon
S
Lightfoot
Tracy
T
Ansell
Pat
P
Simpson
Jill
J
Roman
Eve
E
D001722:Birth Order; D016022:Case-Control Studies; D004485:Eczema / Q000453:epidemiology / Q000209:etiology*; D005260:Female; D006801:Humans; D015994:Incidence; D007223:Infant; D007239:Infections / Q000150:complications*; D016015:Logistic Models; D008297:Male; D016012:Poisson Distribution