Opposing effects of cat and dog ownership and allergic sensitization on eczema in an atopic birth cohort.
OBJECTIVE
To examine risk factors for eczema at age 4 years.


METHODS
Beginning at 1 year of age, infants of atopic parents (n = 636) had annual clinical evaluations and skin prick tests (SPTs) to 15 aeroallergens and milk and egg. Parents completed validated surveys on eczema and environmental exposures. House dust samples were evaluated for allergens and endotoxin. Eczema was defined as a parental report of scratching, and redness, "raised bumps," or dry skin/scaling for 6 of the last 12 months.


RESULTS
At age 4 years, a total of 90 children (14%) had eczema. Not having a dog before 1 year of age and being dog SPT+ at 1, 2, or 3 years of age conferred a 4-fold higher risk for eczema at age 4 years (adjusted odds ratio [aOR] = 3.9 [1.6-9.2]; P = .002). Among dog owners, however, dog SPT+ was not associated with significantly increased risk (aOR 1.3 [0.3-6.8]; P = .8). Among children with cats before 1 year of age, cat SPT+ conferred significantly increased risk for eczema (aOR = 13.3 [3.1-57.9]; P < .001). Among non-cat owners, cat SPT+ was not associated with increased risk (aOR = 1.1 [0.5-2.7]; P = .8).


CONCLUSIONS
Dog ownership significantly reduced the risk for eczema at age 4 years among dog-sensitized children, cat ownership combined with cat sensitization significantly increased the risk.
Epstein
Tolly G
TG
Department of Medicine, Division of Immunology, University of Cincinnati, Cincinnati, OH, USA.
Bernstein
David I
DI
Levin
Linda
L
Khurana Hershey
Gurjit K
GK
Ryan
Patrick H
PH
Reponen
Tiina
T
Villareal
Manuel
M
Lockey
James E
JE
Lemasters
Grace K
GK
D000367:Age Factors; D000485:Allergens; D000704:Analysis of Variance; D000818:Animals; D000829:Animals, Domestic / Q000276:immunology*; D002415:Cats; D002675:Child, Preschool; D015331:Cohort Studies; D016001:Confidence Intervals; D003876:Dermatitis, Atopic / Q000175:diagnosis / Q000453:epidemiology / Q000235:genetics / Q000276:immunology*; D004285:Dogs; D004485:Eczema / Q000453:epidemiology / Q000235:genetics / Q000276:immunology*; D004781:Environmental Exposure / Q000009:adverse effects*; D005260:Female; D020022:Genetic Predisposition to Disease; D006801:Humans; D007114:Immunization; D015994:Incidence; D007223:Infant; D007231:Infant, Newborn; D008137:Longitudinal Studies; D008297:Male; D016017:Odds Ratio; D011379:Prognosis; D018570:Risk Assessment; D012882:Skin Tests
D000485:Allergens