(HealthDay News) – For infants with lower respiratory tract infection (LRTI) with a family history of atopy, secondhand smoke (SHS) exposure is associated with a longer hospital length of stay, according to a study published in the June issue of the Annals of Asthma, Allergy & Immunology.

Meghan Lemke, MD, from the Vanderbilt University School of Medicine in Nashville, TN, and colleagues conducted a cross-sectional analysis of 451 mother-infant dyads enrolled during 2004–2008 during an infant LRTI. The authors sought to examine whether infants with a familial atopic predisposition were more susceptible to the adverse effects of SHS.

The researchers found that SHS exposure was noted in 57% of the infants; 36% had a mother with atopic disease and 68% had familial atopy. There was no difference seen in the bronchiolitis severity score and hospital length of stay with SHS exposure stratified according to maternal atopic disease. In those with, but not in those without, familial atopy, there was a significant difference in hospital length of stay by SHS exposure, in bivariate analysis. For infants with familial atopy, the length of stay was significantly increased by 23% for infants with SHS exposure, in multivariate analysis.

“We found that in infants with familial atopy, SHS exposure was associated with a longer length of infant hospital stay for LRTI, which was not the case in those without this family history,” the authors write. “Future longitudinal investigations will be able to assess the consequences of these findings with subsequent asthma outcomes in the children.”

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