Sex Differences in Factors Associated with Childhood- and Adolescent-onset Wheeze

Rationale: Factors predicting the development of wheeze may differ between sexes and between childhood and adolescence.

Methods: A New Zealand birth cohort of 1,037 children was followed to age 26. For this analysis, those reporting recurrent wheezing at two or more assessments were classified as "wheezers." We examined risk factors for development of wheeze before age 10 (childhood) and subsequently (adolescent-onset) for males and for females separately using Cox regression modeling.

Results: Males more often developed childhood wheeze (p = 0.002) and females adolescent-onset wheeze (p < 0.001). Maternal atopy (asthma or hay fever) was a risk factor for childhood wheeze in both sexes (hazard ratio [HR], 1.48, p < 0.05 for males; HR, 2.37, p < 0.001 for females). Paternal atopy also influenced childhood wheeze, significantly for males (HR, 1.72; p = 0.01), and similarly but not significantly for females (HR, 1.70; p = 0.08). For adolescent-onset wheeze, neither maternal (HR, 1.41; p = 0.19) nor paternal history (HR, 0.73; p = 0.42) was a risk factor in males, but maternal history (HR, 2.08; p < 0.01) was a significant risk factor for females. When both age ranges were combined, providing greater power for analysis, paternal history was a stronger risk factor for wheeze in females (HR, 1.62; p = 0.02) than in males (HR, 1.35; p = 0.12).

Conclusion: The influence of parental atopy on the development for wheeze differs between males and females and between childhood- and adolescent-onset wheeze.