Early-life risk factors and allergic rhinitis: Comparing European and US data

Allergic rhinitis has been shown to affect 3 % to 19 % of subjects in various epidemiologic studies of different populations. Eighty percent of those with allergic rhinitis experience symptoms by the age of 20 years, and 40 % have symptoms by the age of 6 years.1 Allergic rhinitis is a substantial burden on both adult and pediatric patients, not only because of the bothersome physical symptoms but also because of the emotional and social effects.2, 3 It is also closely linked with the development of asthma.4 Investigation into early-childhood factors influencing the development of allergic rhinitis raises the possibility of altering its natural history and decreasing this significant negative effect. In this issue of the Journal, Matheson et al5 present data from the European Community Respiratory Health Study II (ECRHS II) regarding the association between the incidence of rhinitis and early-life exposures. The most striking findings of this study were that a number of early-life exposures seem to be protective against rhinitis. The incidence of rhinitis decreased with increased number of siblings, bedroom sharing with older children before the age of 5 years, exposure to pets before the age of 5 years, and farm upbringing, regardless of atopy status. Risk factors for rhinitis included maternal smoking in pregnancy an