Early-life risk factors and incidence of rhinitis: Results from the European Community Respiratory Health Study - an international population-based cohort study.

BACKGROUND: Rhinitis is an increasingly common condition with a heavy health care burden, but relatively little is known about its risk factors. OBJECTIVE: To examine the association between early-life factors and the development of rhinitis in the European Community Respiratory Health Study (ECRHS). METHODS: In 1992-1994, community-based samples of 20-44-year-old people were recruited from 48 centers in 22 countries. On average, 8.9 years later, 28 centers reinvestigated their samples. Onset of rhinitis was reported by 8486 participants in interviewer-led questionnaires. Cox regression was used to assess independent predictors of rhinitis at ages ≤5, 6-10, 11-20, and ≥21 years. RESULTS: The crude lifelong incidence of rhinitis was 7.00/1000/year (men) and 7.95/1000/year (women) (P = .002). Women developed less rhinitis in later childhood (hazard ratios [HR], 0.63; 95% CI, 0.47-0.85) and more rhinitis in adulthood (HR, 1.36; 95% CI, 1.11-1.66) than did men. In atopic subjects, siblings were associated with lower risk of rhinitis throughout life (pooled HR, 0.94; 95% CI, 0.91-0.98 per 1 sibling). Early contact with children in the family or day care was associated with less incidence of rhinitis, predominantly before age 5 years (HR, 0.84; 95% CI, 0.72-0.99). Early childhood pets or growing up on a farm was associated with less incidence of rhinitis in adolescence (HR, 0.50; 95% CI, 0.37-0.68). Combining these factors showed evidence of a dose-response relationship (trend P = .0001). CONCLUSIONS: Gender is a strong risk factor for rhinitis, with age patterns varying according to atopic status. Protective effects of early contact with children and animals were suggested for incident rhinitis, with risk patterns varying by age window and atopic status