Rhinitis and onset of asthma: a longitudinal population-based study.

Background: A close relation between asthma and allergic rhinitis has been reported by several epidemiological and clinical studies. However, the nature of this relation remains unclear. We used the follow-up data from the European Community Respiratory Health Survey to investigate the onset of asthma in patients with allergic and non-allergic rhinitis during an 8.8-year period.

Methods: We did a longitudinal population-based study, which included 29 centres (14 countries) mostly in western Europe. Frequency of asthma was studied in 6461 participants, aged 20-44 years, without asthma at baseline. Incident asthma was defined as reporting ever having had asthma confirmed by a physician between the two surveys. Atopy was defined as a positive skin-prick test to mites, cat, Alternaria, Cladosporium, grass, birch, Parietaria, olive, or ragweed. Participants were classified into four groups at baseline: controls (no atopy, no rhinitis; n=3163), atopy only (atopy, no rhinitis; n=704), non-allergic rhinitis (rhinitis, no atopy; n=1377), and allergic rhinitis (atopy+rhinitis; n=1217). Cox proportional hazards models were used to study asthma onset in the four groups.

Findings: The 8.8-year cumulative incidence of asthma was 2.2% (140 events), and was different in the four groups (1.1% (36), 1.9% (13), 3.1% (42), and 4.0% (49), respectively; p<0.0001). After controlling for country, sex, baseline age, body-mass index, forced expiratory volume in 1 s (FEV(1)), log total IgE, family history of asthma, and smoking, the adjusted relative risk for asthma was 1.63 (95% CI 0.82-3.24) for atopy only, 2.71 (1.64-4.46) for non-allergic rhinitis, and 3.53 (2.11-5.91) for allergic rhinitis. Only allergic rhinitis with sensitisation to mite was associated with increased risk of asthma independently of other allergens (2.79 [1.57-4.96]).

Interpretation: Rhinitis, even in the absence of atopy, is a powerful predictor of adult-onset asthma.