Background: Allergic rhinitis and sinus symptoms are common in persons with asthma. Studies concerning the effects of sinusitis and allergic rhinitis on asthma severity have had inconsistent findings: some have shown an increased risk of severe asthma, whereas others have not. These inconsistencies may be a result of the variation of asthma severity among study participants. Dixon and colleagues evaluated the impact of self-reported allergic rhinitis and sinusitis on asthma.

The Study: The study population consisted of persons with asthma enrolled in two clinical trials. The first trial evaluated the effect of influenza vaccination on each participant's asthma control. The second evaluated low-dose theophylline as an additional therapy for severe asthma. Information about participants' allergic rhinitis and sinusitis symptoms was collected in each study using a structured questionnaire. Asthma severity was established using the Asthma Symptom Utility Index, peak flow measurement, and spirometry. Participants were evaluated for acute asthma exacerbations.

Results: The combined study population was 2,519; more than 70 percent of participants reported allergic rhinitis or sinusitis. The conditions were more likely to occur in women, those with gastroesophageal reflux disease, and whites. In one of the studies, participants with allergic rhinitis and sinusitis had an increase in asthma symptoms and a trend toward more sleep disturbances. Patients with allergic rhinitis had higher baseline lung functions compared with those who did not have allergic rhinitis, but asthma exacerbations were similar for both groups. Those with sinusitis had lung functions similar to those who did not have sinusitis. In one trial, participants with severe asthma and sinusitis had increased exacerbations of asthma.

Conclusion: The authors conclude that allergic rhinitis and sinusitis correlated with more severe asthma symptoms in patients with poorly controlled asthma. In addition, these conditions were associated with more exacerbations but not with low lung function in this population. Controlling symptoms related to allergic rhinitis and sinusitis may improve symptoms related to asthma.