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Abstract
Background Current literature shows a distinct peak in asthma exacerbations in September among children, attributing it in part to their return to school and the spread of viral agents accompanying this. There is comparatively little recent research into the trends in adults, however. This study examines seasonal variations in asthma exacerbations in a population of adults with asthma from the community.
Methods The study population was identified from The Health Improvement Network database of anonymised GP records. Patients were between 16–40 years and had a prescription for asthma treatment during a qualification window of 1998–2000. Current analyses are restricted to patients with at least 5 years of data available pre-qualification. In this instance we defined exacerbations as acute oral prednisolone prescriptions. The daily total number of exacerbations was calculated from 01-01-1999 to 31-12-2003. To explore the potential relationship between exacerbations and co-morbidities, we also explored antibiotic and antiviral prescriptions as well as treatments for seasonal allergic rhinitis in this cohort.
Results 38,439 patients with current asthma were identified. Prednisolone exacerbations decreased from the beginning of the year until summer, at which point there was a peak in June (Figure: solid line). They then increased in autumn peaking at the end of October, then increasing throughout winter. During the summer there was a similar peak observed in both prednisolone exacerbations and seasonal allergic rhinitis prescriptions in this cohort. From September through to May the trends observed in prednisolone exacerbations were similar to those seen in antiviral and antibiotic prescriptions.
Conclusions Within the seasonal trends observed, there appears to be some correlation between the summer peak in exacerbations and seasonal allergic rhinitis prescriptions. There are also similarities seen in exacerbations during the beginning and end of the year and antibiotic and antiviral prescriptions. These findings suggest that infections and seasonal allergic rhinitis might be drivers for asthma exacerbations in adults.