Symptoms and diagnosis of asthma in a general population – longitudinal results from the SHIP database.

Background: Against the background of an increasing prevalence of allergies, the epidemiology of asthma in relation to age is still a matter of debate. To further clarify the prevalence of asthma, asthmatic symptoms, and their change over time within a population sample, we analyzed longitudinal data from the Study of Health in Pomerania (SHIP).
Methods: Standardized questionnaires for asthma and asthmatic symptoms were available in 4310 individuals aged 20–79 years [corrected]. The population sample underwent a 5-year follow-up with 3300 subjects reexamined. The questionnaire evaluated estimates to describe the prevalence in wheeze, chest tightness, shortness of breath, coughing, nocturnal symptoms, and asthma attacks in the past 12 months, current medications, current asthma, and nasal allergies at baseline and its longitudinal net change.
Results: The prevalence of current asthma at the baseline study was 1.8% [95% confidence interval (CI 1.4–2.2)], those of nasal allergies 16.7% (95% CI 15.6–17.9). Sixteen percent of asthmatic individuals were not medically treated. The net changes in asthmatic symptoms per 60 months of follow-up ranged between a decrease by 2.0% (chest tightness at night) and an increase by 1.2% (nocturnal attack of coughing). The proportions of subjects with current asthma remained unchanged. The prevalence of current asthma and symptoms was higher in young individuals, whereas the net change over time was slightly increasing at the age of 36 and above.
Conclusion: Despite the fact of a high prevalence of subjects complaining of nasal allergies, the overall prevalence of current asthma remained low over time. The prevalence in asthma and asthmatic symptoms as well as its net changes over 5 years were age dependent.