Prevalence of nocturnal asthma in a general population sample: determinants and effect of aging.

Nocturnal asthma (NA) is important because of clinical and prognostic implications. Previous data on prevalence may be overestimated, because they are derived from selected series. Observations on monitoring of peak expiratory flow in elderly asthmatics suggested that prevalence of NA may increase with age. This study was designed to estimate the prevalence of NA-related symptoms in a sample drawn from a general population and evaluate the role of aging. Subjects (1,100, mean age 41.9, SD 22.8 years) were randomly selected from the lists of seven general practitioners. A questionnaire on nighttime and morning NA-associated symptoms was used and frequency of occurrence was rated as never, so…