Objectives: Increased bronchial responsiveness is a
feature of symptomatic asthma, and it predicts the onset of wheezing.
We have investigated the relationship between bronchial responsiveness
and age in a population sample with an age range of 45 to 86
Design: Cross-sectional population survey.
Setting: Population of Central Manchester, UK.
Participants: An age-stratified random sample of white
adults aged ≥ 45 years old and living in Central Manchester. They
were recruited from their primary care physician (general practitioner)
lists. Patients with confusion and patients who were housebound were
Measurements: Respondents to a mail
questionnaire were invited to attend a methacholine bronchial challenge
performed using the Newcastle dosimeter method. Respondents with
ischemic heart disease or respondents taking oral steroids,β
-blockers, or anticholinergic medication were excluded.
Results: Of the 783 subjects contacted, 92.3% of the
subjects responded, and 508 subjects returned enough information for us
to deduce their suitability for the bronchial challenge. Of the 395
suitable subjects, 247 subjects participated (62.5% of those invited;
31.5% of the study population), and 208 participants completed the
bronchial challenge. Participants were slightly younger than
nonparticipants, but they were otherwise representative of the
population. Increased bronchial responsiveness (provocative dose of
methacholine causing a 20% fall in FEV1 ≤ 200 μg) was
present in 71 (34.1%) participants. Stepwise multiple regression
analysis showed weak, independent, positive associations between
bronchial responsiveness and age, and between bronchial responsiveness
and the total immunoglobulin E level. There was an independent negative
relationship between bronchial responsiveness and the airways caliber
(expressed as standardized residuals;
R2 = 0.29).
have found a high prevalence of increased bronchial responsiveness in
this inner-city population of older adults. Bronchial responsiveness
showed a weak independent positive association with
DRS = dose-response slope; PD20 = provocative dose of a
substance causing a 20% fall in FEV1; SR = standardized