title: Apparent but not real increase in asthma prevalence during the 1990s.
abstract: The authors investigated changes in asthma prevalence and perception of bronchoconstriction over 6 yrs in adults of Newcastle-upon-Tyne. Postal questionnaires were sent to 6,000 subjects aged 20-44 yrs in 1992-1993 and 1998-1999. Random samples of 600 responders had assessments of atopy, airway responsiveness, and their ability to perceive methacholine-induced bronchoconstriction. The prevalences of asthmatic symptoms, physician-diagnosis, and medication use increased by an average of 4.4%, particularly in subjects aged <30 yrs (8.7 versus 2.7). Atopy prevalence increased from 25% to 31% but atopics and nonatopics had similar mean changes in questionnaire data (5.2 versus 3.4). The probability of a positive methacholine test decreased as did the mean methacholine dose/response slope (0.00527 to 0.00379), indicating lower levels of airway responsiveness. This can be largely explained by an increase in use of inhaled corticosteroids (5.0-9.3%). The proportion of subjects perceiving bronchoconstriction during methacholine tests increased from 63 to 77%. The authors conclude that current changes in asthma epidemiology in adults may result from increased awareness of symptoms (and/or an increased willingness to report them), and from an increased willingness of physicians to make the diagnosis and prescribe treatment, not from increased disease prevalence.
authors.affiliation: Dept of Respiratory Medicine, Royal Victoria Infirmary, University of Newcastle-upon-Tyne, UK.
authors.forename: R
authors.initials: R
authors.lastname: Barraclough
authors.forename: G
authors.initials: G
authors.lastname: Devereux
authors.forename: D J
authors.initials: DJ
authors.lastname: Hendrick
authors.forename: S C
authors.initials: SC
authors.lastname: Stenton
mesh_terms: D000293:Adolescent; D000328:Adult; D017677:Age Distribution; D000368:Aged; D001249:Asthma / Q000175:diagnosis* / Q000453:epidemiology*; D001985:Bronchial Provocation Tests; D016009:Chi-Square Distribution; D002648:Child; D005260:Female; D006801:Humans; D016014:Linear Models; D016015:Logistic Models; D008297:Male; D016210:Methacholine Chloride / Q000494:pharmacology; D008875:Middle Aged; D011159:Population Surveillance; D015995:Prevalence; D011336:Probability; D012129:Respiratory Function Tests; D012307:Risk Factors; D012720:Severity of Illness Index; D017678:Sex Distribution; D011795:Surveys and Questionnaires; D006113:United Kingdom / Q000453:epidemiology
chemical_list: D016210:Methacholine Chloride