title: Intergenerational 20 year trends in the prevalence of asthma and hay fever in adults: the Midspan family study surveys of parents and offspring.
abstract: OBJECTIVE
  To estimate trends between 1972-6 and 1996 in the prevalences of asthma and hay fever in adults.
  
  
  METHODS
  Two epidemiological surveys 20 years apart. Identical questions were asked about asthma, hay fever, and respiratory symptoms at each survey.
  
  
  METHODS
  Renfrew and Paisley, two towns in the west of Scotland.
  
  
  METHODS
  1,477 married couples aged 45-64 participated in a general population survey in 1972-6; and 2,338 offspring aged 30-59 participated in a 1996 survey. Prevalences were compared in 1,708 parents and 1,124 offspring aged 45-54.
  
  
  METHODS
  Prevalences of asthma, hay fever, and respiratory symptoms.
  
  
  RESULTS
  In never smokers, age and sex standardised prevalences of asthma and hay fever were 3.0% and 5.8% respectively in 1972-6, and 8.2% and 19. 9% in 1996. In ever smokers, the corresponding values were 1.6% and 5.4% in 1972-6 and 5.3% and 15.5% in 1996. In both generations, the prevalence of asthma was higher in those who reported hay fever (atopic asthma). In never smokers, reports of wheeze not labelled as asthma were about 10 times more common in 1972-6 than in 1996. With a broader definition of asthma (asthma and/or wheeze), to minimise diagnostic bias, the overall prevalence of asthma changed little. However, diagnostic bias mainly affected non-atopic asthma. Atopic asthma increased more than twofold (prevalence ratio 2.52 (95% confidence interval 1.01 to 6.28)) whereas the prevalence of non-atopic asthma did not change (1.00 (0.53 to 1.90)).
  
  
  CONCLUSIONS
  The prevalence of asthma in adults has increased more than twofold in 20 years, largely in association with trends in atopy, as measured indirectly by the prevalence of hay fever. No evidence was found for an increase in diagnostic awareness being responsible for the trend in atopic asthma, but increased awareness may account for trends in non-atopic asthma.
authors.affiliation: Department of General Practice, University of Glasgow, Glasgow G12 0RR. maknupton@aol.com
authors.forename: M N
authors.initials: MN
authors.lastname: Upton
authors.forename: A
authors.initials: A
authors.lastname: McConnachie
authors.forename: C
authors.initials: C
authors.lastname: McSharry
authors.forename: C L
authors.initials: CL
authors.lastname: Hart
authors.forename: G D
authors.initials: GD
authors.lastname: Smith
authors.forename: C R
authors.initials: CR
authors.lastname: Gillis
authors.forename: G C
authors.initials: GC
authors.lastname: Watt
mesh_terms: D000328:Adult; D000368:Aged; D001249:Asthma / Q000453:epidemiology*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D015995:Prevalence; D012135:Respiratory Sounds / Q000209:etiology; D006255:Rhinitis, Allergic, Seasonal / Q000453:epidemiology*; D012606:Scotland / Q000453:epidemiology; D012907:Smoking / Q000453:epidemiology; D012923:Social Class