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Intergenerational 20 year trends in the prevalence of asthma and hay fever in adults: the Midspan family study surveys of parents and offspring

BMJ 2000; 321 doi: https://doi.org/10.1136/bmj.321.7253.88 (Published 08 July 2000) Cite this as: BMJ 2000;321:88
  1. Mark N Upton, Wellcome Trust research training fellow in clinical epidemiologya (marknupton{at}aol.com),
  2. Alex McConnachie, statisticiana,
  3. Charles McSharry, principal scientistb,
  4. Carole L Hart, statisticianc,
  5. George Davey Smith, professor of clinical epidemiologyd,
  6. Charles R Gillis, professor, west of Scotland cancer surveillance unitc,
  7. Graham C M Watt, professor of general practicea
  1. a Department of General Practice, University of Glasgow, Glasgow G12 0RR
  2. b Department of Immunology, Western Infirmary, Glasgow G11 6NT
  3. c Department of Public Health, University of Glasgow, Glasgow G12 8RZ
  4. d Department of Social Medicine, University of Bristol, Bristol BS8 2PR
  1. Correspondence to: M N Upton, Thornaby and Barwick Medical Group, The Health Centre, Thornaby, Cleveland TS17 0BZ

    Abstract

    Objective: To estimate trends between 1972–6 and 1996 in the prevalences of asthma and hay fever in adults.

    Design: Two epidemiological surveys 20 years apart. Identical questions were asked about asthma, hay fever, and respiratory symptoms at each survey.

    Setting: Renfrew and Paisley, two towns in the west of Scotland.

    Subjects: 1477 married couples aged 45–64 participated in a general population survey in 1972-6; and 2338 offspring aged 30–59 participated in a 1996 survey. Prevalences were compared in 1708 parents and 1124 offspring aged 45-54.

    Main outcome measures: 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)).

    Conclusion: 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.

    Footnotes

    • Funding: MNU and the fieldwork were supported by the Wellcome Trust. AMcC and some of the nurses were supported by the NHS Research and Development programme.

    • Competing interests: None declared.

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