Asthma

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Asthma Allergies Current Trends
Relationship to Housing

• Prof Anthony Frew
• Allergy Respiratory Medicine
• University of Southampton
• E-mail A.J.Frew_at_soton.ac.uk

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EW consultation rates for asthma (males)
1971-1991
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EW consultation rates for asthma (females)
1971-1991
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UK Consultation rates for allergic rhinitis
1971-1991
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EW consultation rates for asthma 1976-2000
1st or new episodes/week (per 100,000)
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Possible causes of an Increasein the Prevalence
of Asthma

• Labelling / Medical fashion

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Allergic disease in Aberdeen children Ninan
Russell BMJ 1992304873-875
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Wheeze (last 12 mo)
Asthma (lifetime)
Anderson et al BMJ 2004 3281052-3
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Asthma prevalence health care use in Britain
1970-2000
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Possible causes of an Increasein the Prevalence
of Asthma

• Labelling / Medical fashion
• Allergy

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Making houses HDM-friendly

• Bedroom living room carpets
• Central heating
• More humidity
• Soft furnishings
• Fluffy toys

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Prevalence of allergic diseasein AustraliaPeat
et al BMJ 19923051326-9
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Allergen AvoidanceUnanswered Questions

• What degree of allergen avoidance is needed for
  clinical improvement?
• What is best way to achieve this?
• How much benefit can be achieved? (symptom
  control, drug reduction etc)
• Economics? (cost-benefit etc)
• Should NHS/3rd party payers foot bill?

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Prevalence of allergic sensitisation in
GermanyNowak D et al ERJ 1996 92541-2552

• Hamburg
• commercial and administrative
• traffic
• prevailing W wind
• mean SO2 31 mg/m3
• mean TSP 53 mg/m3
• (1985-89 values)

• Erfurt
• industrial
• little traffic
• low windspeed
• mean SO2 264 mg/m3
• mean TSP 137 mg/m3

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Prevalence of allergic sensitisation in
GermanyNowak D et al ERJ 1996 92541-2552

• Hamburg
• 4,500 subjects
• 0.6 of total
• 3.5 born outside Germany
• response rate 80

• Erfurt
• 4,990 subjects
• 5.8 of total
• 0.7 born outside Germany
• response rate 74

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Age-dependent differencesin allergic
sensitisationHeinrich J et al Allergy 1998
5389-93

• ECRHS phase 2 data
• Hamburg n 972
• Erfurt n 726
• skin test to birch, grass, cat, moulds or house
  dust mite
• trend linked to early life in new Western
  setting

Birth cohort
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Age-dependent differencesin rhinitis
prevalenceHeinrich J et al Allergy 1998 5389-93

• ECRHS phase 1
• Hamburg n 3,153
• Erfurt n 3,254
• rhinitis prevalence (ex-questionnaire)
• possible cultural effect - do patients seek more
  help for rhinitis in West?

Birth cohort
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Factors associated with living in HamburgNowak D
et al ERJ 1996 92541-2552

• fewer siblings
• history of asthma in siblings (not parents)
• history of atopy in parents and siblings
• passive smoking
• older houses single family houses
• not using open fires or gas cooking
• fitted carpets, mildew, cat in house
• slightly less likely to sleep with windows open
  in winter

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Prevalence of allergic sensitisation in
GermanyNowak D et al ERJ 1996 92541-2552

• Sensitisation is more frequent in West
• Principal risk factors for atopy
• male, sleeping with windows closed
• Principal risk factors for NSBR
• female, siblings with asthma
• BUT E-W difference in NSBR cannot be explained
  by the known risk factors assessed in this survey

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Infections Allergies

• URTI in infancy protect against allergy
• more siblings ? more viral infections
• reduced risk of atopy
• but in established asthma
• URTI are major cause of exacerbations
• esp in children 80 of attacks

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Allergy the price of affluence?

• Atopic disease is the price paid by some members
  of the affluent classes for their relative
  freedom from disease
• Annals of Allergy 19763791-100

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Allergy skin reaction rates () in 10/11 yr
olds urban-rural gradients apply to cat, not
birch
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Why is there so much asthma?

• Two separate questions
• Why do so many children start wheezing?
• Why dont more of them grow out of it?

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Outcome of early wheeze

• Wheezing up to age 18/12 unrelated to risk of
  developing atopy by age 7 years
• risks diverge thereafter
• atopy ?? risk of persistence

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Does asthma go away?

• wheeze before 3 years does not predict subsequent
  asthma
• 2/3 children with asthma at 10 lose it by 18
• early onset asthma is more likely to persist
• boys are more likely than girls to lose their
  asthma (because of differential lung growth)
• inflammation may persist without symptoms

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Asthma Epidemiology Summary

• Causation is complex
• Only environmental factors can account for speed
  of change
• Increase is likely to have different aetiological
  factors in different countries
• Epidemiological studies suggest that changes in
  housing may contribute to level of sensitisation
  to domestic allergens