Asthma by yaofenji

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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@soton.ac.uk
E&W consultation rates for
asthma (males) 1971-1991
100
 90
 80
 70
 60                                              1971
 50
                                                 1981
 40
                                                 1991
 30
 20
 10
  0
      0-4   5-14 15-24 25-44 45-64 65-74   >75
 E&W consultation rates for
asthma (females) 1971-1991
 80
 70
 60
 50
                                                 1971
 40
                                                 1981
 30                                              1991
 20
 10
 0
      0-4   5-14 15-24 25-44 45-64 65-74   >75
 UK Consultation rates for
 allergic rhinitis 1971-1991
600

500

400
                                                 1971
300
                                                 1981
200                                              1991

100

 0
      0-4   5-14 15-24 25-44 45-64 65-74   >75
       E&W consultation rates for
         asthma 1976-2000
1st or new episodes/week (per 100,000)
 160
 140
 120
 100                                              0-4
  80                                              5-14
  60                                              15+
  40
  20
   0
        76 78 80 82 84 86 88 90 92 94 96 98   0
 Possible causes of an Increase
  in the Prevalence of Asthma
• Labelling / Medical fashion
Allergic disease in Aberdeen children
    Ninan & Russell BMJ 1992;304:873-875


             1964       1989      RR

 Asthma      4.1%       10.2%     1.75

 Eczema      5.3%       12.0%     2.33

 Hay Fever 3.2%         11.9%     3.70
               40
               35
               30
Wheeze         25
(last 12 mo)   20                                              1995
               15                                              2002

               10
               5
               0
                    SE   Scotland      Wales      Isles

               30

               25
Asthma
               20
(lifetime)
               15                                              1995
                                                               2002
               10

               5

               0
                    SE   Scotland      Wales      Isles

                                    Anderson et al BMJ 2004; 328;1052-3
Asthma prevalence & health care
    use in Britain 1970-2000
            0-4     5-14    Adults

Prevalence -        x1.5    -

GP contact x10      x5      x3

Admissions x20      x10     x2-3

Mortality   Low & falling   variable
 Possible causes of an Increase
  in the Prevalence of Asthma
• Labelling / Medical fashion
• Allergy
    Making houses HDM-friendly
•   Bedroom & living room carpets
•   Central heating
•   More humidity
•   Soft furnishings
•   Fluffy toys
Prevalence of allergic disease
        in Australia
    Peat et al BMJ 1992;305:1326-9

                     1981       1991
Recent wheeze        17.5%      28.8%
Diagnosed asthma     9.0%       16.3%
Hay Fever            24.9%      46.7%
SOB on exertion      19.2%      20.3%
Allergy (HDM)        24.9%      24.5%
Allergy (GP)         28.8%      28.8%
     Allergen Avoidance
    Unanswered 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?
Prevalence of allergic sensitisation in Germany
       Nowak D et al ERJ 1996; 9:2541-2552

  Hamburg                Erfurt
  • commercial and       • industrial
    administrative
  • traffic ++           •   little traffic
  • prevailing W wind    •   low windspeed
  • mean SO2 31 mg/m3    •   mean SO2 264 mg/m3
  • mean TSP 53 mg/m3    •   mean TSP 137 mg/m3
  (1985-89 values)
  Prevalence of allergic sensitisation in
               Germany
    Nowak D et al ERJ 1996; 9:2541-2552
Hamburg               Erfurt
• 4,500 subjects      • 4,990 subjects
• 0.6% of total       • 5.8% of total
• 3.5% born outside   • 0.7% born outside
  Germany               Germany
• response rate 80%   • response rate 74%
        Age-dependent differences
          in allergic sensitisation
     Heinrich J et al Allergy 1998; 53:89-93
• ECRHS phase 2                   Hamburg   Erfurt

  data                    50

• Hamburg n= 972          40
• Erfurt      n= 726      30
• skin test to birch,     20
  grass, cat, moulds
                          10
  or house dust mite
• trend linked to early    0
                               1946-51 1952-61 1961-71
  life in new “Western”             Birth cohort
  setting
         Age-dependent differences
           in rhinitis prevalence
     Heinrich J et al Allergy 1998; 53:89-93
• ECRHS phase 1                   Hamburg   Erfurt

• Hamburg n= 3,153        30

• Erfurt      n= 3,254    25
                          20
• rhinitis prevalence
                          15
  (ex-questionnaire)
                          10
• possible cultural
                           5
  effect - do patients
                           0
  seek more help for           1946-51 1952-61 1961-71
  rhinitis in West?                 Birth cohort
Factors associated with living in Hamburg
      Nowak D et al ERJ 1996; 9:2541-2552

•   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
Prevalence of allergic sensitisation in Germany
      Nowak D et al ERJ 1996; 9:2541-2552

  • 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
       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
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 1976;37:91-100
Allergy skin reaction rates (%) in
    10/11 yr olds: urban-rural
 gradients apply to cat, not birch
         Sweden Sweden Poland    Estonia Estonia

         Rural   Urban   Konin   Tallinn   Tartu

 Any     24      35      13.7    14.3      8.3

 Cat     12.5    21      2.5     6.1       4.0

 Birch   10      12      2.2     2.6       2.3
      Why is there so much
            asthma?
• Two separate questions:

• Why do so many children start
  wheezing?

• Why don’t more of them grow out of it?
   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
       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
     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

								
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