Practical Issues in Asthma Prevention

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Practical Issues in Asthma Prevention

• Dr Marie Wheeler
• General Paediatrician
• Cheltenham General Hospital/Gloucestershire
  Hospitals NHS Trust

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Outline of discussion

• Asthma and its prevalence
• Primary and secondary prevention
• (Diet, House Dust Mites, pets, smoking)
• Targeting all this advice .????
• Take home messages !!

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Asthma in Children

• Accurate diagnosischallenge in children.
• Education, Education ,Education.
• Asthma guidelines-British Thoracic Society/SIGN
  2005.
• Compliance and more education.
• Advice re. primary and secondary prevention.

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Asthma and Allergy

• 1/3 of 4 year olds with persistent wheeze are
  sensitive to at least one common aeroallergen.
• In older children asthma closely associated with
  allergy with approx. 2/3 affected.

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• British Medical Journal March 2005.

New episodes halved among the 5 to 24 years age
group. The issue does not indicate any
possible reasons for this.
New cases of asthma in children fall by two
thirds. The number of new cases of asthma fell
significantly in England and Wales between
1996 and 2003, with the number in children
falling the most, the latest issue of Social
Trends says.
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International Study of Asthma and Allergies in
childhood(ISAAC)Burr

• 25,393 children in 93 schools.
• CULPRITS FOR WHEEZE
• Non-metropolitan areas.
• Active(10) or passive smoking(6.5).
• Presence of a furry pet(5) .
• Bottled gas, paraffin.-oxides of
  nitrogen

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Primary Prevention

• Breast feeding
• Smoking
• Allergen avoidance-HDM, Pets.

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Primary Prevention-Breastfeeding.

• 8,183 subjects over 4 years ( systematic and
  meta-analysis) shows protective effect against
  development in asthma (esp. if FH atopy)
  Gdalevich.
• ( A more recent study showed an increase at 6
  years.)Wright
• Breast feeding should be encouraged, its benefits
  include a protective effect in relation to early
  life wheezing ( BTS and SIGN guidelines)

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Other milks

• Protein hydrolysate as a supplement or
  alternative for children who cannot breast feed
  seems to provide protection.

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Smoking
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Primary Prevention-Smoking

• Pregnancy smoking affects infants airway function
  with increased airway resistance at 4 weeks
  Young.
• Increased risk of wheeze is associated with
  smoking in pregnancy and maternal postnatal
  smoking.

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Smoking

• In- utero exposure seems to have more impact on
  childhood lung functionGilliland
• than post natal smoking.
• .

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Smoking

• Consistent odds ratio for respiratory illness 1.2
  to 1.6 for either parent smokingCook.
• Odds higher for preschool than school age.
• Significant effects from paternal smoking too.

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Smoking

• Odds ratio for recurrent or persistent bronchial
  obstruction in first 2 years of life highest for
  maternal daily smoking compared with
  socio-economic factors and atopy. Lodrup,
  Carlsen, Norway, 802 neonates

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Primary Prevention-Allergen Exposure

• Early exposure to allergens causes sensitization
  but development of asthma not demonstrated Lau.
• Considerations given to HDM prevention measures,
  diet, omega-3 fatty acids, probiotics, H 1
  antagonists, immunotherapy, ketotifen.

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House Dust Mite- (700,000 hits on google)

• Dermatophagoides pteronyssinus

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David Hide Asthma and Atopy Research
Centre-Isle of Wight 2003

• 58 infants, high risk group, breast fed or
  extensively hydrolysed formula and HDM prevention
  manoeuvres (acaricides and mattress covers).
• Age 8, current wheeze, nocturnal cough, asthma,
  and atopy all significantly reduced.
• Environmental manipulation decreased wheeze in
  first year of life in another high risk
  group.Custovic

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Study of Prevention of Allergy in Children in
Europe 2004Horak

• gt600 high risk newborns.
• One group- mite-impermeable mattress encasing and
  simple educational package on allergen avoidance.
  Control given basic allergy information.
• At age 2 no difference in HDM sensitization,
  nocturnal cough, wheezing.

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Childhood Asthma Prevention Study-Australia
2004Peat

• gt600 High Risk Children enrolled (antenatally)
• Given omega-3 fatty acids and HDM preventative
  measures.
• At age 3 significant reduction in cough and HDM
  sensitization but not wheeze.

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House Dust Mite Primary Prevention

• EVIDENCE CONVINCING?
• Yes or No??
• VOTE

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Pets

• Stay or go?
• Should we have pets before we have children?

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Pets..to stayto buy

• 400 children in Sweden Hesselmar 1999
• Children exposed to pets during the first year of
  life had less allergic rhinitis at age 7-9 and
  less asthma at age12-13.
• (Increasing no. of siblings associated with less
  too.)

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Pets.to go

• Prenatal manipulation in high risk for atopy,
  couples reduced some respiratory symptoms in the
  first year of life.
• Cat ownership was significantly associated with
  sensitization to cats (Custovic A et
  al,Manchester 2001)

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Pet avoidance Primary Prevention

• EVIDENCE CONVINCING
• Yes or No??
• VOTE

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Secondary Prevention

• House dust mites-Cochrane
  reviews..may!
• Pets
• Smoking

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House dust mites

• Likes Warmth
• Moisture
• Shedded human skin
• Carpets
• Soft furnishings
• Curtains

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House dust mites

• Dislikes Ventilation-dehumidifiers
• Damp dusting
• HEPA filters
• Freezers-Soft toys.
• Barrier covers
• High temp(gt50 degree c)
• A mite-killing material
• in a low-temp. wash
• Acaricidal powder

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House Dust Mites-Summary

• Restricting exposure significantly reduces asthma
  signs and symptoms ( less days of wheeze, reduced
  requirement for medication,fewer abnormal peak
  flows) in some studies.
• Highly significant reduction in IgE in some
  studies.

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Preventing the allergic march?

• Dust mite exposure with bedding encasement was
  reduced in infants with atopic dermatitis ( who
  were sensitized to egg, milk or soya bean but not
  to house dust mite)
• .after 1 year their specific IgE to HDM was
  lower than controls. Nishioka

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But.Costly advice

• Single bed set, 1 pillow, duvet and mattress
  covers 156.00
• Dehumidifier-e.g 299.99
• Air purifier- 359.00
• Vacuum cleaners-upright better but cylindrical
  get to corners!
• TARGET sensitized PATIENT

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PetsPetsPets..stay or go?

• Can we really reduce cat allergen if the cat
  goes, or is it too late?
• Any benefits in buying a cat?

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Pets..can we reduce the allergen load?

• High Efficiency particulate air (HEPA) cleaner
  and cat-induced asthma, 35 cat allergic
  subjects.Wood
• Measures of cat-allergen levels, symptoms ,peak
  flow, medication ,spirometry for 3 months..
• Airborne allergens but not settled-dust
  decreased.
• No change in measured value of disease activity .

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Petsremoval

• Can take more than 20 weeks for cat removal to
  affect allergen content in household-dust
  samples!!.

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Removal of cats

• PEFR improved when high efficiency filter used
  and less bronchodilator needed at 1 year.
• Primarily in those with cat sensitivity without
  their own cat!! Popplewell

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Does clinical tolerance really happen?

• IgG1 and IgG4 were higher in children keeping a
  cat, but not IgE ( same children
  ).Hesselmar.Platts-Mills
• Some children had raised IgG4 but not associated
  with asthma or sensitization and no IgE antibody
  to cats.
• This group had the highest frequency of cat
  keeping.modified Th2 response but no protective
  effect.

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Pet avoidance Secondary Prevention

• EVIDENCE CONVINCING
• Yes or No??
• VOTE

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Early Treatment of the Atopic Child
Study-Southampton 2002Warner

• Children with atopic dermatitis between age1-2
  treated for 18 months with cetirizine( H1
  receptor antagonist) with 18 month follow-up
• Delay or prevention of asthma in subgroup with AD
  sensitized to grass pollen, and less so to HDM.

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Indoor air pollution-Considerations

• Nitrogen oxides from gas cookers.
• Indoor moulds.
• Formaldehyde by some furniture and materials.

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Advice
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Identifying the patient we can help

• Children with asthma and multiple positive skin
  tests or specific IgE have more severe asthma
  than those who are monoallergic .

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Take home messages-For allChildren

• Exclusive breast-feeding and avoidance of
  exposure to environmental tobacco smoke can be
  safely recommended for the whole population.

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Take home messages- For high risk children

• A Protein hydrolysate as a supplement or
  alternative for children who cannot breast feed
  seems to provide further protection.
• In- utero and post natal smoking and paternal
  smoking increases respiratory risks.
• House dust mite allergen avoidance show some
  protection against atopic dermatitis and asthma
  in later childhood.

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Take home messages- For high risk children

• Pets?-further research!!
• Identifying children with sensitization of utmost
  importance in targeting advice, educational
  resources and improving quality of life for
  asthma sufferers.

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• Thank you

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Future treatments

• Immunostimulatory DNA to treat ragweed
  sensitivity.
• Anti-IgE therapy to decrease peanut sensitivity.

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