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Practical Issues in Asthma Prevention Dr Marie Wheeler General Paediatrician Cheltenham General Hospital/Gloucestershire Hospitals NHS Trust
Outline of discussion n Asthma and its prevalence n Primary and secondary prevention (Diet, House Dust Mites, pets, smoking) n Targeting all this advice. ? ? n Take home messages !!
Asthma in Children… Accurate diagnosis…challenge in children. n Education, Education. n Asthma guidelines-British Thoracic Society/SIGN 2005. n Compliance and more education. n Advice re. primary and secondary prevention. n
Asthma and Allergy n 1/3 of 4 year olds with persistent wheeze are sensitive to at least one common aeroallergen. n In older children asthma closely associated with allergy with approx. 2/3 affected.
n. British ‘’New cases of Medical Journal March 2005…. asthma in children fall by two thirds. The number of new cases of asthma fell significantly in England Wales between 1996 and 2003, with the number in children falling the most, the latest issue of Social Trends says. ’ ‘’New episodes halved among the 5 to 24 years age group. The issue does not indicate any possible reasons for this. ’’
International Study of Asthma and Allergies in childhood(ISAAC)Burr n 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
Primary Prevention § Breast feeding § Smoking § Allergen avoidance-HDM, Pets.
Primary Prevention. Breastfeeding. n n n 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)
Other milks n Protein hydrolysate as a supplement or alternative for children who cannot breast feed seems to provide protection.
Primary Prevention-Smoking n Pregnancy smoking affects infants airway function with increased airway resistance at 4 weeks Young. n Increased risk of wheeze is associated with smoking in pregnancy and maternal postnatal smoking.
Smoking n . In- utero exposure seems to have more impact on childhood lung function. Gilliland than post natal smoking.
Smoking n Consistent odds ratio for respiratory illness 1. 2 to 1. 6 for either parent smoking. Cook. Odds higher for preschool than school age. n Significant effects from paternal smoking too. n
Smoking n 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
Primary Prevention-Allergen Exposure n Early exposure to allergens causes sensitization but development of asthma not demonstrated Lau. n Considerations given to HDM prevention measures, diet, omega-3 fatty acids, probiotics, H 1 antagonists, immunotherapy, ketotifen.
House Dust Mite- (700, 000 hits on google) n Dermatophagoides pteronyssinus
David Hide Asthma and Atopy Research Centre-Isle of Wight 2003 n n n 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
Study of Prevention of Allergy in Children in Europe 2004 Horak >600 high risk newborns. n One group- mite-impermeable mattress encasing and simple educational package on allergen avoidance. Control given basic allergy information. n At age 2 no difference in HDM sensitization, nocturnal cough, wheezing. n
Childhood Asthma Prevention Study-Australia 2004 Peat >600 High Risk Children enrolled (antenatally) n Given omega-3 fatty acids and HDM preventative measures. n At age 3 significant reduction in cough and HDM sensitization but not wheeze. n
House Dust Mite Primary Prevention EVIDENCE CONVINCING? n Yes or No? ? n VOTE
Pets Stay or go? n Should we have pets before we have children? n
Pets. . to stay…to buy… n 400 + children in Sweden Hesselmar 1999 n Children exposed to pets during the first year of life had less allergic rhinitis at age 7 -9 and less asthma at age 12 -13. n (Increasing no. of siblings associated with less too. )
Pets…. to go n Prenatal manipulation in high risk for atopy, couples reduced some respiratory symptoms in the first year of life. n Cat ownership was significantly associated with sensitization to cats (Custovic A et al, Manchester 2001)
Pet avoidance Primary Prevention EVIDENCE CONVINCING n Yes or No? ? n VOTE
Secondary Prevention § House dust mites-Cochrane reviews. . ’may’! n Pets § Smoking
House dust mites Likes; Warmth Moisture Shedded human skin Carpets Soft furnishings Curtains
House dust mites Dislikes; Ventilation-dehumidifiers Damp dusting HEPA filters Freezers-Soft toys. Barrier covers High temp(>50 degree c) A mite-killing material in a low-temp. wash Acaricidal powder
House Dust Mites-Summary n Restricting exposure significantly reduces asthma signs and symptoms ( less days of wheeze, reduced requirement for medication, fewer abnormal peak flows) in some studies. n Highly significant reduction in Ig. E in some studies.
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 Ig. E to HDM was lower than controls. Nishioka
But…. Costly advice n Single bed set, 1 pillow, duvet and mattress covers £ 156. 00 n Dehumidifier-e. g £ 299. 99 n Air purifier- £ 359. 00 n Vacuum cleaners-upright better but cylindrical get to corners! n TARGET sensitized PATIENT
Pets; Pets. . stay or go? Can we really reduce cat allergen if the cat goes, or is it too late? n Any benefits in buying a cat? n
Pets. . can we reduce the allergen load? n High –Efficiency particulate air (HEPA) cleaner and catinduced asthma, 35 cat allergic subjects. Wood n Measures of cat-allergen levels, symptoms , peak flow, medication , spirometry for 3 months. . n Airborne allergens but not settled-dust decreased. No change in measured value of disease activity. n
Pets…removal n Can take more than 20 weeks for cat removal to affect allergen content in household-dust samples!!.
Removal of cats PEFR improved when high efficiency filter used and less bronchodilator needed at 1 year. n Primarily in those with cat sensitivity without their own cat!! Popplewell n
Does clinical tolerance really happen? n Ig. G 1 and Ig. G 4 were higher in children keeping a cat, but not Ig. E ( same children ). Hesselmar. Platts-Mills n Some children had raised Ig. G 4 but not associated with asthma or sensitization and no Ig. E antibody to cats. This group had the highest frequency of cat keeping…. modified Th 2 response but no protective effect. n
Pet avoidance Secondary Prevention EVIDENCE CONVINCING n Yes or No? ? n VOTE
Early Treatment of the Atopic Child Study-Southampton 2002 Warner Children with atopic dermatitis between age 1 -2 treated for 18 months with cetirizine( H 1 receptor antagonist) with 18 month follow-up n Delay or prevention of asthma in subgroup with AD sensitized to grass pollen, and less so to HDM. n
Indoor air pollution-Considerations Nitrogen oxides from gas cookers. n Indoor moulds. n Formaldehyde by some furniture and materials. n
Identifying the patient we can help… n Children with asthma and multiple positive skin tests or specific Ig. E have more severe asthma than those who are monoallergic.
Take home messages-For all Children n Exclusive breast-feeding and avoidance of exposure to environmental tobacco smoke can be safely recommended for the whole population.
Take home messages- For high risk children n 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.
Take home messages- For high risk children § Pets? -further research!! n Identifying children with sensitization of utmost importance in targeting advice, educational resources and improving quality of life for asthma sufferers.
Future treatments Immunostimulatory DNA to treat ragweed sensitivity. n Anti-Ig. E therapy to decrease peanut sensitivity. n