The effectiveness of house dust mite avoidance and dietary fatty acid modification in asthma prevention

1
?????????????????????????

• The effectiveness of house dust mite avoidance
  and dietary fatty acid modification in asthma
  prevention
• ???????
• ? ????
• ?????????????

2

• ARTICLE 1
• ?? Eighteen-month outcomes of house dust
  mite
• avoidance and dietary fatty
  acid modification in the
• Childhood Asthma Prevention
  Study (CAPS).?? Mihrshahi, S., Peat, J. K.,
  Marks, G. B., Mellis,C. M.,
• Tovey, E. R., Webb, K., Britton,
  W. J., Leeder, S. R. Childhood
• Asthma Prevention Study.
• ?? J Allergy Clin Immunol. 2003
  Jan111(1)162-8.
• ARTICLE 2
• ?? Three-year outcomes of dietary fatty
  acid modification
• and house dust mite reduction in
  the Childhood Asthma
• Prevention Study
• ??Peat, J. K., Mihrshahi, S., Kemp, A. S.,
  Marks, G. B.,
• Tovey, E. R., Webb, K., Mellis,
  C. M., Leeder, S. R.
• ??J Allergy Clin Immunol. 2004 Oct 114(4)
  807-813.

3
Introduction
4
Asthma

• Asthma prevalence
• 87year 16 91year 19
• Risk factor
• Exposure to allergens
• Environmental tobacco smoke
• Respiratory infections in early life
• Dietary factor sodium, antioxidant
• Preventive strategies
• Allergen avoidance
• Avoidance of Environmental tobacco smoke exposure
• Prolongation of breast-feeding
• Beneficial food fish (oil)

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Asthma ?-3 fatty acid

• Epidemiological studies
• National Health and Nutrition Examination survey
  High fish intake,
  ?asthma (Schwartz, J. et al 1990)
• High intake of ?-6 fatty acid, ?asthma risk
  (Haby, M. M. et al. 2001)
• 
  
• Controlled dietary ?-6 fatty acid intake, ??-3
  fatty acid supplement ? biochemical markers
  (Hodge, L. et al. 1998)
• 
  
• A double-blind, randomized trial in children
  24-38mg/kg/d of
  EPA / DHA ? improvement asthma symptoms, ?airway
  responsiveness (Nagakura, T. ea al. 2000)
• 
  
• high marine fatty acid intake may have
  beneficial effects on inflammatory conditions
  such as rheumatoid arthritis, psoriasis, and
  asthma (Kremer, J. M. ea al. 2000 Bittiner, S.
  B. et al. 1988 Black, P. N. et al. 1997)

6
Fatty acid metabolism and eicosanoids

• ? ?-3 fatty acid supplement an
  inhibitory and competitive effect
• ? arachidonic acid-derived
  inflammatory mediators (leukotrienes LT)
• LTC4, D4, E4 slow-reacting
  substance of anaphlaxis
• 
  induces bronchoconstriction, ?vascular
  permeability, mucus secretion
• LTB4
• recruits
  neutrophils, ?vascular permeability, attracts
  inflammatory cells
• modulate airway inflammation

7
Asthma House dust mite allergen

• Epidemiological studies
• In humid region, HDM allergen is a stronger risk
  factor for asthma
  (Sporik, R. et al. 1992)
• New South Wales study in children
• ?HDM allergen, ?current asthma, dose-response
  relation
• 
  (Peat,
  J. K, et al. 1996)
• A randomized trials (n23)
• Chemical and physical methods of HDM allergen
  avoidance ? improvement asthma symptom,
  medication use, peak flow
  (Hammarquist, C. et
  al. 2000)

8
Objective
9

• To measure the effects of dietary
  supplementation
• with ?-3 fatty acid and house dust mite allergen
• avoidance in children with a family history of
  asthma

10
Research Design and Methods
11
Study population

• Childhood Asthma Prevention Study (CAPS)
• A randomized controlled trial
• ParticipantsPregnant women
• unborn children
• high risk of developing asthma
• place 6 hospitals in Sydney, Australia.
• Recruitment time1997.9 1999.12

12
FIG 1. CAPS trial profile
Women assessed for eligibility at 6 antenatal
clinics n7171
Excluded n5076
Met entry criteria n2095
enrollment
Verbally agreed to participate n616
Declined to participate n1479
Reasons for non-participation recorded n1303
randomization
Informed consent obtained at 34-37 weeks pregnant
616 women randomized
Group A N149 Placebo diet supplements No house
dust mite reduction
Group B N155 Placebo diet supplements Active
house dust mite reduction
Group C N159 Active diet supplements No house
dust mite reduction
Group D N153 Active diet supplements Active
house dust mite reduction
13
Inclusion criteria for CAPS

• At least one parent or sibling with symptoms of
  asthma as assessed by screening questionnaire
• Reasonable fluency in English
• Telephone at home
• Reside within 30 km from center of recruitment

14
Exclusion criteria for CAPS

• Pet cat at home
• Families on strict vegetarian diet
• Multiple births
• Babies born earlier than 36 weeks gestation

15
Interventions
Group A Group B Group C Group D
No house dust mite reduction Standard advice. Follow normal washing routines Placebo diet Polyunsaturated Margarines and oil Sunola oil supplements Active house dust mite reduction Standard advice. allergen-impermeable mattress covers, acaricide wash Placebo diet Polyunsaturated Margarines and oil Sunola oil supplements No house dust mite reduction Standard advice. Follow normal washing routines Active diet Canola margarines and oil, Tuna oil supplements Active house dust mite reduction Standard advice. allergen-impermeable mattress covers, acaricide wash Active diet Canola margarines and oil, Tuna oil supplements
16
Dietary intervention
oil Group SFA MUFA PUFA characteristics characteristics
Canola oil Active 8 62 30 Low ?-6 containing monounsaturted oils ?-6 FA 16 ?-9 FA 40 ?-3 FA 6
Soybean-base polyunstaurated oil Placebo 10 28 62 High ?-6 containing polyunsturated oils ?-6 FA 40 ?-9 FA 20 ?-3 FA 1.2
Tuna oil Active 28 24 48 High ?-3 containing polyunsturated oils ?-6 FA 6 ?-3 FA 37
Sunola oil Placebo 7 85 8 Low ?-3 containing monounsaturted oils ?-6 FA 7 ?-3 FA 0.3
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FIG 2. Dietary intervention flow chart
Intervention group
Control group
Families supplied with canola based margarines
and cooking oils
Families supplied with polyunsaturated margarines
and cooking oils
Birth
Birth
Breastfed
Breastfed
Bottlefed
Bottlefed
Tuna fish oil supplements added to formula
Sunola oil supplements added to formula
If formula is introduced before 6 months
If formula is introduced before 6 months
6 months
Sunola oil supplements added to favourite foods
and beverages
6 months Tuna
fish oil supplements added to favourite foods and
beverages
5 years
5 years
18
Table 1. comparison of DHA and EPA content in
infant formula supplemented with Tuna fish oil
and in breast milk
Age (months) Fluid intake (mls) Drops of oil Tuna oil (mg) EPA (mg) formula EPA (mg) breast milk DHA (mg) formula DHA (mg) breast milk
0-1 600 12 300 18 17.4 76.8 51.6
1-3 750 15 375 22.5 21.8 96 64.5
4-6 900 18 450 27 26.1 115.2 77.4
gt6 months 1000 20 500 30 29 128 86
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FIG 3. House dust mite intervention flow chart.
Antenatal home visit (36 weeks gestation)
randomization
Active group playmats, Acaril and covers
provided with special information
Control group standard information provided

Acaril wash
Birth
Normal washing routine
1 month home visit dust collected
Acaril wash
3 month home visit dust collected
Acaril wash
6 month hime visit dust collected
Acaril wash
Washing procedure and dust collection repeated
every 3 months until the child is 5 years old
20
FIG 1. CAPS trial profile
Withdrawn (18month, n62 3 years, n90)
Follow up home visits At 1,3,6,9,12 months and
every 6 months thereafter Symptoms and illness
questionnaire Home
environment questionnaire
Diet questionnaire
Dust collection
Medical assessments At 18 months, 3 years, 5
years Skin prick
tests
Assessment of symptoms and diagnosis
Blood tests
3 day weighed
food record
21
Withdrawal criteria for CAPS (after
randomization)

• Birth weight below 2.5 kg
• Babies requiring surgery
• Babies requiring hospitalization for more than 1
  weeks
• Babies with significant neonatal disease
• Babies with congenital malformations

22
Symptoms and illness questionnaire

• Respiratory history
• Allergic symptoms
• Common childhood illnesses
• Significant medical and surgical problem
• Immunization status
• Growth rates

23
Home environment questionnaire

• Home structural
• Infants sleeps room
• Type of bedding
• Indoor and outdoor temperature and humidity

24
Diet questionnaire

• Breast-feeding
• Infant formula
• Infants first solid foods
• Eating habits
• Compliance with the diet intervention

25
Measuring instruments analysis
Skin prick tests
Five inhalant allergens house dust mite, rye grass, Alternaria, cat, cockroach
Five food allergens milk, egg, peanut, tuna, salmon
Blood tests
Total IgE
Lymphocyte subsets IL-4, IL-5, IL-10, IFN-?
Plasma phospholipids
Dust collection estimate house dust mite allergen exposure levels
26
Assessment of symptoms and diagnosis 18 months

• Atopy ?1 skin prick teats, ?2mm
• symptoms diagnosis wheeze, cough, eczema

27
Assessment of symptoms and diagnosis 3 years
asthma
Trivial asthma ?2 times/18 months wheeze
Infrequent episodic asthma 12 times/ 6 weeks episodes wheeze
Frequent episodic asthma ?3 times/ 6 weeks episodes wheeze
Persistent asthma ?3 times/ 6 weeks episodes wheeze, and daily use of an medication.
cough
Mild cough ? 1 times/week cough, cough during exercise and physical activity.
moderate cough ? 1 times/week cough, cough during exercise and physical activity.
Nonatopic cough Similarly mild or moderate cough without a cold in the last 18 months , No positive skin prick test
Atopic cough Similarly mild or moderate cough without a cold in the last 18 months, ? 1 positive skin prick test.
wheeze
Nonatopic wheeze Wheeze in the last 18 months, No positive skin prick tests
Atopic wheeze Wheeze in the last 18 months, ? 1 positive skin prick test.
Eczemaas either reported eczema or eczema on inspection
Asthma was defined by patterns of wheeze agreed
in the International Consensus Guidelines Adopted
by the National Asthma Council of Australia.
28
Statistical analysis

• ?2 test
• whether the interventions had an
  independent effect on outcome
• Pearson ?2
• was used for 32 tables
• Continuity corrected ?2
• was used for 22 tables
• Logistic regression
• interaction between interventions

29
Results--- 18 months
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Table 2. Demographic data for all groups(1)
Diet intervention Diet intervention Diet intervention House dust mite intervention House dust mite intervention
characteristic placebo N275 placebo N275 active N279 placebo N278 active N276
Mean age (y) SD
Mother 28.98(5.08) 28.98(5.08) 28.51(5.39) 28.67(5.07) 28.82(5.41)
Father 31.16(6.06) 31.16(6.06) 30.75(5.78) 30.51(5.55) 31.43(6.25)
Australian born ()
Mother 71.3 71.3 76.0 77.0 70.3
Father 71.3 71.3 66.3 70.1 67.4
Tertiary educated ()
Mother 46.5 46.5 47.0 45.3 48.2
Father 44.4 44.4 44.1 45.7 42.8
Full-time employment () Full-time employment () Full-time employment ()
Mother Mother 46.2 45.5 46.4 45.3
Father Father 86.2 84.6 86.3 84.4
Asthma () Asthma ()
Mother Mother 54.9 54.5 57.9 51.4
Father Father 40.9 38.4 38.5 40.7
31
Table 2. Demographic data for all groups(2)
Diet intervention Diet intervention Diet intervention House dust mite intervention House dust mite intervention
characteristic placebo N275 placebo N275 active N279 placebo N278 active N276
Hay fever ()
Mother 46.5 46.5 45.5 48.2 43.8
Father 33.6 33.6 28.7 31.3 30.9
Eczema ()
Mother 26.9 26.9 22.6 22.7 26.8
Father 10.6 10.6 13.6 11.9 12.4
Smoking in pregnancy () Smoking in pregnancy () Smoking in pregnancy ()
Mother Mother 23.6 24.0 23.0 24.6
Father Father 16.7 19.0 18.0 17.8
Sex of child () Sex of child ()
Female Female 51.3 49.5 48.6 52.2
Male Male 48.7 50.5 51.4 47.8
Birth weight (kg) SD Birth weight (kg) SD 3.47(0.49) 3.53(0.48) 3.49(0.48) 3.51(0.49)
Birth length (cm) SD Birth length (cm) SD 51.04(2.39) 51.05(2.50) 50.99(2.45) 51.10(2.44)
Head circumference (cm) Head circumference (cm) 34.72(1.50) 34.71(1.46) 34.72(1.54) 34.72(1.42)
Older siblings () Older siblings () 68.4 64.9 66.2 67.0
Ever breast-fed () Ever breast-fed () 68.7 67.4 69.1 67.0
32
Intervention effectiveness

• House dust mite intervention
• Participants beds (mean)
• placebo 15.4µg/g
• Active group 4.6 µg/g ?70 (95
  CI, 64-75)
• Playroom floor (mean)
• placebo 15.11µg/g (95 CI,
  12.27-18.60)
• Active group 10.45 µg/g (95 CI,
  8.39-12.88)
• Diet intervention
• ?-3 plasma fatty acid
• placebo 5.0 (95 CI, 4.8-5.2)
• Active group 6.7 (95CI,
  6.5-7.0 Plt0.0001) ?
• ?-6 plasma fatty acid
• placebo 35.0 (95 CI, 34.6-35.4)
• Active group 32.5 (95CI,
  32.1-32.9 Plt0.0001) ?
• ?-3/?-6
• placebo 17.14
• Active group 15.00 (Plt0.0001)

33

• IgE concentrations
• placebo diet group 22.4 IU/L (95 CI, 15.6-22.7)
• Active diet group 18.8 UL/L (95 CI, 18.1-27.6)
  
• 
  (P.23)
• placebo HDM group 22.4 IU/L (95 CI, 18.6-27.2)
• Active HDM avoidance group 18.6 IU/L (95 CI,
  15.1-23.0)
• 
  (P.19)
• No difference
• Cytokines
• IL-4, IL-5, IFN-? no data
• IL-10 no difference

34
Table 3 . Sensitization to inhaled and ingested
allergens by skin prick testing
at 18 months of age
Diet intervention Diet intervention Diet intervention Diet intervention Diet intervention House dust mite intervention House dust mite intervention House dust mite intervention House dust mite intervention House dust mite intervention
Allergen placebo active difference 95 CI P vaule placebo active Difference 95 CI P vaule
Der p 1 10.1 10.1 0 -5.1-5.0 .99 9.9 10.3 -0.4 -5.5-4.7 .88
Cat 1.1 0 1.1 -0.1-2.4 .07 1.1 0 1.1 -0.1-2.3 .08
Eggs 8.6 6.5 2.1 -2.4-6.5 .36 7.0 8.1 -1.1 -5.5-3.3 .63
Peanuts 4.9 4.3 0.5 -3.0-4.0 .77 5.5 3.7 1.8 -1.7-5.3 .41
Ingested 12.8 11.3 1.5 -4.0-6.9 .69 12.6 11.4 1.2 -4.2-6.7 .69
Inhaled 11.7 11.3 0.4 -5.0-5.7 .89 11.1 11.9 -0.8 -6.3-4.5 .78
Any atopy 21.1 18.2 2.9 -3.9-9.5 .41 19.7 19.6 0.1 -6.5-6.9 .96
The prevalence of sensitization to cockroach,
Alternaria, rye grass, grass mix, cow milk,
salmon, and tuna waslt5 and did not differ
between groups.
35
Table 4. Symptoms of wheeze, cough, and eczema at
18 months of age(1)
Diet intervention Diet intervention Diet intervention Diet intervention Diet intervention
placebo() active () difference 95 CI P value
Wheeze ever 52.6 42.8 9.8 1.5-18.1 .02
Wheeze gt1 wk 29.8 21.9 7.8 0.5-15.1 .04
Wheeze episode gt1 wk without a cold 5.9 7.9 2.0 -6.3-2.2 .34
Wheeze with difficulty breathing 18.0 17.3 0.7 -5.6-7.1 .82
Visit to doctor for wheeze 26.8 20.5 6.3 -0.7-13.4 .09
Visit to emergency for wheeze 12.5 9.7 2.8 -2.5-8.0 .30
Hospital admission for wheeze 6.3 5.0 1.3 -2.6-5.1 .54
Cough gt1 wk without a cold 12.1 13.0 0.9 -4.7-6.4 .76
Eczema or dermatitis 28.1 30.5 2.3 -5.3-9.9 .55
Eczema on inspection 17.4 16.8 0.6 -5.7-6.9 .86
36
Table 4. Symptoms of wheeze, cough, and eczema at
18 months of age(2)
House dust mite intervention House dust mite intervention House dust mite intervention House dust mite intervention House dust mite intervention
placebo() active () difference 95 CI P vaule
Wheeze ever 47.7 47.6 0.1 -8.3-8.3 .99
Wheeze gt1 wk 26.4 25.3 1.1 -6.2-8.4 .77
Wheeze episode gt1 wk without a cold 6.1 7.7 1.6 -2.7-5.8 .47
Wheeze with difficulty breathing 18.1 17.2 0.9 -5.5-7.2 .82
Visit to doctor for wheeze 24.2 23.1 1.1 -6.0-8.2 .76
Visit to emergency for wheeze 10.8 11.4 0.6 -47.-5.7 .85
Hospital admission for wheeze 5.8 5.5 0.3 -3.6-4.1 .86
Cough gt1 wk without a cold 11.6 13.6 2.0 -3.5-7.6 .47
Eczema or dermatitis 25.3 33.5 8.2 0.6-15.8 .04
Eczema on inspection 13.7 20.6 6.9 0.6-13.2 .03
37
Table 5. Medication use at 18 months of age(1)
Diet intervention Diet intervention Diet intervention Diet intervention Diet intervention
placebo() active () difference 95 CI P vaule
Inhaled bronchodilators 47.6 44.1 3.5 -4.8-11.8 .44
Cromoglycate or nedocromil 9.6 6.1 3.5 -1.0-8.0 .13
Inhaled corticosteroids 8.5 7.2 1.3 -3.2-5.8 .57
Oral antihistamines 49.8 48.4 1.4 -6.9-9.8 .74
Nasal steroids 1.5 1.8 0.3 -1.8-2.4 .77
Steroid cream 39.1 37.3 1.8 -6.3-9.9 .66
Emollient creams 36.2 33.0 3.1 -4.8-11.1 .43
Oral prednisone 11.8 10.0 1.8 -3.4-7.0 .51
Albuterol, terbutaline, and/or ipratropium
bromide. Beclomethasone, budesonide, or
fluticasone.
38
Table 5. Medication use at 18 months of age(2)
House dust mite intervention House dust mite intervention House dust mite intervention House dust mite intervention House dust mite intervention
placebo() active () difference 95 CI P vaule
Inhaled bronchodilators 46.4 45.2 1.2 -7.2-9.5 .78
Cromoglycate or nedocromil 7.9 7.7 0.2 -4.3-4.7 .93
Inhaled corticosteroids 7.6 8.1 -0.5 -5.0-4.0 .82
Oral antihistamines 46.4 51.8 5.4 -2.9-13.8 .20
Nasal steroids 1.8 1.5 0.3 -1.8-2.5 .76
Steroid cream 38.1 38.2 0.1 -8.0-8.2 .98
Emollient creams 34.5 34.6 0.1 -8.0-8.0 .99
Oral prednisone 13.7 8.1 5.6 0.5-10.8 .04
Albuterol, terbutaline, and/or ipratropium
bromide. Beclomethasone, budesonide, or
fluticasone.
39
Conclusion and discussion

• 1. Intervention effectiveness achieved the
  expect
• 2. The diet and HDM interventions no difference
• IgE concentrations
• cytokine (IL-10)
• specific sensitization
• 3. The diet interventions
• symptoms ? wheeze prevalence (9.8)
• ?gt1 wheeze prevalence
  (7.8)
• Medication no difference
• Because symptoms of asthma cannot be reliably
  categorized or diagnosed in the period.
• increasing ?-3 fatty acid in the diet
  might have a beneficial effect on wheeze in high
  risk infant.
• 4. The HDM interventions
• symptoms ?reported eczema prevalence
  (8.2)
• ?visible eczema
  prevalence (6.9)
• Medication ?Oral steroid prevalence
• Required to determine these findings

40
Results--- 3 years
41
Table 6. Baseline characteristics of each study
groups
Diet intervention Diet intervention Diet intervention House dust mite intervention House dust mite intervention
Placebo N275 Placebo N275 Active N279 Placebo N278 Active N276
Total number 259 259 267 266 260
Mean age (y)SD
Mother 29.1(5.0) 29.1(5.0) 28.6(5.3) 28.8(5.0) 28.9(5.3)
Father 31.3(6.0) 31.3(6.0) 30.9(5.7) 30.6(5.5) 31.6(6.2)
Australian born ()
Mother 181(69.9) 181(69.9) 202(75.7) 202(75.9) 181(69.9)
Father 182(70.5) 182(70.5) 176(65.9) 185(69.8) 173(66.5)
Tertiary educated ()
Mother 120(46.3) 120(46.3) 128(47.9) 122(45.9) 126(48.5)
Father 113(44.1) 113(44.1) 120(45.3) 122(46.4) 111(43.0)
Asthma () Asthma ()
Mother Mother 144(55.6) 146(54.7) 154(57.9) 136(52.3)
Father Father 107(41.3) 102(38.2) 103(38.7) 106(40.8)
Smoking in pregnancy (Mother) Smoking in pregnancy (Mother) 58(22.4) 62(23.2) 60(22.6) 60(23.1)
Sex of child (male) Sex of child (male) 127(49.9) 134(50.2) 136(51.1) 125(48.1)
Older siblings Older siblings 178(68.7) 172(64.4) 177(66.5) 173(66.5)
Breast-fed at 1 mo Breast-fed at 1 mo 181(69.9) 181(67.8) 187(70.3) 175(67.3)
42
Intervention effectiveness

• House dust mite intervention
• childs bed (mean)
• Placebo 16.6µg/g (95 CI,
  14.8-18.1)
• Active group 5.5 µg/g (95 CI,
  4.9-6.2) ?3 fold
• Diet intervention
• ?-3 plasma fatty acid
• Placebo 4.9 (95 CI, 4.7-5.1)
• Active group 6.3 (95CI,
  6.1-6.6 Plt0.0001) ?
• ?-6 plasma fatty acid
• Placebo 35.7 (95 CI, 35.3-36.0)
• Active group 33.3 (95CI,
  32.9-33.7 Plt0.0001) ?
• ?-3/?-6
• Placebo 17.7
• Active group 15.6 (Plt0.0001)

43

• IgE concentrations (Mean)
• Placebo diet group 40.1 kIU/L (95 CI,
  32.5-49.5)
• Active diet group 31.0 kUL/L (95 CI,
  25.0-38.4)
• 
  (P.09)
• Placebo HDM group 38.3 kIU/L (95 CI, 31.1-47.2)
• Active HDM avoidance group 32.3 kIU/L (95 CI,
  26.0-40.1)
• 
  (P.26)
• No difference

44
Table 7. Prevalence of respiratory and allergic
outcomes by dietary intervention group
Diet intervention Diet intervention Diet intervention Diet intervention Diet intervention
outcomes Total number placebo active difference P value
No asthma 311 151(58.3) 160(59.9) -1.6 .99
Trivial asthma 90 45(17.4) 45(16.9) 0.5
Infrequent episodic asthma 93 47(18.1) 46(17.2) 0.9
Frequent episodic asthma 20 10(3.9) 10(3.7) 0.2
Persistent asthma 12 6(2.3) 6(2.2) 0.1
No cough 237 102(39.4) 135(50.6) -11.2 .03
Mild cough 239 127(49.0) 112(41.9) 7.1
moderate cough 50 30(11.6) 20(7.5) 4.1
No wheeze 311 151(58.3) 160(59.9) -1.6 .93
Nonatopic wheeze 141 71(27.4) 70(26.2) 1.2
Atopic wheeze 74 37(14.3) 37(13.9) 0.4
No cought 237 102(39.4) 135(50.6) -11.2 .003
Nonatopic cough 200 100(38.6) 100(37.5) 1.1
Atopic cough 89 57(22.0) 32(12.0) 10.0
No eczema 371 178(68.7) 193(72.3) -3.6 .49
Nonatopic eczema 91 50(19.3) 41(15.4) 3.9
Atopic eczema 64 31(12.0) 33(12.4) -0.4
Atopy to ingested allergens 45 24(9.4) 21(8.0) 1.6 .69
Atopic to inhaled allergens 138 76(29.7) 62(23.7) 6.0 .15
House dust mite atopy 114 63(24.6) 51(19.5) 2.1 .16
45
Table 8. Prevalence of respiratory and allergic
outcomes by house dust mite intervention group
House dust mite intervention House dust mite intervention House dust mite intervention House dust mite intervention House dust mite intervention
outcomes Total number placebo active difference P value
No asthma 311 152(57.1) 159(61.2) -4.1 .66
Trivial asthma 90 46(17.3) 44(16.9) 0.4
Infrequent episodic asthma 93 48(18.0) 45(17.3) 0.7
Frequent episodic asthma 20 12(4.5) 8(3.1) 1.4
Persistent asthma 12 8(3.0) 4(1.5) 1.5
No cough 237 113(42.5) 124(47.7) -5.2 .18
Mild cough 239 122(45.9) 117(45.0) 0.9
moderate cough 50 31(11.7) 19(7.3) 4.4
No wheeze 311 152(57.1) 159(61.2) -4.1 .36
Nonatopic wheeze 141 71(26.7) 70(26.9) -0.2
Atopic wheeze 74 43(16.2) 31(11.9) 4.3
No cought 237 113(42.5) 124(47.7) -5.2 .22
Nonatopic cough 200 101(38.0) 99(38.1) -0.1
Atopic cough 89 52(19.5) 37(14.2) 5.3
No eczema 371 199(74.8) 172(66.2) 8.6 .06
Nonatopic eczema 91 42(15.8) 49(18.8) -3.0
Atopic eczema 64 25(9.4) 39(15.0) -5.6
Atopy to ingested allergens 45 19(7.3) 26(10.2) 2.9 .31
Atopic to inhaled allergens 138 80(30.5) 58(22.7) 7.8 .05
House dust mite atopy 114 68(25.6) 48(18.4) 7.2 .05
46
Conclusion and discussion

• 1. Intervention effectiveness achieved the
  expect
• 2. The diet and HDM interventions no difference
• IgE concentrations
• asthma and wheeze prevalence
• 3. The diet interventions
• ?mild cough prevalence (7.1)
• ?moderate cough prevalence (4.1)
• ?atopic cough prevalence (10.0)
• cough in children has sometimes been regarded
  as synonymous with asthma.
• A possible mechanism for the protective
  effect of ?-3 fatty acid supplementation is a
  reduction in arachidonic acid-derived
  inflammatory mediators, such as leukotrienes
  (LT).
• 4. The HDM interventions
• ?atopy to inhaled allergens prevalence
  (7.8)
• ?HDM atopy prevalence (7.2)
• 5. No significant interaction between
  interventions was observed.
• 6. Potential confounders were equally distributed
  among the group.

47
summary

• 1. The results of those study suggest that
  increasing ?-3 fatty acid in the diet might have
  a beneficial effect on asthma prevention.
• 2. Primary preventive interventions may have
  significant long-term rather than early effect.

48
Reference

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49
Thanks for your attention