Page 1

Allergen avoidance in house dust mite allergy

Speaker: Susanne Lau

29 September 2012


Allergen avoidance in house dust mite allergy The 9th Symposium on Specific Allergy 2012 Susanne Lau, CharitĂŠ Berlin


Disclosures • Lecture fees: GSK, Asche Chiesi, Novartis, SymbioPharm • Industry-sponsored grant (institution): SymbioPharm

• Consultancy: Merck


Primary prevention


The childhood asthma prevention study (CAPS) • Study design: Randomized, controlled interventional trial including 516 families from Sydney (Marks, Tovey). • Intervention: mite allergen reduction (B), dietetic supplementation of Omega-3-fatty acids for 6 months (C), or a combination(D), placebo (A) • Outcome: Atopic sensitization and asthma at age 1 and 5 years


CAPS Study Australia • No significant effect!! • Still high exposure in the avoidance group.


Prevention and Incidence of Asthma and Mite Allergy (PIAMA) • Dutch cohort study, inclusion of 1282 families, intervention double-blind, placebo-controlled (encasings vs. placebocovers vs. no intervention from last trimenon of pregnancy)

• Results at first birthday: only significant difference for nocturnal cough in the encasing group (OR 0.68; 0.4-1.0) Koopmann Am J Respir Crit Care Med 2002


MAAS (Manchester Asthma and Allergy Study) • Prospective cohort study including 291 infants at risk, no pets. • Intervention: mite allergen reduction • Results at 1. birthday: less wheezy bronchitis in the intervention group (OR 0.44; 0.2-1.0). • 3. birthday: higher risk for sensitization in the intervention group (mite sensitisation RR 2.85) but less asthma and lower sRAW (p<0.003).

Custovic Lancet 2001, Woodcock AJRCCM 2004


Sensitization at age 3 (%) * p<0.05

Lowe Am J Respir Crit Care Med 2004


The Canadian Asthma Primary Prevention Study • 545 newborns at risk (family history for asthma) • Randomized placebo-controlled intervention • Intervention: Encasings, weekly washing of bedding, benzyl benzoate on carpets and upholstery before birth and 4 and 8 weeks after birth. • No pets, no ETS, no daycare during the first 12 months of life.


Symptoms at age 2 and 7 years %

Control group

Intervention group

aOR (95%)

Wheeze 7 y

29

17

0.42

P value .001

(0.25-0.71)

Eczema 7 y

13.5

12.4

0.92

.791

(0.49-1.73)

Wheeze 1 y

20

15

0.68

n.s.

(0.42-1.09)

Wheeze 2 y

23

16

0.6 (0.37-0.95)

Main exposure: ETS

Becker JACI 2004

.05


Multifaceted approach in the Isle of Wight Study • 120 high risk babies • single blinded, controlled trial • breast feeding, low allergen diet in lactating mothers for 12 months or hydrolyzed formula • house dust mite allergen avoidance measures: vinyl covers for mattresses, acaricides. HDM allergen levels 5.9 microgram/gram versus 15 µg/g of mattress dust (intervention versus control at day 0 and after 9 months). • Follow-up until 18 years of age. Scott Thorax 2012


Isle of Wight Study

Arshad JACI 2007


Isle of Wight Study

No effect on sensitization at age 18

Scott Thorax 2012


Secondary prevention


Early sensitisation and allergen exposure to perennial allergens * and lung function at school age

160

not sensitised

sensitised / low exposure

p = 0.003

140

p = 0.018 p < 0.001

120

Mean + /â&#x20AC;&#x201C; SD

sensitised / high exposure

p = 0.001

p = 0.020

p = 0.003

p = 0.025

100 80 60 40 20 0 FEV1 (% FVC)

MAS-90

Illi Lancet 2006

FEV1 (% pred)

MEF75 (% pred)

MEF50 (% pred)

MEF25 (% pred)

* Sensitisation / exposure to mites and/or cats up to the age of 3 years


House dust mite allergen reduction in children with mite-allergy and asthma

*

*

*

Ehnert et al JACI 1992; 90: 135ff


BHR in children with mite allergy and asthma

*

*

Ehnert et al JACI 1992; 90: 135ff


GØtzsche et al Allergy 2008; 63:646 • Systemic review • 54 studies (3002 patients) • 26 studies on mattress encasings • 10 studies using chemicals • Criticism: mixed study populations, often polysensitized • No control of success of the intervention (allergen reduction)


HDM avoidance and self-management in allergic asthmatic patients • prospective, randomised placebocontrolled trial, follow-up 2 years • 126 mite-sensitised asthmatic patients • age 16-60 years, ICS required • results: after 1 and 2 years no significant differences in mite allergen exposure between control group and group using mite impermeable covers de Vries Br J Gen Pract 2007


Primary outcome â&#x20AC;˘ step down: ICS dose reduction (half budesonide dosage) if peak flow improves to >= 80% of personal best value â&#x20AC;˘ step up: double budesonide dosage if peak flow deteriotes < 80% PEFR >= 60% of PBV for 2 out of 3 consecutive days de Vries Br J Gen Pract 2007


ICS in asthmatics during intervention

de Vries Br J Gen Pract 2007


Airsonett „Protexo“ • Temperature-controlled laminar airflow for the reduction of nocturnal allergen exposure


Body convection and allergen exposure The higher temperature (+2 째C) of the head and convection cause a vertical airflow of 0.2 m/s. Allergens transported in the airflow can be inhaled.

Ref: 6. Mundt E. Performance of displacement ventilation systems 1996.


Temperature controlled Laminar Airflow (TLA) TLA achieves a significant allergen and particle reduction, measured in patients` breathing zone.8,9 Gradient of 0.5 째 C

Ref: 8. Data on file. Report - particle measurements in breathing zone, at Airsonett AB. 9. Data on file. Elfman L. Pegasus lab. Report - allergen measurements in breathing zone, at Airsonett AB


Comparison air cleaner and TLA

Part/ft3 1,000’

TLA

100’

Air cleaner 10’

5’

Air cleaner Clean Room level

5,000 part/ft3

TLA treatment 30 min

1 2

3

4

5

6

7

8

9

10 Hours

Ref 1: Custovic A, Simpson A, Chapman MD,Woodcock, A. Allergen avoidance in the treatment of asthma and atopic disorders. Thorax 1998;53:6372. 2: Gøtzsche PC, Johansen HK. House dust mite control measures for asthma. Cochrane Database of Systematic Reviews 2008, Issue 2. Art. No.: CD001187. DOI: 10.1002/14651858.CD001187.pub3


TLA study (Protexo) • Randomized, controlled trial including 312 patients with controlled persistent asthma (aged 7-70 years) and mite and/or pet allergy. Drop out 30 patients. (n=282) • One year of treatment • Outcome: AQoL

Boyle Thorax 2011


Boyle Thorax 2011


Summary house dust mite avoidance • Primary prevention: • No effect on mite sensitization. Minor decrease of BHR (cough, wheeze). • Secondary prevention: • In younger children with monosensitization reduction of BHR. • Often helpful in addition with immunotherapy and pharmacotherapy.

Susanne Lau  
Read more
Read more
Similar to
Popular now
Just for you