Effects of house dust mite avoidance measures on Der p 1 concentrations and clinical condition of mild adult house dust mite-allergic asthmatic patients, using no inhaled steroids.
BACKGROUND
Exposure to house dust mite (HDM) allergens often results in worsening of asthma. Therefore, avoidance of exposure to HDM allergens is often proposed. Unfortunately, the most effective and feasible avoidance strategy is still not completely assessed. Consequently, we investigated the effects of a combined HDM avoidance strategy on HDM allergen concentrations and clinical condition of allergic, mild asthmatic, patients using no inhaled steroids.


METHODS
Asthmatic patients, allergic to HDM, using no inhaled corticosteroids, were randomly allocated to an active (n = 76) or a placebo allergen-avoidance group (n = 81). Avoidance measures consisted of applying Acarosan(R) (placebo: water) to the living room and bedroom floors, and the use of HDM-impermeable covers for mattresses and bedding (placebo: cotton covers for mattresses only). Effects on allergen concentrations (Der p 1), FEV1, bronchial hyperresponsiveness, peak flow parameters and asthma symptom scores were studied during 20 weeks and controlled for the allergic status of the patients.


RESULTS
The active covers reduced Der p 1 concentrations to 9.4% (P = 0.0001), and were always significant lower than in the placebo group (P = 0.0002). Acarosan(R) resulted in slight but significant decreases (twofold, P = 0.0001), both on living room and bedroom floors, but concentrations were never significantly lower than the placebo group. Although the combined avoidance strategy resulted in a considerable reduction in allergen load in the active group, no differences were seen between the two groups in any of the clinical parameters during the follow-up period in this group of allergic asthmatics, using no inhaled corticosteroids. Corrections for the allergic status did not alter these results.


CONCLUSIONS
The combined avoidance strategy was effective in reducing HDM allergen concentration. This was especially achieved by the allergen-impermeable covers, while the effects of Acarosan(R) were only marginal. However, this allergen reduction was not reflected in a convincing improvement in clinical condition in this group of mild allergic asthmatics, using no inhaled steroids. Perhaps, a longer follow-up period would have resulted in more pronounced effects.
Cloosterman
S G
SG
Department General Practice and Social Medicine, University of Nijmegen, Nijmegen, The Netherlands.
Schermer
T R
TR
Bijl-Hofland
I D
ID
Van Der Heide
S
S
Brunekreef
B
B
Van Den Elshout
F J
FJ
Van Herwaarden
C L
CL
Van Schayck
C P
CP
D000280:Administration, Inhalation; D000293:Adolescent; D000328:Adult; D016902:Air Pollution, Indoor / Q000009:adverse effects / Q000517:prevention & control; D000485:Allergens / Q000009:adverse effects* / Q000276:immunology; D000818:Animals; D039741:Antigens, Dermatophagoides; D001249:Asthma / Q000276:immunology / Q000517:prevention & control*; D001565:Benzoates / Q000494:pharmacology; D004391:Dust / Q000009:adverse effects / Q000517:prevention & control*; D005260:Female; D006023:Glycoproteins / Q000009:adverse effects* / Q000276:immunology; D006801:Humans; D007306:Insecticides / Q000494:pharmacology; D008297:Male; D008875:Middle Aged; D008925:Mites / Q000187:drug effects / Q000276:immunology*; D010366:Peak Expiratory Flow Rate; D011241:Prednisone / Q000008:administration & dosage*; D012129:Respiratory Function Tests
D000485:Allergens; D039741:Antigens, Dermatophagoides; D001565:Benzoates; D004391:Dust; D006023:Glycoproteins; D007306:Insecticides; C006723:benzyl benzoate; D011241:Prednisone