Letters

Control of house dust mite in managing asthma

BMJ 1999; 318 doi: https://doi.org/10.1136/bmj.318.7187.870 (Published 27 March 1999) Cite this as: BMJ 1999;318:870

Effectiveness of measures depends on stage of asthma

  1. Sonja G M Cloosterman, Epidemiologist (S.Cloosterman@hsv.kun.nl),
  2. Onno C P van Schayck, Professor of preventive medicine
  1. Department of General Practice and Social Medicine, 229 University of Nijmegen, PO Box 9101, 6500 HB Nijmegen, Netherlands Competing interests: None declared
  2. Greater Glasgow Health Board, Dalian House, PO Box 15327, Glasgow G3 8YU
  3. Asthma and Allergic Diseases Center, University of Virginia, Box 225 Health Sciences Center, Charlottesville, VA 22908, USA
  4. School of Health, University of Teesside, Middlesbrough TS1 3BA
  5. Nordic Cochrane Centre, Rigshospitalet, Department 7112, DK-2200 Copenhagen N, Denmark
  6. Executive Office, Unit of Public Health, Municipality of Gotland, S-62181, Visby, Sweden
  7. Centre for Applied Public Health Medicine, University of Wales College of Medicine, Cardiff CF1 3NW

    EDITOR—In their meta-analysis G⊘tzsche et al concluded that measures to control house dust mites are not clinically effective in patients with asthma who are sensitive to mites.1 In the accompanying editorial Strachan commented that this was probably because several control measures used in the included studies did not result in a (relevant) reduction in concentrations of house dust mite allergens. Improvements in clinical condition are consequently not to be expected. Some studies in the meta-analysis found clinical effects while others did not.1 This may not be a result of effectively reducing allergen concentrations but of measuring different groups of asthmatic patients in different stages of disease. We believe that early treatment of mild asthma might have more impact than treating mild to moderate asthma.

    Morning peak flow rates in subjects with allergy to house dust mites and early signs of asthma or confirmed mild asthma during placebo and active strategies to avoid allergens*P<0.05

    We investigated the (clinical) effects of a combined allergen avoidance strategy (use of covers on mattresses and bedding that are impenetrable to house dust mites and use of benzyl benzoate (Acarosan) on living room and bedroom floors) in two groups of subjects allergic to house dust mites. One group had some early signs of asthma2 but no diagnosis and the other had a confirmed diagnosis of mild asthma.3 In the subjects without diagnosed asthma, peak flow rates and symptom scores stabilised during follow up (figure (top)), suggesting that the onset of asthma may have been delayed. The subjects with mild asthma showed no clinical effects during the same follow up (figure (bottom)), although allergen concentrations were reduced, especially on mattresses (10-fold, P=0.0001).3

    We hypothesise that allergen avoidance has more impact as an early preventive measure than as treatment of mild asthma. In …

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