Download Pdf: Clinical Special – Allergy Prevention
Definitions
- Primary Prevention: Preventing immunological sensitisation (i.e. the development of IgE antibodies).
- Secondary Prevention: Preventing the development of an allergic disease following sensitisation and especially development of atopic eczema/atopic dermatitis, upper respiratory allergy, and allergic asthma.
- Tertiary Prevention: Treating asthma and allergic diseases.
- Allergy: Hypersensitivity reaction initiated by immunological mechanisms.
- Atopy: Personal and/or familial tendency to become sensitised (usually in childhood or adolescence) and produce IgE antibodies in response to ordinary exposure to low doses of allergens, usually proteins. As a consequence, atopic individuals can develop typical symptoms of allergic asthma, allergic rhinitis and allergic conjunctivitis, or atopic eczema/atopic dermatitis.
Summary of Evidence-Based Guidelines
Primary prevention
- Avoid smoking / exposure to tobacco smoke, particularly during pregnancy and early childhood (B).
- Avoid damp housing conditions (C), and reduce indoor air pollutants (C).
- Breast-feed exclusively until 6 months (B)*. No special diet for the lactating mother (A).
- Eliminate sensitising and highly irritating agents in occupational environments (C). If this is not possible, implement measures to prevent employee exposure.
* Studies suggest that exclusively breast-feeding and avoidance of solid foods for at least 4 months seems to be effective for allergy prevention.
Secondary prevention
- Treat atopic eczema/atopic dermatitis topically, and possibly with systemic pharmacotherapy, to prevent respiratory allergy (D).
- Treat upper airways disease (e.g. allergic rhinitis) to reduce the risk of development of asthma (D).
- In young children already sensitised to house dust mites, pets or cockroaches, specific exposure should be reduced or abolished to prevent onset of allergic disease (B).
- Remove exposure of employees who have developed symptoms caused by occupational allergic sensitisation (C).
Tertiary prevention
- Infants with cow’s milk allergy should avoid cow’s milk proteins; if a supplement is needed, consider the use of hypoallergenic formula (B).
- Patients with allergic asthma, allergic rhinitis and allergic conjunctivitis, or atopic eczema/atopic dermatitis who are allergic to indoor allergens such as dust mites, cockroaches and animal danders should eliminate or markedly reduce the exposure to improve symptom control and prevent exacerbations. Bed covers are particularly useful for allergic patients sensitised to mites (A.B) (see box).
- Aim pharmacotherapy primarily towards the underlying inflammatory process (A).
- Avoid strictly acetyl salicylic acid or other non-steroidal anti-inflammatory drugs (NSAIDs) in patients who are sensitive to them after an appropriate diagnosis has been confirmed (C).
Education
- Patient education regarding precipitants of asthma, allergic symptoms, and especially anaphylaxis is essential. Guided self-management to prevent, assess and treat symptoms is the key to optimising disease control (A).
| House dust mite allergen reduction:
Aims to reduce exposure to mite allergens in the home Wash regularly bedding (every 1 – 2 weeks), pillows and duvets at 55-60oC, if possible, to kill mites Sufficient ventilation of dwellings to decrease indoor humidity below 50% Remove/reduce curtains, carpets, soft toys from the bedroom Exposure of mattresses, rugs and carpets to direct strong sunlight (for more than 3 hours) kills mites |
| Pollen avoidance:
Provides mechanical barriers to pollen contact · Keep windows closed at peak pollen times, eg, in the evening when airborne pollens descend to lower altitudes · Wear glasses or sunglasses to prevent pollens entering the eyes · Consider wearing a mask over nose and mouth to prevent inhalation of pollens at peak time · Do not cut grass yourself, and keep windows closed when the grass has been mown · Use air-conditioning if possible · Install car pollen filters if possible |
A: Evidence from randomised controlled trials
B: Evidence from controlled study without randomisation or other type of quasi-experimental study, or extrapolated from A.
C: Evidence from non-experimental descriptive studies (e.g. comparative/correlation studies), or extrapolated from B.
D: Expert opinion, or extrapolated from C.
Reference: World Health Organization. Prevention of Allergy and Allergic Asthma. Based on the WHO/WAO Meeting on the Prevention of Allergy and Allergic Asthma, Geneva, 2002.