Summary points, and will the new evidence change our clinical practice?
Professor Hywel Williams, Clinical Lead for NHS Evidence - skin disorders and Co-ordinating Editor of the Cochrane Skin Group, and Dr Kave Shams, Dermatology Registrar, Southern General Hospital, Glasgow
Food allergy: The US National Institute of Allergy and Infectious Diseases has produced extensive, high quality draft guidelines on the management of food allergy. The advice on food allergy is still limited by lack of clear definitions and a poor evidence base. The guidelines emphasise the importance of taking a good clinical history of food allergy before proceeding to skin-prick or RAST tests, and of the need to be aware of non-IgE mediated food allergy.
Action: We will continue to ask all our eczema patients (especially younger children) about symptoms suggestive of immediate and delayed food allergy to foods such as egg, milk, fish, citrus and nuts. We will not blindly order "allergy tests" on patients, as positive tests have a low predictive value.
CAUSES OF ECZEMA
Risk of cancer: Some evidence points to a possible reduced risk of glioma and acute leukaemia in people who have had eczema in childhood, the reasons for which are unclear.
Action: Given that most of our messages are doom and gloom, this observation of a possible health benefit of having eczema is perhaps worth mentioning to some parents who feel despondent about eczema.
Risk of multiple sclerosis: There is no clear evidence to support an increased or decreased risk of multiple sclerosis in eczema and other atopic diseases.
Action: None, especially as we were not aware of the possibility of an association in the first place.
Attention deficit hyperactivity disorder (ADHD): Although some cross sectional studies suggest a possible association between reported eczema and ADHD, we are not convinced it is a true association at this stage and large prospective studies are needed to disentangle cause and effect.
Action: We shall be cautious accepting that children who are restless because of undertreated eczema have ADHD. We shall treat the underlying eczema aggressively and see how the behaviour improves.
Living in the city: Most studies in developed countries looking at whether eczema is commoner in urban as opposed to rural locations suggest an increased risk of disease expression in urban areas.
Action: The evidence is not strong enough to recommend our patients to move to “a place in the country”.
Hydrolyzed milk formulas: Although a recent systematic review sponsored by the manufacturers of hydrolyzed milk formulas has suggested that partially hydrolyzed formulas from birth may prevent eczema to some degree, compared with standard cow’s milk formula, we would like to see an independent Cochrane Review update on this topic.
Action: We will continue to advise parents that breast-feeding is the most effective and appropriate method to nourish infants, and that mothers who cannot breastfeed can use conventional formula milk. If their child does develop cow’s milk allergy, then a hydrolyzed milk formula is appropriate.
Organic foods: There is no robust evidence that consumption of organic foods reduces the risk of eczema. One cohort study from the Netherlands has suggested that consumption of strictly organic dairy products may reduce eczema risk in infants, a finding that needs to be tested in new studies.
Action: We will not be recommending organic foods during infancy if parents do not choose to buy them.
Fish oils for pregnant mothers: Observational and intervention studies evaluating increased fish intake or fish supplementation during pregnancy suggest a possible reduction in subsequent eczema prevalence and severity.
Action: Although the evidence is not strong enough yet to inform guidelines, the possibility of increasing fish intake or of fish oil supplementation during pregnancy may be something to discuss with families with allergic disease, given the safety and other health benefits of fish oils.
Fish oils for infants: The evidence to support increased fish intake or fish oil supplementation in infant diets to prevent or reduce the severity of subsequent eczema is not so strong.
Action: Hold off the extra fish fingers for now.
Food allergy: A very large, well conducted systematic review on food allergy has highlighted the confusion around the topic. The review calls for clearer definitions of food allergy, and for standardisation in testing methods and quantification.
Action: We shall continue to consider the possibility of food allergy in those with eczema, especially in infants, but we remain unclear about the best method of diagnosing such food allergy.
Bath emollients: Although few would question the value of emollients in the dry skin associated with eczema, the evidence showing any additional value of bath emollients is questionable because they may never achieve an adequate emollient concentration, much ends up down the drain rather than on the skin, and their use may divert attention away from direct application of emollients in the belief that the bath emollient has done the job.
Action: Whilst we would not actively stop a child from using bath emollients if they like them, we recommend more attention is paid to direct application of emollients after bathing rather than what is put in the bath.
Topical tacrolimus and pimecrolimus: Some comparative efficacy evidence shows that both 0.03% and 0.1% tacrolimus ointment is more effective than 1% pimecrolimus, with a similar range of short-term adverse events.
Action: It is still unclear whether 0.03% tacrolimus is any better than pimecrolimus. We will continue to use either for children with eczema within their licensed indications, and swap from one to the other if the child fails to notice any benefit or reports troublesome burning which lasts more than a week.
Silk clothing: Two small studies have evaluated specialised silk clothing for children with eczema. No clear positive findings were shown and both studies had significant flaws.
Action: We do not recommend that parents are advised to purchase silk clothing for children with eczema and we really need some better studies addressing this issue. If children with eczema try silk clothing and like it, then it is up to families whether they buy it.
Bandages: The evidence base for occlusive therapy with dry or wet-wrap bandages with or without emollients or topical corticosteroids is increasing, but the studies still differ too much in terms of who is studied, and how the occlusive therapy is used, to make any strong recommendations, especially with regards to dry bandages. Wet-wraps as an adjunctive treatment for refractory eczema appear to be useful, but concerns about skin infection and the clinical significance of enhanced absorption of topical corticosteroids require bigger and better studies.
Action: We will continue to use wet-wrap bandages over topical corticosteroids for short periods of up to one week for acute flares of uninfected and heavily excoriated limb eczema that does not respond to conventional topical corticosteroids and emollients.
Antistaphylococcal interventions including bleach baths: There is still no clear evidence that anti-staphylococcal treatments are useful in eczema.
Action: We will continue to use short courses of oral antibiotics for children with overtly infected eczema. We will not use or recommend topical corticosteroid/antibiotic combinations, antibacterial or silver textiles, bleach baths or long term antibiotics in people with clinically infected or non-infected eczema until better evidence becomes available.