Dr John Loughnane looks at the recent guidelines, issued by the UK’s National Institute for Health and Clinical Excellence, on the treatment of atopic eczema in children
Atopic eczema (AE) is a chronic, relapsing, pruritic dermatosis, with a tendency to favour flexural areas. It is most likely caused by a mixture of genetic predisposition, host immune responses, skin barrier dysfunction, infectious agents and environmental factors. It usually presents as a red, scaly rash that is especially prominent on the forehead and cheeks of babies from the age of about six weeks. The skin is dry and the main symptom is itch.
With time, the rash spreads to the body and limbs. Lesions favour the flexures, especially the antecubital and popliteal fossae, and the creases of the buttocks and thighs. Constant scratching and rubbing produces redness, scaling, excoriations and skin thickening.
Atopy is an inherited ability to develop an Immunoglobulin E-mediated (IgE-mediated) response to certain allergens. Some 80 per cent of eczema patients have raised levels of IgE, leaving 20 per cent who do not and are by definition not atopic, suggesting that there is more to eczema than allergy.
Eczema is predominantly an inherited condition, although the exact genetic pattern of inheritance is not clear. If one parent is affected, there is a 60 per cent chance of an offspring having the condition. The risk rises to 90 per cent when both parents are affected.
In recent years, it is increasingly recognised that a defective skin-barrier function is the primary underlying problem in eczema. The damaged skin barrier allows water loss, leading to drying and shrinking of surface skin cells. Irritants, allergens and bacteria are thus allowed penetrate the skin barrier.
Irritants further damage the lipid layer. Allergens stimulate IgE production, producing inflammation. Bacteria release toxins that provoke an exaggerated allergy response (so-called superantigens).
It is obvious that restoration and preservation of an effective skin barrier is vital to effective management of eczema.
Food allergens
Dietary allergy is often incriminated in eczema. In most cases, dietary manipulation will already have been tried by patients. Suspect a food allergy in eczema patients only in certain, specific instances, such as where there is:
l Severe disease that is refractory to optimum management;
l History of immediate reaction to food, especially in the area of contact around the mouth;
l Gastro-intestinal problems – colic, vomiting, altered bowel habit, failure to thrive.
There is no really reliable test for food allergy in eczema. Skin-prick testing is not good at detection. Radioallergosorbent (RAST) blood testing for specific allergens is often undertaken. There is, however, a high false-positive and false-negative rate for these tests.
Dietary manipulation
The National Institute for Health and Clinical Excellence (NICE) has issued guidance on dietary manipulation. Soya formula should not be tried before six months of age, as it has a higher risk of allergic reaction than has cows’ milk protein. There is some evidence that an eight-week trial of extensively hydrolysed protein formula or amino acid formula, in place of cows’ milk formula, may help.
Always refer to a dietician if considering their use beyond six weeks. Goats’ milk protein is similar to cows’ milk protein and is therefore not recommended.
Suspected foods should be reintroduced to the diet after the age of three years, when most patients should have no further problems with it. They have usually grown out of their food allergy by then. Allergies to nuts or shellfish tend to persist into adult life, however.
Emollients
As outlined above, a defective skin barrier is the most important feature needing attention in the treatment of eczema. Emollients are greasy substances that form an artificial barrier on the skin. Water is trapped and retained in the skin. With water retention, the skin is more flexible and medications penetrate more effectively. Penetration of bacteria, irritants and allergens is reduced.
Emollients are best applied as part of a moisturising bath regime. Soak for 20 minutes in a tepid bath, to which nothing has been added but an emollient. Soaking for this length of time is necessary to rehydrate the surface skin cells. On getting out of the bath, the skin is rapidly covered in as greasy an emollient as the patient finds tolerable.
This layer of emollient traps water in the superficial skin layers. A good choice for most patients is emulsifying ointment, which is generally acceptable on skin saturated with water in this way.
Moisturisers
Moisturisers need to be applied several times daily, in addition to the above. Once eczema has been controlled with topical steroids, it is essential that a regime of regular moisturiser use be put in place to maintain remission and reduce the frequency of acute flare-ups.
If patients find ointments unacceptable during the day, a possible compromise might be to use an ointment at night with a more acceptable cream moisturiser used during the day.
Moisturisers come as lotions, creams and ointments, depending on their lipid content. Lotions have the lowest lipid content and creams have intermediate content, with ointments having the highest.
Generally, the greasier the emollient, the more effective it is. However, very greasy preparations may not be acceptable to all patients. Creams are more acceptable than ointments, but need to be applied more generously and more often. As most eczema presents in the chronic, dry stage, moisturising ointments are better than creams.
Staphylococcal infection
In eczema patients who suffer recurrent staphylococcal infection, antiseptic bath emollients are sometimes suggested. The antiseptic benzalkonium is contained in Oilatum Plus (6 per cent) and Emulsiderm (0.5 per cent). There is, however, no firm evidence base to support their use.
Urea is added to some moisturisers. Urea penetrates the skin and attracts water. It is contained in Itch Relief Cream from E45, Calmurid and Eucerin. Urea-containing moisturisers are particularly useful in thick, hyperkeratotic eczema, which is more often found on the limbs.
Areas around the eyes and eyelids are sensitive and a combination of soft paraffin and liquid paraffin mixed 50/50 (paraffin gel) may be better tolerated. Epaderm has recently become available in Ireland and is acceptable to many patients, but is a little expensive and not available on the GMS.
Aqueous cream gives a stinging sensation in over 50 per cent of children with eczema. It should not be used as a leave-on emollient, although it is an acceptable soap substitute.
Topical steroids
Topical steroids are the mainstay of treating atopic eczema. They are not curative and suppress the eczema only as long as their use is continued. They are classified according to potency. One should become familiar with one preparation from each potency group.
The classification of topical steroids is as follows:
l Mild – hydrocortisone, 1 per cent;
l Moderate – clobetasone butyrate (Eumovate); alclometasone dipropionate (Modrasone);
l Potent – betametasone valerate (Betnovate); betametasone dipropionate (Diprosone), hydrocortisone butyrate (Locoid); mometasone furoate (Elocon).
l Very potent – clobetasol propionate (Dermovate).
The main side-effect to worry about is skin thinning. Infants and children have thin skin that is more susceptible. At all ages, skin on the face (especially around the eyes), on the genitalia and in the axilla and groin is thin and only mild- or moderate-potency steroids should be used in these areas.
When treating an acute flare of eczema, hydrocortisone is safe to use on the face in babies and children, with a moderately potent steroid on the body. The recent NICE guidelines suggest potent topical steroids could be used in children, provided the child is over the age of one year. Treatment is limited to seven days and not applied to the face.
In adults, a moderately potent steroid may be used on the face while a more potent preparation is used, for short periods, on the body. Once the disease is well under control, the potency of the steroid may be reduced as soon as possible – the step-down approach. Emollients at full dosage should be continued at all times.
Twice-daily application of steroid is no longer advised, as it is no more effective than once daily. The patient should be advised to apply one generous layer daily. Directions included in packaging tend to emphasise a thin layer of steroid only.
Cream formulations of topical steroids should be used if eczema is oozing. They help dry the eczema. However, the majority of eczema that we see is chronic and dry. Ointment formulations, with their good moisturising effect, are more suitable.
Indeed, steroid ointments may be a very acceptable moisturiser and patients should be advised to avoid using a topical steroid as an emollient. When treating a disease flare, a steroid is applied to the inflamed skin, with emollient applied to non-inflamed areas.
Infection in atopic eczema
About 90 per cent of patients with eczema are colonised with Staphylococcus aureus (SA), which rarely colonises non-eczematous skin. The degree of SA colonisation correlates with the level of disease activity. Signs suggesting that infection is exacerbating eczema should be looked for.
Clinically, SA leads to the development of sore, fissured and weeping skin. The best way to avoid infection is good disease control, leading to maintenance of a good skin-barrier.
SA produces toxins that act as superantigens, which greatly promote the eczematous response.
The features of infected eczema are: worsening of eczema, getting redder and sore; weeping; yellow crusting; fissuring – especially if painful; and pustules. Diagnosis of infection is based on clinical appearance, as swabbing the skin of a patient with active eczema almost invariably spreads SA.
Fucidic acid/antibiotic combinations (Fucibet, Fucidin HC) are popular and effective. Fucidic acid should not be continued for longer than 10 to 14 days at a time, to reduce the risk of resistance developing.
If fucidic acid resistance is a problem, consider steroid-antiseptic combinations such as vioform hydrocortisone or chlorquinaldol (Locoid C). Bacteria do not develop resistance to antiseptics. These antiseptic combinations may leave a yellow stain on the skin.
Milton baths
For severe infections, an oral antibiotic should be used – flucloxacillin 250 mg TID for 10 to 14 days. The branded product floxapen syrup is better tolerated by children. If infection is recurring, one might use Milton baths. Add 125ml of Milton to a bath half-full with water. This can be alternated every second night with a moisturising bath.
Many acute flares of eczema presenting in general practice are secondary to infection. The key to getting a good response is to use an antibiotic plus a topical steroid contemporaneously.
The best way to prevent future infection is to get the eczema under good control and keep it that way with an effective maintenance regime. The intact skin-barrier prevents future penetration and infection by SA.
Antihistamines
Histamine does not have an obvious role in the pathogenesis of eczema. Non-sedating antihistamine drugs have not been advised to treat eczema. If sleep is disturbed, a sedating antihistamine may be advised at night, e.g. trimeprazine (Vallergan) or hydroxyzine (Ucerax). It should be limited to seven to 10 days at a time, as there is a risk of tachyphylaxis, i.e. less and less response, with prolonged use.
The latest NICE guidelines suggest a one-month trial of a non-sedating antihistamine (Neoclarityn, Xyzal) if eczema is severe and accompanied by marked itch, hay fever, asthma or urticaria. If thought to be of benefit, they may be continued. Tachyphylaxis does not seem to be a problem with non-sedating antihistamines.
Topical immunomodulators
The most significant advance in treating eczema since the introduction of topical steroids has been the development of topical immunomodulators. There is only one available in Ireland – tacrolimus (Protopic). It is a calcineurin inhibitor. It is licensed for patients over two years of age.
The 0.03 per cent formulation is indicated for those under 16 years. For those aged over 16, the 0.1 per cent preparation may be used.
Points to remember when using tacrolimus:
l It is indicated for moderate to severe eczema that is unresponsive or intolerant of conventional therapy not adequately responsive to topical steroids plus emollients;
l It is as effective as a potent topical steroid;
l It is especially useful on the face, around the eyes and on the neck, i.e. areas at high risk of skin thinning from steroid use;
l It has been licensed for short term and intermittent use and, more recently, for twice weekly, long-term maintenance use;
l Some 20 per cent of patients experience a stinging sensation – this usually resolves in six days. Stinging tends to recur on future reintroduction;
l Thick, very lichenified eczemas tend not to respond very well;
l Skin infection must be cleared prior to use, especially herpes simplex and staphylococcus;
l Sun protection should be advised. Sun protection cream may be applied 20 minutes after tacrolimus application;
l Avoid in pregnancy.
In the US, the Food and Drugs Administration issued an alert to healthcare professionals regarding the potential link between topical tacrolimus and skin cancer and lymphoma.
An expert consensus concluded that this alert was unjustified and caused unnecessary anxiety and confusion. The alert does emphasise the importance of prescribing tacrolimus appropriately.
NICE guidelines recommend consideration of paste bandaging and wet wraps, which cannot be elaborated upon in this article as space prohibits.
Eczema that frequently recurs (despite good moisturiser use) and infection control may still be a problem. Twice weekly long-term maintenance use of either a topical steroid or tacrolimus, applied to the areas prone to flares, may help. Tacrolimus now has a product licence for such use.
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