Food allergies are more likely in the youngest patients
For about a third (35%) of children with AD, the trigger is a food allergy.22 This is most common in infants, with one study showing a peak at 18 months.20,24 The most common food allergens are milk and egg, but wheat, soy, and peanuts are potential allergens, as well.22,25 Food allergies, which are difficult to identify, should be suspected in patients with a poor response to first-line treatment. Sensitivity testing with food challenge may be worthwhile only in severe cases that are refractory to routine care.20
We caution parents not to attempt to withhold a suspected food allergen on their own. To avoid the risk of malnutrition, young children should be placed on elimination diet trials only if the allergen has first been identified by sensitivity testing and food challenge tests, because the allergen may not be clinically significant.21,22 Neither skin prick tests nor serum tests for allergies have been found to be accurate, and parents themselves are often mistaken. Several studies have found a discrepancy between the foods parents think their child is allergic to and the substances that are later found to be clinically significant allergens.21
CASE 1 You advise Dylan’s mother not to switch formulas because answers to further questions about other symptoms were unremarkable (eg, diarrhea). Dylan is treated with a low-potency (class VII) topical steroid (1% hydrocortisone cream) with instructions for the parents to maintain hydration and call you in 5 to 7 days.
Topical corticosteroids are first-line treatment
Two major classes of pharmacologic agents are used for the treatment of AD: topical corticosteroids and topical calcineurin inhibitors (TCIs). Corticosteroids are first-line treatment, as their clinical effectiveness has been well established; TCIs are indicated only as second-line therapy.26,27
Which dosing regimen is best?
The potency of corticosteroids is expressed by a numerical scale, ranging from class I (the most potent) to class VII (the least potent). Class I steroids are about 1800 times more potent than class VII preparations.8
A decision about which strength to use is based on several factors, including the severity of the child’s AD, his or her age, and the affected body site. For infants ≤12 months old, the lowest potency preparations (such as 1% hydrocortisone) are preferable, but should be used in the diaper area for no more than 3 to 7 days at a time.8 In general, potent topical corticosteroids should not be used for children <12 months of age without a dermatology consult.8,9
For children ages 1 through 5 years, intermittent (1- to 2-week) bursts of mild to moderate potency corticosteroids (class VI and VII) are suitable; for older children, a 7- to 10-day course of more potent preparations (class II-V) can be used for nonflexural and nonfacial skin.
While clinical trials have addressed the issues of quantity, duration, potency, and frequency (one large systematic review found twice-daily application of topical corticosteroids to be no more effective than once-daily applications10), an optimal approach to their use in the long-term management of pediatric AD is largely undefined. Various approaches include:
- starting with a more potent preparation to induce remission, followed by a less potent corticosteroid as the AD improves
- using short bursts (5-7 days) of a potent topical corticosteroid, followed by emollient use until a flare-up occurs
- relying on prolonged, or continuous, treatment with less potent preparations.11,23
Long-term use of topical corticosteroids of any potency should be avoided in areas of high risk for cutaneous side effects, such as the face and intertriginous areas.
Emollients are also an important part of therapy for all pediatric patients. Emollients help restore the integrity of the skin barrier and inhibit water loss,1,2,12,20 and should be used not only during an acute flare, but also for maintenance therapy. Tell parents to look for emollients that are unscented and contain fewer additives, and to apply the emollient at least twice daily, and after bathing or swimming.5,20
CASE 2 You prescribe a class V steroid (triamcinolone ointment 0.025%) for Angela, to be applied once a day for 5 to 7 days. You instruct her mother in basic skin care and stress the importance of using an emollient regularly, not just during a flare-up.