Sometimes the simplest ideas are the best. by Dr Rupert Mason

In the league table of publicly perceived nasty diseases, skin problems come towards the bottom. They don’t seem to have the emotional pull of cancer or multiple sclerosis. Yet any family of a child with severe atopic dermatitis knows only too well how very nasty it can be. And any health professional with experience in dermatology would pick atopic dermatitis as one of the eight diseases not to take on a desert island.

Atopic dermatitis is a chronic relapsing inflammatory skin disease that usually starts during the first years or months of life. One crucial aspect of the disease is that it impairs the barrier function of the epidermis. This can result in increased transepidermal water loss and the penetration of environmental allergens into the skin which set off immunological reactions and inflammation. In addition, the stratum corneum is highly susceptible to colonisation by various bacteria, mainly Staphylococcus aureus. It is believed that this overgrowth with S. aureus exacerbates or contributes to skin inflammation by secreting superantigens which further activate inflammatory cells. The degree of colonisation has been shown to be associated with disease severity and for this reason topical and oral antibiotics are often used to keep atopic dermatitis under control as well as emollients, steroids and immunomodulators.

An intriguing recent development in the control of atopic dermatitis is the prospect of novel clothing materials which claim to benefit the wearer.

Firstly there are “hi tech” fabrics impregnated with antimicrobial agents such as silver ions or triclosan which leech out of the fabrics and onto the skin. Silver has recognised antimicrobial properties and some studies have investigated the possible benefits of silver impregnated fabrics with eczema but the case for them is still unproven. There are also concerns about the development of bacterial resistance with both these agents and the effect of accumulation of the agents in the body. Also there are the local and environmental effects of silver which have resulted in Sweden’s State run Pharmacy, Apoteket banning the sale of silver impregnated dressings.

However, a material with a non-migrating antimicrobial which killed bacteria on contact but did not transfer to the skin of the patient could still theoretically be beneficial.

S. aureus is by no means the only aggravating factor in atopic dermatitis. Others include climatic factors, inhaled allergens, stress, and chemical and physical irritants. Control of these factors is important for effective management of the disease. With regard to clothing it is particularly important to choose a garment which at least does not aggravate the condition, and at best helps to control it.

Types of Fabric

The options are synthetic or natural fabrics. Synthetic fabrics are produced by the chemical processing of petroleum. These materials have a number of practical advantages such as stable colouring and durability and can be designed to wick away excess moisture, but they are not the fabric of choice for atopic skin. Nylon, for example can cause allergic contact dermatitis and contact urticaria. One study compared the irritative capacity of three different synthetic materials to cotton. The results showed that the synthetic materials caused significantly greater itch and discomfort than cotton in patients with atopic dermatitis.

Natural fabrics are derived from either plant fibres, eg cotton and linen, or animal fibres, eg wool and silk. Their individual properties are important in determining whether they are suitable for use on atopic skin.

Wool fibre has frequently been shown to be irritant to the skin of atopic patients, and the intensity of itching from wool fibres has been shown to increase in relation to the physical characteristics of the type of fibre.  Wool is generally avoided as a choice of undergarment material.

Cotton 

Cotton is currently the most commonly used textile for patients with atopic dermatitis. It is relatively soft and naturally abundant. However, it is prone to bacterial and fungal attack, and has a crucial flaw in its structure. Cotton yarn is spun from many short (1-3cm) fibres with flat irregular sections. Whilst this is not a major problem in normal intact skin it can cause all sorts of issues with atopic skin. Temperature regulation can often be a major issue with atopic skin and many children with eczema overheat and sweat. When cotton comes into contact with moisture the short fibres within the thread extend and contract as they absorb moisture producing an abrasive rubbing movement that may irritate the skin.

Cotton fibres magnified x 76

Silk

Natural silk is a single thread secreted by Bombyx mori, aka the silkworm. It is made up of a double filament of protein material called fibroin which is glued together with a sticky substance called sericin. This natural silk is woven into the shiny fabric that we are all familiar with.

In contrast to the short stubby fibres of cotton, each silk thread is made up of filaments up to 800metres long and this produces a fabric that is perfectly smooth and does not cause friction on the skin.

However, the silk products that you can buy in the High Street have two disadvantages with regard to atopic dermatitis. First, they are made from a very tightly woven fabric which restricts the movement of air through it. 

Second, the sericin in pure natural silk has been linked to allergic reactions. This is why surgical silk, used in sutures utilises only the fibroin component of silk. The treated fibroin-based silk has virtually no allergenic potential and has been safely used as a suture material for many years.

Recently, a range of specialist clothing has become available made from medical quality, sericin-free silk. This takes the characteristic shine off the silky material but ensures that it is hypo-allegenic. More importantly, the fabric is knitted, not woven. This creates holes in the fabric which allow air and moisture to pass through it.

It also has greater ability to absorb moisture than cotton without feeling damp, and helps to maintain the body temperature by reducing excessive sweating and moisture loss. These properties make it a natural candidate for an atopic-friendly fabric.

Silk fibres magnified x 76

An interesting additional property is the incorporation of an “antimicrobial shield”. This technology involves permanently bonding a physical antimicrobial agent (AEM 5772/5) to the fabric. It was initially developed to protect operating theatre linen from bacterial contamination and has been in use for many years. As it does not leech onto the skin the risk of bacterial resistance is minimised.

In a study published in the British Journal of Dermatology, the clinical effectiveness of this material (DermaSilk) in the treatment of atopic dermatitis was reported. The overall severity of the disease was monitored using a validated scoring index (SCORAD). At the end of the study there was a significant decrease in the severity of atopic dermatitis in the silk group, but no significant change in the cotton group. The authors concluded that the use of silk clothes may be useful in the management of atopic dermatitis in children. A conclusion that has been supported by a number of other studies plus over 4 years of clinical experience in the NHS around the UK.

The next question on any self respecting administrator’s lips is “Is it worth the money?” The NHS is increasingly conscious of what it spends in all of its departments and it would be all too easy for these garments to be dismissed as incidental underwear but a closer examination of the effects that they can have on a family – both tangible and intangible turns the cost argument into a value message as a prescription for DermaSilk can actually save the NHS money AND improve the quality of life for a whole family affected by eczema. This could explain why DermaSilk is now included in the European Atopic Eczema Management Guidelines for mild to moderate eczema. The garments control temperature, humidity and itch, resulting in fewer flares and better managed eczema. As a result the child and the whole family sleeps better and the amount of prescription medication used on the child is reduced. Over the average lifespan of these garments (approximately 12 months) they save more than their cost in reductions of medication used and can significantly reduce the number of visits to the Surgery

At long last we have an evidence base to help us decide what is best to wear next to the skin with atopic dermatitis. Admittedly, the data are still not extensive by modern standards, and there is always a need for more. The current state of knowledge is that the use of cotton is essentially based on word of mouth with little evidence in terms of clinical trials. There is now good objective evidence to show that this specially treated silk is the fabric of choice for children and adults with mild to moderate atopic dermatitis.

Dr Rupert Mason has worked as a GP and Clinical Assistant in dermatology.