More evidence needed for eczema bath oils

Bath products commonly used to help relieve ”dry itching skin” caused by eczema may not work, reported the Daily Mail and BBC News. “The [bath] oils are designed to prevent water loss from the skin and form a protective barrier”, the Daily Mail said. Both stories report that researchers calculated the annual cost covered by the NHS for such “emollients” – £16 million – and concluded that this may be a waste of money.

The stories are based on an article which concluded that there is more evidence that moisturisers (lotions, creams, gels and ointments) applied directly to the skin are effective in eczema than there is for the use of emollients in the bath (bath oils and other products). They conclude that treatment using directly applied moisturisers without ever using products in the bath “is entirely reasonable”.

Where did the story come from?

The study was published as a commissioned article and was peer-reviewed in the journal Drug and Therapeutics Bulletin (DTB). The aim of the DTB is to provide impartial advice to healthcare professionals about treatment. It is written by experts in the topic areas chosen.

What kind of scientific study was this?

DTB’s articles aim to reflect the state of the literature and offer an expert consensus on the efficacy of treatments. Articles, though written by an expert, are anonymously published and represent the view of the DTB as an independent, unbiased provider of information about drugs and their context in medical practice.

What were the results of the study?

The authors describe the published evidence for the use of moisturisers applied directly to the skin and then discuss the evidence for bath products. They describe one randomised controlled trial in which directly applied moisturisers reduced the need for additional use of steroid creams (another treatment for eczema) when compared with not using the moisturisers, in infants under a year old. Though this study has its limitations (the fact that researchers and parents knew that they were getting the treatment, i.e. were not “blinded”), it appears to be the only available evidence for this treatment. The authors say that there is no published information on studies that have been carried out to see whether bath products work or not.

What interpretations did the researchers draw from these results?

The authors say that despite the fact that bath products are often prescribed to treat or relieve the symptoms of eczema, there is no evidence that they make any “clinical contribution”. They call for a proper evaluation of these treatments and say that in the absence of evidence that they do work, “treatment strategies in which patients successfully apply emollients to the skin without ever using bath emollients are entirely reasonable”.

What does the NHS Knowledge Service make of this study?

This article is a narrative round-up of the literature and expert opinion about the use of emollients for treating people with eczema (atopic). The particular focus is on the apparent absence of evidence for using bath products. We would support the call for a more formal evaluation of the evidence for and against this treatment.

It is unclear from this article how the randomised trials discussed were identified and if this was a systematic process. A systematic review of the relevant studies would give us a clearer picture of where we stand. The large expenditure by the NHS mentioned by the authors could hardly be justified if such a review found no evidence to support the use of the bath products in this way.

Eczema sufferers should consider consulting their doctor before changing the way they manage their symptoms.

Sir Muir Gray adds...

It was National Eczema Knowledge Week in the excellent National Library for Health - Skin Disorders on 17th–21st September 2007 and that is the place to look for effective treatments for this common, distressing condition.