It is well-known to people with eczema, and clinicians who care for them, that finding appropriate clothing makes a huge difference to their skin and general well-being. Over the past ten years silk clothing has been shown in several small studies to be effective in improving eczema symptoms. It therefore came as a surprise to see headlines earlier this year proclaiming that silk clothing was not useful in eczema. Closer inspection of the study in question (CLOTHES) showed that this was not the whole story, underlining the importance of examining the details before uncritically accepting a journalist’s headline.
CLOTHES was a pragmatic study that compared usual care alone with usual care plus silk clothing to determine whether use of silk clothing improved moderate–severe eczema symptoms. Pragmatic studies are important because they are designed to assess the performance of a treatment in ‘real life’ situations – in patients who would normally receive the treatment.
Delving into the detail of this study, we can see that at entry, patients barely reached the ‘moderate eczema’ category with a mean eczema area and severity (EASI) score of 9.2 – probably not the patients who would normally get the treatment in the National Health Service. Given that the minimum clinically significant change in EASI is 6.6, it is unlikely that this could be achieved. Two different types of silk garment were used – one made of sericin-free silk bonded to an antimicrobial and one made of sericin-free silk coated with a polymer substance. (Sericin is a potential allergen that is removed from silk for surgical sutures.) The results showed that patients wore the garments for less than optimal times. In fact, the criterion for adherence in this study was wearing the garments for 50% of the day or night. Nearly 60% of patients only wore them for 50% of the nights or less, that is, 25% of the time. Given that manufacturers recommend whole-day use as skin-textile contact is critical for effectiveness, it is surprising that such a low level of adherence was accepted.
Even under these very challenging conditions, the patient-assessed outcomes (using the patient-oriented eczema measure (POEM) that, unlike EASI, includes itching and sleep loss) showed significant improvement in eczema while using the silk garments, but the EASI score showed no difference. Arguably, the POEM is the more important outcome in a pragmatic study. Conceivably, if patients with more severe disease had been included and better supported during the study, the EASI results would have been different – and positive headlines would have resulted. The authors acknowledge this in the discussion but sadly the message that has been picked up is a negative one.
What can we learn from this? Headlines often do not tell the whole story. Since the beginning of the evidence-based medicine movement, students and practitioners have been taught to examine studies carefully before basing decisions on the published conclusions alone. This continues to be an important guiding principle. Pragmatic studies are undertaken to provide evidence for policy makers and purchasers of healthcare, and it would be deeply regrettable if people with eczema were denied access to clothing that enables them to function without intolerable itching or debilitating sleep loss because of a misplaced reliance on headlines.