Shaky Evidence for an Old Technique
Abstract & Commentary
By Allan J. Wilke, MD, Residency Program Director, Associate Professor of Family Medicine, University of Alabama at Birmingham School of Medicine—Huntsville Regional Medical Campus, Huntsville. Dr. Wilke reports no financial relationship to this field of study.
Synopsis: The use of a steroid ointment following a 20-minute soak may relieve chronic skin conditions.
Source: Gutman AB, et al. Soak and smear: a standard technique revisited. Arch Dermatol. 2005;141:1556-1559.
This is a retrospective study of 28 patients with severe atopic dermatitis, xerosis, or chronic hand dermatitis. These patients attended a medical school dermatology clinic that specialized in difficult cases. After identifying 34 cases that fit their profile, the authors excluded 6 patients, 5 for lack of follow up and 1 for lack of a medical record. The 14 men and 14 women who remained ranged in age from 24 to 84 years. They all had failed numerous topical regimens and most had also taken prednisone or cyclosporine or had UV-B treatment. A combined patient-physician global assessment (complete clearance or percentage of improvement) was the outcome of interest. Each patient was instructed in an aggressive "soak-and-smear" therapy, which consisted of bathing in plain hot water for 20 minutes at night and then smearing an intermediate-potency steroid ointment (usually triamcinolone acetonide [TCA] 0.1%, however, the authors were not explicit about this) over the affected areas without drying. (A detailed patient educational instruction sheet is presented in the article.) The patients did this for up to 2 weeks at which point the responses were complete (17), 90-100% improvement (9), 80% improvement (1), and 75% improvement (1).
When study results appear too good to be true, they probably aren't. There are several methodological flaws in the design of this study which raise important questions, so its conclusions must be viewed with some skepticism. First, it was a retrospective study. The patients were not randomized to an intervention group or a control group. Would the patients have done as well with an aggressive program that substituted petrolatum for the TCA ointment? How about bear grease? The patients were referred to this tertiary center because they had failed conventional therapy. Are they representative of the patients you see? Five patients were excluded because they did not follow up. Did they not return because the treatment failed? The wide age range could be a problem because aging changes skin. Older patients produce less sebum, which is the body's natural moisturizer.1 Were the authors treating heterogeneous conditions? The outcome measure is very subjective. For instance, what exactly would 50% improvement look like?
The gentle reader might now wonder, "If this is such a poorly done study, why should I consider this therapy for my patient?" I think you should consider it for 2 reasons. The first is that its mechanism of action is intuitively plausible: hydrate the stratum corneum and then seal in the water with petroleum jelly. If there is some element of inflammation, all the better. The TCA penetrates hydrated stratum corneum better than dehydrated stratum corneum. The second reason is that this regimen satisfies most of the STEPS2 mnemonic: Safety, Tolerability, Effectiveness, Price, and Simplicity. Water and petrolatum have very benign safety profiles. TCA could cause dermal thinning or systemic side effects, if used for a prolonged period of time. However, the 2-week course of therapy proposed here is unlikely to cause any major adverse effects. Tolerability could be an issue since ointment is messy, but since the advice is to use it at night and to wear old pajamas, the messiness is minimized. If you believe this study, "soak and smear" is a very effective regimen. The treatment is cheap; an 80-gram supply of TCA 0.1% ointment is available online for less than $8.00.3 Even in our immediate gratification society, two weeks of a 20-minute bath and application of ointment seem like simplicity itself.
1. Cerimele D, et al. Physiological changes in ageing skin. Br J Dermatol. 1990;122(Suppl 35):13-20.
2. Scow DT, et al. Combination therapy with ACE inhibitors and angiotensin-receptor blockers in heart failure. Am Fam Physician. 2003;68:1795-1798.
3. www.americarx.com. Accessed January 24, 2006.