Right off the top, I apologize for the obviousness of the Mr. Spock reference. I couldn’t resist! A few months ago I was invited by Robert Kirsner, MD, PhD and Stephanie Wu, DPM to write a chapter on “Antimicrobial Therapy” in their upcoming Wound Healing Society Yearbook. The design of the chapter is a review of a recently published primary study and 2 or more secondary studies. Although I was extremely familiar with the primary topic, the randomized controlled trial on pexiganin vs. ofloxacin by Ben Lipsky, MD, one of the secondary papers really struck a chord with me. The study in the British Journal of Surgery by Micahels, et al out of the UK reported on the VULCAN trial, a large randomized trial looking at the use of silver dressing in venous leg ulcerations (VLU) http://www.ncbi.nlm.nih.gov/pubmed/19787753
This study of 213 recruited patients not only looked at wound healing differences between silver containing dressings and non-silver low adherence dressings in the treatment of VLU but also the cost effectiveness of the two. The primary measure was complete ulcer healing at 12 weeks with secondary measures being; time to healing, quality of life and the aforementioned cost-effectiveness. Although I do have some issues with the study design including the leeway given in dressing selection, compression definition and number of visits, I do find the results interesting.
As one might reasonably expect given the paucity of good evidence on the effectiveness of silver dressings as a class, the VULCAN study found that there were no significant differences between dressings in the number of ulcers healed at 12 weeks (59.6% silver, 56.7% non-sliver) nor to median time to healing. As could also be expected, silver dressings cost significantly more to use ($46.60 vs. $8.70 as converted from the reported £). The authors concluded that “There was no evidence to support the routine use of silver-donating dressings beneath compression for venous ulcerations”.
This finding won’t surprise anyone who has heard me lecture on “Differentiating infected from non-infected wounds” as I did at the APMA meeting, who has read the chapter on Diabetic Foot Infections in the 3rd Edition (specifically page 120), or has read my blog post from March 3, 2010 entitled “Bioburden and Wound Healing”. Silver dressings are everywhere. Just about every wound healing product line includes a number of silver donating products in every imaginable format. Yet, there is little to no evidence to support that they are of any benefit in wound healing or preventing wound infection. This revelation first came to me upon reading the Cochrane Collaborative systematic review of the literature on silver dressings which, like the VULCAN trial, found little evidence to support their routine use. This does not mean I don’t use them. Like most clinicians, if I see a heavily colonized wound I am seemingly genetically programmed to reduce the bioburden and kill the bugs.
What I am saying is that we should be practicing evidenced based medicine and not costing our patients or the health care system dollars that none of us can afford to spend on a therapy without solid science behind it. So, next time a sales rep comes to speak to you about their latest and greatest silver product, ask for scientific proof, not some pretty “before and after” pictures, that it contributes to wound healing. Unfortunately, I doubt you will get much. These products are all approved by the FDA as 510k medical devices. Therefore, there is little clinical science necessary to get them approved.
Lipsky BA, Holroyd KJ, Zasloff M. Topical versus systemic antimicrobial therapy for treating mildly infected diabetic foot ulcers: a randomized, controlled, double-blinded, multicenter trial of pexiganan cream. Clin Infect Dis. 2008;47:1537-45.
Michaels JA, Campbell B, King B, Palfreyman SJ, Shackley P, Stevenson M. Randomized controlled trial and cost-effectiveness analysis of silver-donating antimicrobial dressings for venous leg ulcers (VULCAN trial). Br J Surg. 2009;96:1147-56.