Does Iodine Impede Wound Healing?

Dr. Christopher Girgis shares an overview and insights from their literature review, “Medical Mythology, Misconceptions and Misinformation: Does Iodine Impede Wound Healing?” Coauthors include Mehmet A. Suludere, MD; P. Andrew Crisologo, DPM; and Lawrence A. Lavery, DPM, MPH. Read the full paper here.

Transcript:

Hello, my name is Christopher Girgis, and at the time this article was written, I was a diabetic limb salvage fellow at the University of Texas Southwestern Medical Center. Now I'm currently an attending podiatrist at the University of Michigan. It is my pleasure to discuss with you this study titled, Medical Mythology, Misconceptions, and Misinformation: Does Iodine Impede Wound Healing?

So as an introduction, povidone iodine, abbreviated PI, has been shown to be an effective modality against a broad spectrum of bacteria and to be cytotoxic to a variety of cell types, as demonstrated by a variety of in vitro studies. Such findings led to the widespread belief that povidone iodine interferes with wound healing. So this study sought to review laboratory studies, animal wound studies, and clinical studies that examine the efficacy and safety of iodine-based wound products in wound healing. So to accomplish this goal, we searched PubMed and Scopus databases without time restrictions.

We searched the following terms: iodine, Betadine, cadexomer iodine, povidone iodine, diabetic foot ulcer, venous leg ulcer wounds, and randomized clinical trial. The search included human and animal studies, and then a total of 15,146 articles were identified. We then reviewed the abstracts for eligible studies and retrospective studies, and articles that did not evaluate pressure ulcers, diabetic foot ulcers, and venous stasis ulcers or surgical wounds were excluded. A total of 62 articles were identified for complete evaluation. Those studies were then divided into in vitro studies, animal studies, human studies, and randomized controlled trials of povidone iodine and cadexomer iodine. We identified 14 randomized clinical controlled trials and 5 comparative studies that evaluated povidone iodine and 14 randomized controlled trials that evaluated cadexomer iodine.

What we found was that, in 63% of the studies, there was no difference between povidone iodine and controls, and in 5% of the povidone iodine studies, povidone iodine performed significantly better than the comparator, and 31% of the studies, outcomes were significantly better with the comparator than with povidone iodine. In the randomized controlled trials evaluating cadexomer iodine, 64% of the studies found no difference between cadexomer iodine and the comparator; 35% showed significantly positive influence of cadexomer iodine compared with controls.

So in conclusion, both cadexomer iodine and povidone iodine appear to be a safe modality with no evidence that these products impede wound healing, are associated with more infections, or require more amputations compared with other modalities. Povidone iodine can effectively be used for short periods of time, and cadexomer iodine is an effective wound modality for chronic wounds.

We were prompted to create this study because the use of iodine to manage wounds is a very controversial topic, and many healthcare professionals have closely held beliefs that iodine damages wounds and impedes wound healing, but they often do not know the foundation of or have evidence for this belief. So then this medical mythology oftentimes affects clinical behavior. So we sought to assess the validity of this sentiment and to see if iodine based products do in fact impede wound healing.

The most surprising result was that the majority of the povidone iodine studies showed no difference between povidone iodine and controls in majority of the cases. And in one study, povidone iodine actually performed better than the comparator. So we found that iodine based products were in fact safe, that they did not impede wound healing, were not associated with more infections, and did not require more amputations compared with modalities. So this was particularly interesting because the findings present in the lab raising concerns for cytotoxicity do not appear to translate to impaired clinical outcomes.

After this review, I see 2 major opportunities for further research, which would include larger randomized controlled trials that evaluate povidone iodine with other wound care modalities. For the studies available to us in this review, the number of subjects in each treatment arm was less than or equal to 40 in majority of the studies, 68.4% of the povidone iodine studies, so there is certainly room to evaluate povidone iodine in relation to other wound care modalities with larger randomized controlled trials.

The second opportunity for research that can be pursued are studies that evaluate povidone iodine and cadexomer iodine as they relate to infection rate. As the article discusses, povidone iodine and cadexomer iodine have demonstrated effective abilities to kill a broad spectrum bacteria in the lab, which theoretically would also result in faster healing and fewer infections. However, in the studies that we evaluated, only 2 studies reported infection as an outcome in randomized controlled trials. So there is certainly room for additional studies that examine the clinical outcome of infection using these modalities to see if the broad spectrum of bacterial activity demonstrated by iodine based products in the lab translates to clinical outcomes of infection.