John: Hello, I'm John Hilton, editor in the Cochrane Editorial and Methods department.  Venous leg ulcers are the most common type of lower leg wound, affecting up to three people in every 1000 in some studies. Gill Norman from the University of Manchester in the UK, and colleagues, looked at the trials of dressings and topical agents in a new Cochrane Review in June 2018, and we asked Gill to outline their findings in this podcast.

Gill: Venous leg ulcers are open skin wounds caused by problems with the blood flow back up through the veins in the leg. They are often painful and slow to heal, and treatment often involves compression from stockings or bandages, which are usually combined with a wound dressing.
Several different types of dressings are available, from simple gauze to more advanced gels and films. There are also specialist dressings that contain ingredients such as silver and dressings aimed at altering enzyme activity in the wound. Creams or other treatments that can be applied to the ulcer may also be used, instead of a dressing. We studied the effects of this variety of interventions on complete healing of venous leg ulcers, which patients have told us is the most important outcome to them.
We found 78 randomised trials of different dressings or topical agents, with a total of just over 7000 participants and we did a network meta-analysis to simultaneously compare multiple treatments across different studies. We were able to include 59 of the studies in this, with nearly 5200 participants and 25 different interventions, but the evidence as a whole was considered to be low certainty. This means that our conclusions may change substantially if further research becomes available. 
The large number of treatments for relatively few participants meant that most treatments in our analysis had low probabilities of being the best. However, the two most likely to come out on top were silver dressings and sucralfate. But, the direct evidence for sucralfate was from a single small study with a particularly unusual result and we need to be extremely cautious about this finding. 
With regard to silver dressings, these seem likely to increase the probability of complete healing compared to nonadherent dressings, based on moderate certainty evidence but this still needs to be seen in the context of the overall low certainty of the network meta-analysis.
In summary, despite nearly 80 trials, there isn’t enough robust evidence to know which particular dressing or topical agent most improves the probability of healing in venous leg ulcers. Therefore, practitioners and patients choosing between these should consider the findings of our review as well as factors such as the cost of dressings, their management properties and patient preferences. In thinking about the research that is needed to strengthen the evidence base, future trials need to be designed to answer questions that are important to people affected by venous leg ulcers and those who treat them.

John: If you would like to see the detailed information gathered by Gill and her co-reviewers on the existing 78 randomised trials, and the methods and findings for their network meta-analysis you can find it with a search for 'Cochrane and treating venous leg ulcers'.