Abstract: We included 12 studies (784 participants) in this review; sample sizes ranged from 10 to 187 participants (median 56.5). One study had three arms that were all relevant to this review and all the other studies had two arms. One study was a within-participant comparison. All studies were industry funded. Two studies provided unpublished data for healing. Nine of the included studies compared PMM treatments with other treatments and reported results for the primary outcomes. All treatments were dressings. All studies also gave the participants compression bandaging. Seven of these studies were in participants described as having 'non-responsive' or 'hard-to-heal' ulcers. Results, reported at short, medium and long durations and as time-to-event data, are summarised for the comparison of any dressing regimen incorporating PMM versus any other dressing regimen. The majority of the evidence was of low or very low certainty, and was mainly downgraded for risk of bias and imprecision. It is uncertain whether PMM dressing regimens heal VLUs quicker than non-PMM dressing regimens (low-certainty evidence from 1 trial with 100 participants) (HR 1.21, 95% CI 0.74 to 1.97). In the short term (four to eight weeks) it is unclear whether there is a difference between PMM dressing regimens and non-PMM dressing regimens in the probability of healing (very low-certainty evidence, 2 trials involving 207 participants). In the medium term (12 weeks), it is unclear whether PMM dressing regimens increase the probability of healing compared with non-PMM dressing regimens (low-certainty evidence from 4 trials with 192 participants) (RR 1.28, 95% CI 0.95 to 1.71). Over the longer term (6 months), it is also unclear whether there is a difference between PMM dressing regimens and non-PMM dressing regimens in the probability of healing (low certainty evidence, 1 trial, 100 participants) (RR 1.06, 95% CI 0.80 to 1.41). It is uncertain whether there is a difference in adverse events between PMM dressing regimens and non-PMM dressing regimens (low-certainty evidence from 5 trials, 363 participants) (RR 1.03, 95% CI 0.75 to 1.42). It is also unclear whether resource use is lower for PMM dressing regimens (low-certainty evidence, 1 trial involving 73 participants), or whether mean total costs in a German healthcare setting are different (low-certainty evidence, 1 trial in 187 participants). One cost-effectiveness analysis was not included because effectiveness was not based on complete healing. The evidence is generally of low certainty, particularly because of risk of bias and imprecision of effects. Within these limitations, we are unclear whether PMM dressing regimens influence venous ulcer healing relative to dressing regimens without PMM activity. It is also unclear whether there is a difference in rates of adverse events between PMM and non-PMM treatments. It is uncertain whether either resource use (products and staff time) or total costs associated with PMM dressing regimens are different from those for non-PMM dressing regimens. More research is needed to clarify the impact of PMM treatments on venous ulcer healing.

Plain-language summary: In September 2016 we searched for as many relevant studies as we could find that had a reliable design (randomised controlled trials) and had compared PMM treatments with other treatments for venous leg ulcers. We found 12 studies involving a total of 784 people. Ten studies gave results we could use and all treatments were dressings. All these studies gave all the participants compression therapy as well as the dressings. Most of the people in the trials had wounds that were not getting better or had been there a long time. Findings from four trials are unclear as to whether there is a benefit of PMM dressings on venous ulcer healing compared with other dressings. Five trials reported on wound side effects and their results are unclear as to whether there is a difference in rates of side effects between PMM dressings and other dressings. It is also unclear whether PMM dressings result in decreases in the amount of saline used and the time taken during dressing changes, and whether there is an effect on total costs. Overall, the certainty of the evidence was judged to be low: most studies we found were small and could have been better conducted, so it was difficult to be sure how meaningful the results were. The next step would be to do more research of better quality to see whether PMM dressings do heal venous ulcers more quickly than other dressings. This plain language summary is up to date as of September 2016.