We cannot be certain whether hydrogel dressings are any more effective for healing of venous leg ulcers than other types of dressing such as gauze and saline, alginate, manuka honey or hydrocolloid. There was not enough information to be sure how hydrogel dressings compare with other dressings in terms of potential side effects.
What are venous leg ulcers?
Venous leg ulcers are wounds or sores on the leg caused by alterations in the circulation of blood in the veins. They are hard-to-heal wounds. Venous leg ulcers may cause pain, itching and swelling. There may be changes to the skin around the ulcer, and it may also produce fluids. The standard treatment for this type of wound is compression therapy (bandages or stockings) to improve blood flow in the legs. Dressings are applied underneath compression bandages to protect the wound and aid healing. Different types of dressings vary in their ability to: maintain a moist environment; absorb excess fluid from the wound; soften dead tissue; cushion the wound; keep the wound clean and free of germs and keep newly healed skin intact. Hydrogel dressings are filled with a watery gel and can be used to keep the wound moist; they are intended to help remove dead tissue and help healthy skin to grow.
What did we want to find out?
We wanted to find out if hydrogel dressings compared to other dressings:
– heal venous leg ulcers;
– have any unwanted effects;
– have any effect on changes in ulcer size, time-to-ulcer healing or recurrence of ulcers;
– improve people's quality of life;
– reduce pain;
– impact the costs of treatment.
What did we do?
We searched the medical literature and collected and analysed all relevant randomised controlled trials (clinical studies where the treatment people receive is chosen at random) to answer this question. This type of trial provides the most reliable health evidence. There were no restrictions on publication language, settings where treatments were used, or sex or age of the participants, as long as they had venous leg ulcers. We excluded trials evaluating hydrogel dressings impregnated with antimicrobial (which reduce the presence of bacteria), antiseptic (which stop or slow down the growth of germs) or analgesic (painkiller) agents as these interventions are evaluated in other Cochrane Reviews.
What did we find?
We found four studies dating from 1994 to 2008, involving 272 participants with an average age ranging from 55 to 68 years. Two studies provided no information on participants' sex and the other two included 29 women and 51 men. The studies investigated the use of hydrogel dressings for either two or four weeks. Hydrogel dressings were compared with gauze and saline (salt water), alginate, manuka honey or hydrocolloid.
– It is uncertain whether there is a difference in complete wound healing when hydrogel is compared with gauze and saline or manuka honey.
– It is uncertain if the incidence of wound infection is different between hydrogel dressings and manuka honey or whether there is difference between hydrogel and gauze and saline, alginate or hydrocolloid dressings in terms of change in ulcer size.
– None of the studies reported useable results for time-to-ulcer healing, recurrence of ulcer, health-related quality of life, pain and costs, so we cannot establish the impact of hydrogel on these outcomes.
What limited our confidence in the evidence?
Most studies were small (only one with more than 100 participants) and all used methods likely to introduce errors in their results. The duration of follow-up was short (ranging from two to 12 weeks) and studies were not designed to assess time to complete healing.
How up to date is the review?
We searched for studies published up to 10 May 2021.
There is inconclusive evidence to determine the effectiveness of hydrogel dressings compared with gauze and saline, alginate dressing, manuka honey or hydrocolloid on venous leg ulcer healing. Practitioners may, therefore, consider other characteristics such as costs and symptom management when choosing between dressings. Any future studies assessing the effects of hydrogel on venous wound healing should consider using all the steps from CONSORT, and consider key points such as appropriate sample size with the power to detect expected differences, appropriate outcomes (such as time-to-event analysis) and adverse effects. If time-to-event analysis is not used, at least a longer follow-up (e.g. 12 weeks and above) should be adopted. Future studies should also address important outcomes that the studies we included did not investigate, such as health-related quality of life, pain and wound recurrence.
Venous leg ulcers are a chronic health problem that cause considerable economic impact and affect quality of life for those who have them. Primary wound contact dressings are usually applied to ulcers beneath compression therapy to aid healing, promote comfort and control exudate. There are numerous dressing products available for venous leg ulcers and hydrogel is often prescribed for this condition; however, the evidence base to guide dressing choice is sparse.
To assess the effects of hydrogel wound dressings on the healing of venous leg ulcers in any care setting.
In May 2021, we searched the Cochrane Wounds Specialised Register, CENTRAL, Ovid MEDLINE, Ovid Embase and EBSCO CINAHL Plus. We also searched clinical trials registries for ongoing and unpublished studies, and scanned reference lists of relevant included studies, reviews, meta-analyses and health technology reports to identify additional studies. There were no restrictions with respect to language, date of publication or study setting.
We included randomised controlled trials (RCTs), either published or unpublished, that compared the effects of hydrogel dressing with other dressings on the healing of venous leg ulcers. We excluded trials evaluating hydrogel dressings impregnated with antimicrobial, antiseptic or analgesic agents as these interventions are evaluated in other Cochrane Reviews.
We used standard methodological procedures expected by Cochrane. We assessed the certainty of the evidence using the GRADE approach.
We included four RCTs (10 articles) in a qualitative analysis. Overall, 272 participants were randomised, in sample sizes ranging from 20 to 156 participants. The mean age of the included population in the trials ranged from 55 to 68 years, 37% were women based on studies that reported the sex of participants. The studies compared hydrogel dressings with the following: gauze and saline, alginate dressing, manuka honey and hydrocolloid. Two studies were multicentre and the others were single-centre trials. Length of treatment using hydrogel dressing was four weeks in three studies and two weeks in one study. The follow-up period was the same as the duration of treatment in three studies and in one study the follow-up for wound healing was at 12 weeks after four weeks of treatment. Overall risk of bias was high for all trials because at least one of the three key criteria (selection bias, detection bias and attrition bias) was at high risk.
Hydrogel compared with gauze and saline
It is uncertain whether there is a difference in complete wound healing (risk ratio (RR) 5.33, 95% confidence interval (CI) 1.73 to 16.42; 1 trial, 60 participants) or change in ulcer size (mean difference (MD) –1.50, 95% CI –1.86 to –1.14; 1 trial, 60 participants) between interventions because the certainty of the evidence is very low. Data reported from one trial were incomplete for time-to-ulcer healing.
Hydrogel compared with alginate dressing
It is uncertain whether there is a difference in change in ulcer size between hydrogel and alginate gel because the certainty of the evidence is very low (MD –41.80, 95% CI –63.95 to –19.65; 1 trial, 20 participants).
Hydrogel compared with manuka honey
It is uncertain whether there is a difference in complete wound healing (RR 0.75, 95% CI 0.46 to 1.21; 1 trial, 108 participants) or incidence of wound infection (RR 2.00, 95% CI 0.81 to 4.94; 1 trial, 108 participants) between interventions because the certainty of the evidence is very low.
Hydrogel compared with hydrocolloid
One study (84 participants) reported on change in ulcer size between hydrogel and hydrocolloid; however, further analysis was not possible because authors did not report standard errors or any other measurement of variance of a set of data from the means. Therefore, it is also uncertain whether there is a difference in change in ulcer size between hydrogel and hydrocolloid because the certainty of the evidence is very low.
No studies provided evidence for the outcomes: recurrence of ulcer, health-related quality of life, pain and costs.
Overall, independent of the comparison, the certainty of evidence is very low and downgraded twice due to risk of bias and once or twice due to imprecision for all comparisons and outcomes.