What are the benefits and risks of silicone gel sheeting for treating keloid scars?

Key messages

We are uncertain whether silicone gel sheeting improves a scar's appearance more than: 

- no treatment; 

- treatment with a dressing similar to silicone gel sheeting that does not contain silicone;

- injections of triamcinolone acetonide (a medication) directly into a lesion or below the skin.

We are uncertain about the effect of silicone gel sheeting on pain compared with no treatment. 

We do not know if silicone gel sheeting has an effect on pain compared with non-silicone gel sheeting or intralesional injections of triamcinolone acetonide.

What are keloid scars?

A scar is a mark left on the skin after a wound or injury has healed. Sometimes scars can develop abnormally, forming keloid scars which are raised and unsightly and these can affect people physically and emotionally. Keloid scars often occur after minor injuries and can spread to the skin surrounding the original wound. Keloid scars are difficult to treat and can affect both sexes and occur at any age. 

How are keloid scars treated?

Silicone gel sheeting is a soft and flexible wound dressing containing an elastic form of silicone. It has a soft, rubbery texture and can be easily attached to the skin. Silicone gel sheeting is thought to be an optimal option in the treatment of keloid scars. It can be used on healing skin to help soften and flatten a keloid scar.

What did we want to find out?

In this Cochrane Review, we wanted to find out what the benefits and risks of treating keloid scars with silicone gel sheeting are.

What did we do? 

We searched for studies that investigated using silicone gel sheeting to treat keloid scars. We searched for randomised controlled trials only, in which the treatment each person receives is chosen at random. These studies give the most reliable evidence about the effects of a treatment.

What did we find? 

We found two studies with a total of 36 participants (85 scars) (33 participants (76 scars) completed the study). The participants had keloid scars caused by surgery, infected wounds or trauma. The studies compared the effects of silicone gel sheeting with: 

- no treatment;

- treatment with a dressing similar to silicone gel sheeting that did not contain silicone;

- injections of triamcinolone acetonide (a medication) directly into a lesion or below the skin.

One study was conducted in Brazil and another study was conducted in Singapore. They lasted for different lengths of time: three months and four and a half months.

Both studies reported assessments of scars by healthcare professionals but no data were reported in a way that was usable for this review. No studies reported useful results for the person's own assessment of their scar after treatment. Both studies also reported assessments of pain but no data were reported in a way that was usable for this review.

No studies reported useful results for people's well-being (quality of life); whether people stayed on the treatment (adherence); whether the treatments had any unwanted effects; or whether the treatments were cost-effective (the benefits of treatment outweighed any extra costs).

Main results

We are uncertain whether silicone gel sheeting improves a scar's appearance more than: no treatment; treatment with non-silicone gel sheeting; or intralesional injections of triamcinolone acetonide.

We are uncertain about the effect of silicone gel sheeting on pain compared with no treatment. We do not know if silicone gel sheeting has an effect on pain compared with non-silicone gel sheeting or intralesional injections of triamcinolone acetonide.

Conclusions

We are uncertain whether the use of silicone gel sheeting compared with no treatment, treatment with non-silicone gel sheeting or intralesional injections of triamcinolone acetonide makes any difference in the treatment of keloid scars. 

What are the limitations of the evidence?

We are not confident in the evidence because it comes from very few studies with small numbers of people and poorly reported results, so we are not sure how reliable the results are. Our conclusions would be likely to change if results from further studies become available.

How up-to-date is this evidence?

This review includes evidence published up to 15 December 2021.

Authors' conclusions: 

There is currently a lack of RCT evidence about the clinical effectiveness of SGS in the treatment of keloid scars. From the two studies identified, there is insufficient evidence to demonstrate whether the use of SGS compared with no treatment, non-SGS, or intralesional injections of triamcinolone acetonide makes any difference in the treatment of keloid scars. Evidence from the included studies is of very low certainty, mainly driven by the risk of bias, indirectness, and imprecision due to small sample size. Further well-designed studies that have good reporting methodologies and address important clinical, quality of life and economic outcomes are required to reduce uncertainty around decision-making in the use of SGS to treat keloid scars.

Read the full abstract...
Background: 

Keloid scarring is one of the most common types of pathological scarring. Keloid scars that fail to heal can affect a person's physical and psychological function by causing pain, pruritus, contractures, and cosmetic disfigurement. Silicone gel sheeting (SGS) is made from medical-grade silicone reinforced with a silicone membrane backing and is one of the most commonly used treatments for keloid scars. However, there is no up-to-date systematic review assessing the effectiveness of SGS for keloid scars. A clear and rigorous review of current evidence is required to guide clinicians, healthcare managers and people with keloid scarring.

Objectives: 

To assess the effectiveness of silicone gel sheeting for the treatment of keloid scars compared with standard care or other therapies.

Search strategy: 

We used standard, extensive Cochrane search methods. The latest search date was December 2021.

Selection criteria: 

We included randomised controlled trials (RCTs) that recruited people with any keloid scars and assessed the effectiveness of SGS.

Data collection and analysis: 

Two review authors independently performed study selection, risk of bias assessment, data extraction and GRADE assessment of the certainty of evidence. We resolved initial disagreements by discussion, or by consulting a third review author when necessary.

Main results: 

Two studies met the inclusion criteria. Study sample sizes were 16 and 20 participants. The trials were clinically heterogeneous with differences in causes for scarring (e.g. surgery, infected wounds, and trauma), site (e.g. chest and back), and ages of scars. The duration of follow-up was three and four and a half months. The included studies reported three comparisons; SGS compared with no treatment, SGS compared with non-silicone gel sheeting (a dressing similar to SGS but which does not contain silicone), and SGS compared with intralesional injections of triamcinolone acetonide. One trial had a split-body design and one trial had an unclear design (resulting in a mix of paired and clustered data).

The included studies reported limited outcome data for the primary review outcome of scar severity measured by health professionals and no data were reported for severity of scar measured by patients or adverse events. For secondary outcomes some data on pain were reported, but health-related quality of life and cost-effectiveness were not reported. Both trials had suboptimal outcome reporting, thus many domains in the risk of bias were assessed as unclear. All evidence was rated as being very low-certainty, mainly due to risk of bias, indirectness, and imprecision. 

SGS compared with no treatment

Two studies with 33 participants (76 scars) reported the severity of scar assessed by health professionals, and we are uncertain about the effect of SGS on scar severity compared with no treatment (very low-certainty evidence, downgraded once for risk of bias, once for inconsistency, once for indirectness, and once for imprecision). We are uncertain about the effect of SGS on pain compared with no treatment (21 participants with 40 scars; very low-certainty evidence, downgraded once for risk of bias, once for inconsistency, once for indirectness, and once for imprecision). No data were reported for other outcomes including scar severity assessed by patients, adverse events, adherence to treatment, health-related quality of life and cost-effectiveness.

SGS compared with non-SGS

One study with 16 participants (25 scars) was included in this comparison. We are uncertain about the effect of SGS on scar severity assessed by health professionals compared with non-SGS (very low-certainty evidence, downgraded once for risk of bias, once for indirectness, and once for imprecision). We are also uncertain about the effect of SGS on pain compared with non-SGS (very low-certainty evidence, downgraded once for risk of bias, once for indirectness, and once for imprecision). No data were reported for other outcomes including scar severity assessed by patients, adverse events, adherence to treatment, health-related quality of life and cost-effectiveness.

SGS compared with intralesional injections of triamcinolone acetonide

One study with 17 participants (51 scars) reported scar severity assessed by health professionals, and we are uncertain about the effect of SGS on scar severity compared with intralesional injections of triamcinolone acetonide (very low-certainty evidence, downgraded once for risk of bias, once for indirectness, and once for imprecision). This study also reported pain assessed by health professionals among 5 participants (15 scars) and we are uncertain about the effect of SGS on pain compared with intralesional injections of triamcinolone acetonide (very low-certainty evidence, downgraded once for risk of bias, once for indirectness, and twice for imprecision). No data were reported for other outcomes including scar severity assessed by patients, adverse events, adherence to treatment, health-related quality of life and cost-effectiveness.