Silicone gel sheeting for treating keloid scars

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 methods: 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. 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.