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Comparison of Silicone Sheets and Paper Tape for the Management of Postoperative Scars

A Randomized Comparative Study

Lin, Ying-Sheng MD, MPH; Ting, Pei-San MSc; Hsu, Kuei-Chang MD

Author Information
Advances in Skin & Wound Care: June 2020 - Volume 33 - Issue 6 - p 1-6
doi: 10.1097/01.ASW.0000661932.67974.7d
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Abstract

INTRODUCTION

Surgical or accidental skin injury is unavoidable. Some types of wounds can heal uneventfully, whereas others, such as surgical wounds, may heal with undesirable scars. Silicone sheets have been universally accepted as the criterion standard in scar management,1 but they are difficult to apply to the head and neck area or across joints. Paper tape is a much cheaper and easy-to-apply dressing and has been proven to prevent hypertrophic scarring.2 In this study, researchers conducted a head-to-head comparison to evaluate the effectiveness of silicone sheets and paper tape in the prevention of postoperative cesarean section scars. Researchers chose cesarean section scars because they tend to be noticeable on those with an East Asian skin tone, and female patients are often more willing to receive antiscar treatments. In comparison, for example, sternotomy patients are usually male and often less willing to receive antiscar treatments.

METHODS

This randomized comparative study was approved by the institutional review board of the authors’ hospital (ID: VGHKS97-051) and registered at ClinicalTrials.gov (NCT00849004), and all patients provided written informed consent to participate. It was conducted at a tertiary medical center in southern Taiwan. Investigators recruited patients undergoing horizontal cesarean section who were referred from the obstetric clinic in the same hospital.

Exclusion criteria were wound infection, long-term use of system steroids, use of herbal agents, allergy to silicone, or unwillingness to adhere to study protocol (Figure 1). Patient ability and willingness to participate in this study was assessed during the initial consult, and researchers demonstrated how to apply the dressing. To ensure patient adherence to the interventions during the trial period, patients who had difficulty applying the dressings per the protocol were excluded. Researchers collected demographic data including age, race, diabetes diagnosis, smoking status, and history of hypertrophic or keloid scarring.

Figure 1
Figure 1:
FLOW DIAGRAM

After surgery, each participant’s wound was divided into two halves: right and left. Research assistants randomly assigned an allocation ratio of 1 to 1. The randomization was performed using a computerized random sequence generator with a block of four. A silicone sheet (CICA-CARE; Smith & Nephew, Fort Worth, Texas) was applied to one side, and paper tape (Steri-Strip; 3M, Minneapolis, Minnesota) was applied to the other side based on this randomization. The study was not blinded because patients or providers would know which dressing was applied to which side based on the dressing’s appearance and texture. The use of each dressing was started 1 week postoperatively and persisted for 3 months. Each dressing was applied for 24 hours a day except during showering, and new dressings were applied after each shower and each evaluation.

Investigators assessed the surgical scars at 1, 3, 6, and 12 months postoperation. At 1 and 6 months postsurgery, a telephone inquiry was conducted, whereas an in-person assessment was performed at the 3- and 12-month follow-up visits. During the in-person follow-up visits, scars were evaluated and scored by three research assistants based on the Vancouver Scar Scale (VSS). At each of the four follow-up time points, patient-reported evaluations were provided based on the visual analog scale (VAS) in terms of itch, pain, and scar appearance for each scar half.

Stata 9.1 (StataCorp Inc, College Station, Texas) was used for statistical analysis. An estimated sample size calculation was performed with the following assumptions: power, 0.8; α, 5%; sampling ratio, 1:1; SD, 3; and effect size, 2. The estimated sample size was 36. A paired t test was used to compare the differences in mean VAS scores at different time points. A χ2 test was used to compare the differences in each aspect of the VSS. Researchers used Fisher exact test to analyze the subgroup with a history of keloids or hypertrophic scarring. P < .05 was considered statistically significant.

RESULTS

A total of 47 eligible patients were recruited from October 25, 2008 to October 24, 2013. Table 1 presents the baseline demographic characteristics. All patients were Asians. The average age was 34.47 ± 6.42 years. Only one patient (2%) had a history of smoking. Seven patients had a history of hypertrophic or keloid scars.

Table 1
Table 1:
BASELINE DEMOGRAPHIC CHARACTERISTICS

In terms of VSS score, there was no statistically significant difference between the two groups with respect to pliability, height, vascularity, and pigmentation at 3 (Table 2) and 12 (Table 3) months’ follow-up (Figure 2).

Table 2
Table 2:
VANCOUVER SCAR SCALE (VSS) COMPARISON BETWEEN GROUPS AT 3-MONTH FOLLOW-UP
Table 3
Table 3:
VANCOUVER SCAR SCALE (VSS) COMPARISON BETWEEN GROUPS AT 12-MONTH FOLLOW-UP
Figure 2
Figure 2:
COMPARISONS BETWEEN GROUPS FOR THE VANCOUVER SCAR SCALEA, Pliability; B, height; C, vascularity; D, pigmentation.

In terms of VAS scores, the silicone sheet group had significantly better scar appearance than the paper tape group at 6 (6.81 ± 1.47 vs 6.19 ± 1.62, P = .03) and 12 (6.88 ± 2.01 vs 6.2 ± 2.08, P = .04) months’ follow-up. However, there was no statistically significant difference between the two groups with respect to itch and pain at any of the follow-up time points (Figure 3).

Figure 3
Figure 3:
COMPARISONS BETWEEN GROUPS FOR THE VISUAL ANALOG SCALEA, Itch; B, pain; C, scar appearance.

In the subgroup with a history of keloids or hypertrophic scarring, no statistically significant difference was noted at any time point in terms of VSS or VAS score (Figures 2 and 3). See Figure 4 for an example of scar appearance at 3 and 12 months.

Figure 4
Figure 4:
SCAR APPEARANCEA, Postoperative 3-month cesarean section scar; B, postoperative 1-year cesarean section scar. For each scar, the left half (from the patient’s perspective) was treated with paper tape, and the right half was treated with the silicone sheet.Photographs published with patient consent.

DISCUSSION

Scar formation after injury or surgery varies greatly in different parts of the body and in different ethnic groups. It can be as high as 60% in median sternotomy wounds.3 In other parts of the body with less skin tension, scarring may be less likely. However, scars occurring in visible areas such as the face or the forelimbs or recurrently pruritic scars affect patient quality of life. To tackle these problems, various treatment modalities have been developed such as corticosteroid injections,4,5 silicone sheets,6–8 silicone gels,9–13 paper tape,2 laser therapy,14–17 surgery,18 pressure therapy,19–23 radiotherapy,24,25 and cryotherapy.26,27

Silicone sheet application was first found to be an effective treatment for burn scar management in 1983.28 Even though several subsequent clinical trials have validated the efficacy of silicone sheets for preventing scars,29–32 its exact functional mechanism remains unknown. Further, a recent evidence-based review33 concluded that silicone sheets are only somewhat effective in the prevention of scarring among high-risk individuals. Nevertheless, silicone-based dressings are still considered the first-line option for scar management. However, silicone is not the only method for scar prevention.

Paper tape is one of the simplest interventions that surgeons use for wound closure. Early medical tapes were far from ideal; they blocked perspiration, irritated the skin, and were painful to remove. In 1962, 3M introduced Steri-Strip Skin closures, which were quickly embraced by surgeons.34 Later, evidence emerged on the effect of paper tape in the prevention of keloids and hypertrophic scars.2 Because of its low cost and high accessibility, these authors aimed to compare paper tape’s effectiveness with that of relatively expensive silicone sheets.

This study revealed no statistically significant difference in VSS score at 3 (Table 2) and 12 months (Table 3). However, these data revealed statistically significant differences in terms of scar appearance at 6 and 12 months’ follow-up based on the VAS score (Figure 3). That said, the differences in the scores were less than one point on a scale of 1 to 10 and are therefore not clinically meaningful.

The analysis of the subgroup with a history of keloid or hypertrophic scarring showed no statistically significant differences during the follow-up period, which might be attributable to small sample size (n = 7). Further study could focus on this specific group of patients to address this issue.

Ethnicity is a widely known factor in scar formation. White individuals are less prone to scar formation. Therefore, further study could be conducted in a multiethnic setting to investigate this issue.

Strengths and Limitations

In this study, researchers applied both dressings to each patient. The benefit of such a design is that it may eliminate confounding factors among individuals by having each patient serve as her own comparison. Further, at each follow-up time point, there was a varying percentage of patients lost to follow-up; however, every patient who was lost to follow-up contributed equally to the missing data for both the dressings, reducing the bias between groups.

The initial sample size estimation calculation was based on an SD of three. However, most SDs in the data set were less than 3. The decrease in SD increased the statistical power, compensating the power loss from dropouts. Therefore, despite a certain portion of patients lost to follow-up at each time point, the minimal detectable difference was still less than 3 on a scale of 1 to 10. In other words, the data at each time point were still sufficiently powered to detect any clinically meaningful difference and thus should not affect the conclusions. However, further study with a larger sample size is still necessary to elucidate this analysis.

Scar maturation takes approximately 6 months to 1 year,35 corresponding to this study’s 12-month follow-up period. A longer follow-up period may have yielded better results but also could lead to higher loss to follow-up. Another limitation of this study was the absence of blinding; patients were aware of the type of dressing applied to each side of their wound. Further, this study lacked a control group. The ideal control group should involve no treatment at all; however, this would likely be unethical.

According to previous studies, various postoperative skin conditions such as scarring36 and certain cutaneous disorders such as acne or atopic eczema37 are related to menstrual cycles that contribute to hormonal fluctuation. Therefore, follow-up at different phases of the menstrual cycle might affect scar presentation. In addition, for postpartum women, the return of the normal menstrual cycle is related to the choice between breast-feeding and formula-feeding. This information was not tracked in this study; again, because each patient served as her own control, the impact from this potential confounding factor is likely limited.

Finally, although the VSS assessment is based on clearly defined and objective criteria, interrater differences are possible. In this study, three research assistants participated in the assessment of VSS. Different raters may have given different judgments for similar scars, which might impose some potential error on the results of this study. However, because this study was based on head-to-head comparisons between two dressings on the same patient, unless the research assistants held different judgment standards for different dressings, the results were likely minimally affected by this factor.

CONCLUSIONS

Statistically speaking, silicone sheets were not different from paper tape in any aspect of the VSS at 3 and 12 months’ follow-up, but were superior to paper tape in terms of scar appearance at the 6- and 12-month follow-ups. Despite this, study authors think the differences are too small to be clinically meaningful for most patients. Accordingly, both dressings should be judged by patients and clinicians based on individual situation and preference.

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Keywords:

cesarean section; paper tape; postoperative scar; silicone sheet; Vancouver Scar Scale; visual analog scale

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