Ahn 1991.
| Methods | RCT | |
| Participants | Teaching Hospital, USA 48 patients Inclusion criteria: 29 patients with fresh surgical incisions (32 pairs of scars) 19 patients with established hypertrophic scars (23 scars) Exclusion criteria: not stated Sex: not stated Age: 12 to 44 years | |
| Interventions | silicone gel bandage worn for at least 12 hours/day (untreated adjacent or mirror image scar on same patient used as control) | |
| Outcomes | Length of follow‐up: measurements at 1, 2 and 6 months Clinical: scar elasticity, scar volume Complications: rash (5), ulcer (3), pruritus (1), discomfort (1) | |
| Notes | Elasticity quantitated serially with the use of an elastometer | |
| Risk of bias | ||
| Bias | Authors' judgement | Support for judgement |
| Random sequence generation (selection bias) | Unclear risk | Quote: “A test area of scar that was either 2 or 3 cm in length was arbitrarily selected so that an untreated control area of the same length and similar appearance was available from either the same or a mirror image anatomical site". Comment: no further information was given on how control and treatment areas were selected |
| Allocation concealment (selection bias) | Unclear risk | Comment: no information on allocation concealment was given in the study which we judged to be at unclear risk |
| Blinding of participants and personnel (performance bias) All outcomes | High risk | Quote: “Patients were instructed to wear a small silicone gel sheet on the test area scar for at least 12 hours a day. No treatment or dressing was used on the control scars” Comment: due to the nature of the treatment, we judged that participants and personnel could not be blinded |
| Blinding of outcome assessment (detection bias) All outcomes | Unclear risk | Quote: “Test and control scars were rated clinically by both the patient and the investigator at the completion of treatment.” Comment: no further information was given on blinding of outcome assessor which we judged to be at unclear risk of bias |
| Incomplete outcome data (attrition bias) All outcomes | High risk | Quote: “Thirty‐two scar pairs were originally entered into the study. . . . Ten patients (11 scar pairs did not complete one month of treatment and thus were nonassessable; most of these patients were men who were minimally concerned about the appearance of their truncal scars” Comment: the loss to follow‐up was greater than 20% therefore the study was judged to be at high risk of attrition bias |
| Selective reporting (reporting bias) | Low risk | Comment: the study protocol was not sought, however all measurements discussed in the methods are reported in the results and clinically meaningful outcomes presented. |
| Other bias | High risk | Quote: “The research was funded in part by a $10000 grant from Dow Corning Wright, Arlington, Tenn. The senior authors have received funds to conduct additional studies on silicone gel subsequent to this study from Dow Corning Wright. They do no own stock in Dow Corning Wright or its parent company. The authors certify that they have no affiliation with or financial involvement in any organisation with a direct financial interest in the subject matter or materials discussed in this article.” Comment: Dow Corning Wright was the brand of silicone gel used in the trial. We judged this to cause a high risk of bias. |