Grotewohl 1994.

Study characteristics
Methods	Design: multicentre RCT Country: Germany Setting: not reported Sample size calculation: not reported Ethical approval: not reported Informed consent: was obtained
Participants	Total sample: 84 participants with ulcera crurum Inclusion criteria: none specified Exclusion criteria: none specified Numbers randomised Group 1 (hydrogel dressing): 39 participants with 41 ulcers Group 2 (hydrocolloid dressing): 24 participants, 24 ulcers (1 participant with a double‐sided ulcer was treated with both products at once) ABPI: not reported Unit of analysis: ulcer Baseline ulcer size cm² (mean) (before treatment) Group 1 (hydrogel dressing): 10.1 Group 2 (hydrocolloid dressing): 6.3 Ulcer infection: not reported Data collected: ulcer dimension by planimetry Comments: the study started with 84 participants, but only 62 participants were followed for 28 days of the study. There was no justification for the dropouts. The trial author reported that 3 participants from the hydrogel group had double‐sided ulcers; 1 of these participants was treated with hydrogel and hydrocolloid at once
Interventions	Group 1: hydrogel dressing (Opragel, Lohmann) Group 2: hydrocolloid dressing (proprietary name not reported, manufacturer not reported) *All participants were subjected to compression therapy Description of compression therapy: not reported Length of treatment: 4 weeks Follow‐up: 4 weeks
Outcomes	Complete wound healing: reported that some ulcers were completely healed after 28 days and several participants after 14 days (no numbers reported) Incidence of wound infection: not reported Change in ulcer size: reported, planimetry used to measure the wound at day 14 and 28 of treatment Group 1 (hydrogel dressing): reduction of 44.6% at day 28 Group 2 (hydrocolloid dressing): reduction of 33.3% at day 28 Time to ulcer healing: not reported Recurrence of ulcer: not reported Health‐related quality of life: not reported Pain: not reported Costs: not reported
Notes	No details of the number of ulcers healed at end of trial were provided. Exclusions post‐randomisation: 22 exclusions, no reason provided for withdrawal and no details provided regarding number of withdrawals per group. The trial author reported no observed cases of irritation or allergic reactions with the use of dressings No details explaining the imbalance in allocation between study groups Group 1: "4 ulcers did not demonstrate signs of healing". Group 2: "3 ulcers did not demonstrate signs of healing". Funding: not described.
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Unclear risk	Quote: "The assignment was carried out to the principle of random selection". Comment: method of generating the random sequence was not reported.
Allocation concealment (selection bias)	Unclear risk	Comment: no mention of allocation concealment in study report#.
Blinding of participants and personnel (performance bias) All outcomes	Unclear risk	Comment: no mention of blinding in study report.
Blinding of outcome assessment (detection bias) All outcomes	Unclear risk	Comment: no mention of blinding in study report.
Incomplete outcome data (attrition bias) All outcomes	High risk	Comment: authors did not report withdrawals per groups (22/84 participants were excluded) and data were not fully reported. Trial authors only presented percentage of healing without present SD, standard error, CI or any other statistical analysis, precluding review authors to perform further analysis of data. Authors described that "In some cases the ulcers were completely healed after 28 days …" but did not provide number of healed ulcers per group.
Selective reporting (reporting bias)	Low risk	Comment: all trial outcomes described in the methods section of the report were included in the results section. Unable to obtain RCT protocol (no response from email sent to trial author).
Other bias	High risk	Comment: study showed inconsistency of data based on the number of participants with multiple ulcers and also imbalance with baseline ulcer surface area.