Cullen 2012.

Methods	RCT Setting: not reported Country: UK Duration of follow‐up: 4 weeks Treatments: collagen/ORC/silver treatment and collagen/ORC (randomised); and compression
Participants	64 participants with VLUs Age: not reported Sex: not reported Stage of ulcer: not reported Ulcer duration: not reported Ulcer size at baseline: not reported Wound infection: not reported Number of wounds: 64 (inferred) Inclusion criteria: VLUs (no further details) Exclusion criteria: not reported
Prognostic factors	Human neutrophil elastase (dichotomous data); 'elastase activity.' Measurement method fluorogenic substrate assay: cut‐off point based on Serena 2011 (> 25 mU/110 µL) Time of measurement: baseline and then every 2 weeks for 4 weeks Wound fluid sampling method: not stated
Notes	Conference abstract. Authors worked for Systagenix and were involved in developing a diagnostic test based on elevated protease levels.
Risk of bias
Bias	Authors' judgement	Support for judgement
Selection bias	High risk	< 2 months' follow‐up (only 4 weeks). Participants from a single clinic implied. No details
Attrition bias	Unclear risk	Moderate: 8/64 (12.5%) participants missing due to deviations from protocol. Unclear whether missing data in people with elevated protease
Prognostic factor measurement	Unclear risk	Moderate: cut point validity depended on reliability of Serena 2011 study
Outcome measurement	High risk	30% reduction in size. No adjustment for baseline size mentioned
Adjustment factors	High risk	None of the key confounders taken into account in the design or analysis
Analysis and reporting	High risk	Likely interaction with treatment that was designed to be protease modulating. No account in analysis
Overall risk of bias	High risk