Diabetic foot ulcer photography study: a study within a trial to assess the reliability of two-dimensional (2D) photography for the assessment of ulcer healing in patients with diabetes-related foot ulcers-protocol paper

BACKGROUND: The primary endpoint in diabetes-related foot ulcer (DFU) trials is often time to healing, defined as complete re-epithelialisation with absence of drainage, requiring clinical expert assessment as the gold standard. Central blinded photograph review for confirmation of healing is increasingly being undertaken for internal validity. The Diabetic Foot Ulcer Photography study aims to determine the agreement between blinded independent review panel members for assessing ulcer healing status in patients with DFUs.

METHODS AND ANALYSIS: Photographs of ulcers clinically assessed as healed or not healed across 300 participants recruited to one of two randomised controlled trials (MIDFUT and CODIFI2), will be independently reviewed by a central blinded panel consisting of four clinicians with expertise in ulcer healing assessment. Staff at recruiting sites will take photographs using a standardised camera and protocol. Photographs will be reviewed at three levels of magnification: raw image, image standardised to a measurement scale included in the photograph and standardised image with magnification permitted. Reviewers will assess the healing status and their confidence level in making a healing judgement, with reasons reported for a low confidence rating. Analysis at each level of magnification will estimate inter- and intra-rater reliability on the assessments of healing of photographs with the clinical assessment (primary) and confidence rating using multivariable logistic mixed models. Analysis of the learning curve for the assessment of healing and confidence rating will use exponential and two-phase models.

ETHICS AND DISSEMINATION: Ethics approval has been granted by the National Research Ethics Service Committees (MIDFUT 17/YH/0055; CODIFI2 18-WS-0235). All participants will provide a written informed consent for photography before recruited onto the respective study. Photographs will be transferred to the trials' coordinating centre via a secure file transfer service and saved in a restricted access folder on a secure server. Results will be disseminated via publications in scientific journals and conference presentations.

TRIAL REGISTRATION NUMBER: MIDFUT (ISRCTN64926597) and CODIFI2 (ISRCTN74929588).