A Retrospective Observational Study to Evaluate the Causes of Screen Failure in a Pilot Study on Diabetic Foot Ulcers

Objective: Screening in clinical trials ensures participant eligibility, supporting safety and scientific validity. The CONsolidated Standards of Reporting Trials flowchart reports eligibility assessments but often omits detailed exclusion reasons. Understanding screen failures can help refine eligibility criteria, improve recruitment, and guide future trial designs. A pilot study on topical phenytoin for diabetic foot ulcers at our institute had a high screen failure rate. This study aimed to identify the reasons behind those failures.Methods: This retrospective observational study was conducted at a tertiary care hospital. Following ethics approval, demographic and clinical data, including lab values and Ankle-Brachial Pressure Index (ABPI), were extracted from screening records. Screen failure frequencies were analyzed and their causes categorized to identify common patterns.Results: Of 42 participants screened in the original study, 14 (33%) were excluded. The leading reason was elevated glycated haemoglobin (HbA1c) (50%, n=7), followed by high ABPI (29%, n=4) and low protein levels (14%, n=2). Categorization of causes of screen failures showed uncontrolled type-2 diabetes mellitus (44%, n=7) as the primary cause, followed by diabetes-related complications (31%, n=5) and comorbidities (19%, n=3).Conclusion: Elevated HbA1c was the most common reason for screen failure followed by high ABPI, highlighting the challenges of designing strict criteria in diabetic foot ulcer trials. Adjusting HbA1c thresholds while ensuring safety may enhance recruitment without compromising study integrity. Future studies should consider more flexible criteria to improve feasibility and enrollment.