Background: Transparent and complete reporting of clinical trial information across registries and peer-reviewed publications is essential for reliable interpretation of clinical evidence. Previous studies have demonstrated discrepancies between trial registries and journal publications, but data specifically focusing on transfusion medicine trials remain limited. Objectives: To assess reporting completeness and consistency for key WHO Trial Registration Data Set (WHO TRDS) items and safety outcomes across the trial life cycle in transfusion medicine-related clinical trials. Methods: We conducted an observational study of clinical trials in transfusion medicine with available results registered in ClinicalTrials.gov between January 2011 and May 2019. Reporting of WHO TRDS items was evaluated at three predefined time points: initial registry entry, final registry update, and corresponding peer-reviewed journal publication. Changes and missing items were systematically assessed, and adverse event and mortality reporting were compared between registry records and journal publications. Results: A total of 67 eligible clinical trials were identified, of which 45 had corresponding peer-reviewed journal publications. At initial registration, several TRDS items were frequently missing, particularly timeline and outcome-related fields. Completeness improved substantially in the final registry updates but was not consistently maintained in journal publications, where incomplete or discordant reporting was common for enrolment and completion dates, eligibility criteria, and outcome definitions. Differences between final registry records and publications were observed in the majority of trials. Safety reporting also differed between sources: serious adverse events were reported at similar overall frequencies, but were more detailed in registry entries, whereas deaths were more frequently reported in publications and explicit reporting of zero adverse events was more common in the registry. Conclusions: Clinical trials in transfusion medicine show inconsistencies between registry records and corresponding journal publications across key methodological and safety reporting domains. These differences may limit transparency, reproducibility, and the reliability of evidence synthesis. Closer alignment between trial registries and scientific publications is needed to strengthen the trustworthiness of clinical information in transfusion medicine.

Background/Objectives: Transparent and complete reporting of clinical trial information across registries and peer-reviewed publications is essential for reliable interpretation of clinical evidence. Previous studies have demonstrated discrepancies between trial registries and journal publications, but data specifically focusing on transfusion medicine trials remain limited. To assess reporting completeness and consistency for key WHO Trial Registration Data Set (WHO TRDS) items and safety outcomes across the trial life cycle in transfusion medicine-related clinical trials. Methods: We conducted a retrospective observational study of completed transfusion medicine-related clinical trials registered in ClinicalTrials.gov, with registry results available between January 2009 and May 2019. Reporting of WHO TRDS items was evaluated at three predefined time points: initial registry entry, final registry update, and corresponding peer-reviewed journal publication. Changes and missing items were systematically assessed, and adverse event and mortality reporting were compared between registry records and journal publications. Results: A total of 67 eligible clinical trials were identified, of which 45 (67%) had corresponding peer-reviewed journal publications. At initial registration, several WHO TRDS items were frequently missing, particularly timeline- and outcome-related fields. Completeness improved substantially in final registry updates but remained inconsistent in journal publications, where discrepancies in eligibility criteria, outcome definitions, and study timelines were common. Differences between final registry updates and publications were observed in the majority of trials. Safety reporting also differed between sources: serious adverse events were reported in 31/45 (69%) registry entries and 26/45 (58%) publications, whereas deaths were more frequently reported in publications (27/45, 60%) than in registries (20/45, 44%). Conclusions: Clinical trials in transfusion medicine show inconsistencies between registry records and corresponding journal publications across key methodological and safety reporting domains. These differences may limit transparency, reproducibility, and the reliability of evidence synthesis. Closer alignment between trial registries and scientific publications is needed to strengthen the trustworthiness of clinical information in transfusion medicine.