Regulatory agencies, such as the U.S. Food and Drug Administration (FDA), mandate specific electronic submission standards to ensure the integrity, security, and consistent review of clinical trial documentation. The electronic Common Technical Document (eCTD) is the standard format for submissions. Within the eCTD structure, individual subject Case Report Forms (CRFs) must be submitted as Portable Document Format (.pdf) files. This format is required because it preserves the original document's layout, content, and signatures in a non-editable, universally viewable manner, which is critical for regulatory review and archival purposes. The PDF format ensures that the submitted CRF is a true and unalterable copy of the original record.

B. Rich Text Format (.rtf): This is an editable text format that does not preserve the fixed layout or guarantee the document's integrity required for a final regulatory submission.

C. Microsoft Word (.docx): This is a proprietary and editable word-processing format, making it unsuitable for submitting a final, unchangeable official record like a CRF.

D. Statistical Analysis System (.sas): This format is used for submitting clinical trial datasets (e.g., SDTM, ADaM), not for the visual representation of the completed CRF document itself.

1. U.S. Food and Drug Administration (FDA). eCTD Technical Conformance Guide: Technical Specifications Document. July 2022. In Section 4.1, "File Format," the guide specifies, "All documents must be submitted as PDF files..." This requirement applies to documents like CRFs provided in Module 5 (Clinical Study Reports) of the eCTD.

2. Society for Clinical Data Management (SCDM). Good Clinical Data Management Practices (GCDMP). April 2023. Chapter 16, "Data Archiving and Submission," discusses the preparation of data and documentation for regulatory submission, aligning with agency requirements for submission-ready, non-editable formats like PDF for case report forms.

3. Mitchel, J., et al. (2008). The Role of the Clinical Data Manager in an Electronic Submission. Drug Information Journal, 42(5), 447-455. This article details the process of preparing for an electronic submission, stating, "Case report forms (CRFs) for all deaths, other serious adverse events, and discontinuations due to adverse events are provided as PDF files..." (p. 451). https://doi.org/10.1177/009286150804200507