The electronic case report form represents the digital implementation of the data collection instrument used to capture protocol-specified information about each trial participant. Unlike paper CRFs that are completed by hand and subsequently entered into databases through double data entry processes, eCRFs allow direct data entry into validated electronic systems, eliminating transcription steps and enabling immediate data validation. Each eCRF is specifically designed to capture the data elements required by the study protocol, organized into forms corresponding to study visits and procedures.

The design of eCRFs requires careful attention to usability, data quality, and regulatory compliance. Forms must be intuitive for site personnel to complete, with logical organization and clear instructions for each field. Edit checks programmed into the forms identify potential errors through range checks, consistency checks, and conditional logic, prompting users when entered data appears incorrect or incomplete. The design must also support the statistical analysis plan by capturing data at the appropriate level of detail and in formats suitable for analysis, while maintaining traceability to source documents through appropriate labeling and documentation.

Regulatory agencies consider eCRFs to be source data when data are entered directly without prior recording in other documents, such as patient-reported outcomes captured through electronic patient diaries. In such cases, the eCRF must meet all requirements for source documents, including the ALCOA principles of attributability, legibility, contemporaneousness, originality, and accuracy. When the eCRF contains transcribed data, the original source documents must be maintained and available for verification. Regardless of source status, eCRF data must be maintained with appropriate controls and audit trails to ensure data integrity throughout the trial and beyond.