In Electronic Data Capture (EDC) systems, free text fields should be used only when a predefined list of acceptable responses cannot accommodate the full variability of input data --- most notably for Adverse Event (AE) verbatim terms.

According to the Good Clinical Data Management Practices (GCDMP, Chapter: CRF Design and Data Collection), AE verbatim terms are initially entered as free text by site staff to accurately capture the investigator's exact medical description of the event. These verbatim terms are later coded using standardized dictionaries such as MedDRA during medical coding, ensuring both flexibility and standardization in reporting.

Conversely, fields such as urine sedimentation rate (A), date of birth (C), and Body Mass Index (D) require structured numeric or date formats to enable validation, range checks, and consistency across datasets. Free text would compromise data integrity, accuracy, and validation efficiency for these structured data elements.

Reference (CCDM-Verified Sources):

SCDM Good Clinical Data Management Practices (GCDMP), Chapter: CRF Design and Data Collection, Section 4.3 -- Use of Free Text and Coded Fields

ICH E6 (R2) Good Clinical Practice, Section 5.5.3 -- Data Structure and Validation

MedDRA Introductory Guide, Section 2.3 -- Verbatim Entry and Coding Requirements