Data collection on bowel movements is usually conducted using diaries completed by subject or other evaluator (e.g., caregiver). Fecal samples may also be taken by the subject or caregiver, or at hospitals or clinics.
Figure 5.1.1 represents three types of diary data collection:
- Subject Recall: At the visit, the subject is asked to recall from memory data such as the average number of stool episodes per day, or typical consistency of the stool over a set number of days prior to the visit. The subject is not required to keep detailed information on the number of episodes/type of consistency, but estimates these based on memory recall.
- End of Day Diary Completion: The subject is asked to complete a diary at the end of each day with the total number of stool episodes and typical consistency over the day.
- Each Episode Diary Completion: The subject is asked to complete a diary with the time of each stool episode and the typical consistency of that stool episode.
Figure 5.1.1 Types of Diary Collection
When providing diaries for a subject to complete, it is important to provide the subject with instructions on how and when to complete the diary; those instructions must be understood by all functions within the study team. Although this may differ from protocol to protocol, detailed, unambiguous instructions will help ensure that data are collected in a consistent format across all subjects. This may be particularly important when analyzing the data. Some diary completion instructions may be as simple as "Please record all bowel movements that occurred between 00:00 and 23:59 on this day." It may also be important to provide additional information on how subjects should record data if, for example, they retire to bed before or after midnight and then they have a bowel movement prior to or after midnight. Providing instructions on which diary day to record these episodes will help ensure that data are recorded consistently across all subjects.
Note: Some sponsors may use a standard instrument to collect information on the color/consistency of stool samples. SDTM modeling of these concepts should therefore follow the separate supplements for these scales. Please refer to Section 6, Questionnaires, Ratings, and Scales, for scales that have been identified for nutritional research.
The examples below show how subject recall, end of day, and each episode diary data may be collected using CDASH standards and represented in SDTM standards.