Personalized Care Pathways for Bowel Symptoms in Rectal Cancer patients_development of E-diary

Primary outcomes

1. Selection of items for the newly developed bowel diary

   Time frame: 12 months

   The selection of items for a comprehensive bowel diary in patients with rectal cancer is based on a literature review, a patient focus group and an international Delphi survey. The patient focus group is recorded using an audio and video recording. This recording is transcribed verbatim by the researcher into a Word document. The transcription will be analyzed using NVIVO 9 software. In this Delphi survey, a multidisciplinary group of experts will score each item of the long list on a 1-9-point Likert scale from 'Not relevant' (1) to 'Essential' (9) for inclusion in the bowel diary. Finally, a patient consultation meeting and a consensus meeting will be held for the participants who completed the Delphi survey.

2. Assessment of content validity of the newly developed bowel diary in a post-Delphi patient focus group consisting of 8-12 participants

   Time frame: 12 months

   Content validation of the newly developed bowel diary will be tested during interview in the post-Delphi patient focus group. This focus group is recorded using an audio and video recording. This recording are transcribed verbatim by the researcher into a Word document. The transcription will be analyzed using NVIVO 9 software.

3. The usability of the newly developed e-diary, assessed with the System Usability Scale (SUS) in patients after rectal surgery for rectal cancer

   Time frame: 12 months

   The participants will be asked to use a newly developed electronic bowel diary for 7 consecutive days. This bowel diary will be available on the smartphone in the form of an application. After 7 days, the usability of this e-diary will be assessed with the System Usability Scale (SUS). The SUS is a questionnaire consisting of 10 items, utilizing a 5-point Likert scale to measure users' perceived satisfaction with the system. It includes two subscales focusing on usability and learnability. Scores on the SUS range from 0 to 100, with no direct correlation to percentiles (i.e., a score of 60 does not signify a usability level of 60%). Instead, a score of 70 points or higher is commonly employed as an initial threshold indicating acceptable usability. This benchmark is derived from the overall mean of more than 200 studies covering various systems and products.

4. The usability of the newly developed e-diary will be evaluated through conversations with patients who have undergone rectal surgery for rectal cancer, after these patients have used the e-diary for seven consecutive days

   Time frame: 12 months

   Participants will be instructed to use a newly developed electronic bowel diary via a smartphone app for seven consecutive days. The research will then conduct conversations with the participants covering aspects such as complexity, the need for additional support, application coherence, user-friendliness, pre-existing knowledge requirements, and suggestions for improvement. Audio and video recordings of these conversations will be transferred to the researcher's computer and subsequently transcribed into a Word document. The transcriptions will be analyzed using NVIVO 9 software.

5. Construct validity of the newly developed bowel e-diary: Known groups method

   Time frame: 12 months

   Patients will be divided into two groups based on their LARS score: no/minor LARS and major LARS. Over a 7-day period, patients will be asked to complete the bowel diary, which will then be examined to determine if there is a meaningful difference between the two groups. The Mann-Whitney U-test will be used to assess whether the difference is significant, and the C-index will be calculated to evaluate how well the test distinguishes between the groups. A C-index of 0.65 or higher would indicate that the test is effective at differentiating between the groups.

6. Construct validity of the newly developed bowel e-diary: Convergent and divergent validity

   Time frame: 12 months

   The bowel diary will be completed by patients over a 7-day period, while the questionnaires (such as LARS, MSKCC-BFI, COREFO, PAC-SYM, QLQ-C30) will be filled out on day 7.

   The correlation between the bowel diary and the questionnaires (such as LARS, MSKCC-BFI, COREFO, PAC-SYM, QLQ-C30) will be calculated. The correlation will be performed across the entire set of questionnaires and bowel diary items, while pairwise correlations at the subscale level will analyze the relationship between related factors.

7. Test-retest reliability of the newly developed bowel e-diary

   Time frame: 12 months

   To investigate the test-retest reliability of the newly developed bowel e-diary, patients will have to fill out the bowel diary application twice, each time for a continuous period of 7 days, during a period when the disorder and treatment do not change (i.e., after the end of adjuvant treatment and/or after closure of an eventual temporary postoperative ileostomy).

8. Responsiveness of the newly developed bowel e-diary in patients after rectal surgery for rectal cancer. The newly validated e-diary is the primary outcome.

   Time frame: 12 months

   To evaluate the responsiveness of the new bowel diary, patients will complete the diary for 14 consecutive days. The first 7 days (day 1-7) will be compared with the following 7 days (day 7-14). Internal responsiveness will be calculated using the Standardized Response Mean (SRM) for the bowel diary. External responsiveness will be assessed by calculating the SRM for both the bowel diary and the LARS score and MSKCC-BFI questionnaires.

9. Explorative analysis of bowel symptoms in Watch and Wait

   Time frame: 12 months

   To exploratively analyse the type and severity of bowel symptoms in patients managed with a Watch and Wait strategy, and to compare these symptoms with those reported by patients who underwent TME/PME surgery.