Patient-Reported Outcomes Following Loose Seton Material Replacement in Complex Anal Fistula

Within-participant change in disease-specific quality of life from baseline with the polypropylene loose seton in situ to 12 weeks after replacement with the braided polyester loose seton, assessed using the 14-item Quality of Life in Patients with Anal Fistula Questionnaire (QoLAF-Q). The total score ranges from 14 to 70, with higher scores indicating a greater negative impact of anal fistula on quality of life and therefore a worse outcome. The primary outcome will be calculated as the within-participant change in total QoLAF-Q score between baseline and 12 weeks after seton replacement.

Within-participant change in perianal pain from baseline with the polypropylene loose seton in situ to 4 and 12 weeks after replacement with the braided polyester loose seton, assessed using the 10-cm Visual Analogue Scale (VAS). The scale ranges from 0 to 10, where 0 indicates no pain and 10 indicates the worst imaginable pain. Higher scores indicate greater pain severity and therefore a worse outcome.

Within-participant change in anal continence from baseline with the polypropylene loose seton in situ to 4 and 12 weeks after replacement with the braided polyester loose seton, assessed using the Wexner Fecal Incontinence Score. The total score ranges from 0 to 20, where 0 indicates perfect continence and 20 indicates complete fecal incontinence. Higher scores indicate more severe fecal incontinence and therefore a worse outcome.

Within-participant change in overall comfort associated with the loose seton from baseline with the polypropylene loose seton in situ to 4 and 12 weeks after replacement with the braided polyester loose seton, assessed using an investigator-defined 5-point Patient Comfort Rating Scale. Scores range from 1 to 5: 1, very uncomfortable; 2, uncomfortable; 3, neither uncomfortable nor comfortable; 4, comfortable; and 5, very comfortable. Higher scores indicate greater patient comfort and therefore a better outcome.

Within-participant change in overall satisfaction with the loose seton from baseline with the polypropylene loose seton in situ to 4 and 12 weeks after replacement with the braided polyester loose seton, assessed using an investigator-defined 5-point Patient Satisfaction Rating Scale. Scores range from 1 to 5: 1, very dissatisfied; 2, dissatisfied; 3, neither dissatisfied nor satisfied; 4, satisfied; and 5, very satisfied. Higher scores indicate greater patient satisfaction and therefore a better outcome.

Participant-reported preference after experiencing both the polypropylene and braided polyester loose setons will be assessed using an investigator-defined single-item questionnaire: "Considering your overall experience, which loose seton material would you prefer?" Response options will be: (1) polypropylene loose seton, (2) braided polyester loose seton, and (3) no preference. Results will be reported as the number and percentage of participants selecting each response category. This is a categorical outcome; therefore, no minimum or maximum score or direction of scoring applies.

Cumulative analgesic consumption after replacement of the polypropylene loose seton with the braided polyester loose seton will be assessed using a participant-reported medication diary. Participants will record the name of each analgesic medication, the dose taken, and the date of administration. The outcome will be expressed as the total number of analgesic doses taken by each participant during the 12-week follow-up period. The minimum possible value is 0 doses, with no predefined maximum. Higher values indicate greater analgesic requirement and therefore a worse outcome.

Number and proportion of participants experiencing postoperative complications during follow-up, including local infection and premature seton loss.

The occurrence of any unplanned treatment-related healthcare utilization or reintervention following loose seton replacement will be assessed through medical record review and structured participant interview. A participant will be classified as having experienced the outcome if at least one of the following occurs during follow-up: an unplanned outpatient visit, emergency department attendance, hospital readmission, or an additional medical, radiological, or surgical intervention related to the loose seton or anal fistula. The outcome will be reported as the number and percentage of participants experiencing at least one event. This is a binary outcome (0 = no event; 1 = one or more events), with a value of 1 indicating a worse outcome.