Well-being in IBS: Strengths and Happiness (WISH)

Measured by proportion of PP sessions completed by participants in each group.

Participants will provide ratings of ease after each PP exercise, measured on a 10-point Likert scale (0=very difficult, 10=very easy). Weekly ratings will be averaged to provide an overall ease of the exercises.

Participants will provide ratings of utility after each PP exercise, measured on a 10-point Likert scale (0=not at all helpful; 10=very helpful). Weekly utility ratings will be averaged to provide an overall utility score of the exercises.

The positive affect items on the Positive and Negative Affect Schedule (PANAS), a well-validated scale used in other intervention trials and in patients with medical illnesses, will be used to measure positive affect (Range: 10-50). Higher scores indicate higher levels of positive affect. Change will be calculated by subtracting the score at baseline from the score at 9 weeks.

Life Orientation Test-Revised is a well-validated 6-item instrument used to measure dispositional optimism (Range: 0-24). Higher scores indicate higher levels of optimism. Change will be calculated by subtracting the score at baseline from the score at 9 weeks.

The Hospital Anxiety and Depression Scale (HADS)-depression subscale will be used to measure depression. This is a well-validated scale with few somatic symptom items that can confound mood/anxiety assessment in medically-ill patients (Range: 0-21). Higher scores indicate higher levels of depression. Change will be calculated by subtracting the score at baseline from the score at 9 weeks.

The Hospital Anxiety and Depression Scale (HADS)-anxiety subscale will be used to measure anxiety. This is a well-validated scale with few somatic symptom items that can confound mood/anxiety assessment in medically-ill patients (Range: 0-21). Higher scores indicate higher levels of anxiety. Change will be calculated by subtracting the score at baseline from the score at 9 weeks.

Measured by the Visceral Sensitivity Index (VSI) score, a validated self-report measure of anxiety specific to visceral sensations (Range: 0-75). Higher scores indicate higher levels of GI-specific anxiety. Change will be calculated by subtracting the score at baseline from the score at 9 weeks.

Measured by the Brief Resilience Scale (BRS) (Range: 6-30), a reliable 6-item measure of the ability to "bounce back" or recover from stress. Higher scores reflect greater bounce back resilience. Change will be calculated by subtracting the score at baseline from the score at 9 weeks.

Measured by the 25-item Connor-Davidson Resilience Scale (CD-RISC) (Range: 0-100), a reliable and validated measure of resilience, defined as the ability to cope with stress and adversity. Higher scores reflect greater resilience. Change will be calculated by subtracting the score at baseline from the score at 9 weeks.

Measured by the Pain Catastrophizing Scale (PCS), a widely used tool to assess cognitive and affective responses to pain (Range: 0-52). Higher scores indicate higher levels of pain-related anxiety. Change will be calculated by subtracting the scores at baseline from the scores at 9 weeks.

Measured by the Perceived Stress Scale (PSS) (Range: 0-40). Higher scores indicate higher perceived stress. Change will be calculated by subtracting the score at baseline from the score at 9 weeks.

Measured by the IBS Quality of Life (IBS-QOL) score (Range: 0-100), a validated disease-specific instrument measuring quality of life. Higher scores indicate better IBS-specific quality of life. Change will be calculated by subtracting the score at baseline from the score at 9 weeks.

Measured by the IBS symptom severity score (IBS-SSS) score (Range: 0-500), a validated disease-specific instrument measuring symptom severity. Change will be calculated by subtracting the score at baseline from the score at 9 weeks.

Measured by the self-report International Physical Activity Questionnaire (IPAQ). This measure assesses the types of intensity of physical activity that people do as part of their daily lives. All activities are converted to multiples of resting energy expenditure (MET) minutes per week. Change will be calculated by subtracting the score at baseline from the score at 9 weeks.

Measured with a single question inquiring if the participant followed the diet with possible responses including: never, a quarter of the time, half of the time, three-quarters of the time, or always. A score of 0-4 (0=never, 4=always) will be applied. Change will be calculated by subtracting the score at baseline from the score at 9 weeks.

Measured with a 3-item questionnaire from the Heart and Soul study. Participants will be categorized as adherent (>75% of the time) versus non-adherent (<75% of the time), and this will be compared between baseline and 9 weeks.

Measured by the Nine Item Avoidant/Restrictive Food Intake Disorder screen (NIAS) (Range: 0-45), a validated tool to assess avoidant/restrictive eating patterns. Higher scores indicate higher levels of avoidant/restrictive eating patterns. Change will be calculated by subtracting the score at baseline from the score at 9 weeks.

Measured by the Eating Disorder Examination Questionnaire 8 (EDE-Q8) (Range: 0-6), an 8-item questionnaire that assesses eating disorder symptoms over the past 28 days. Higher scores indicate higher levels of eating disordered symptoms. Change will be calculated by subtracting the score at baseline from the score at 9 weeks.

Measured by the Rome IV Diagnostic Questionnaire - Irritable Bowel Syndrome (IBS) Module. This questionnaire provides inclusion criteria for IBS for clinical research studies. To meet criteria for IBS, participants must have the following for the past 3 months: (1) recurrent abdominal pain at least weekly; (2) pain associated with 2 or more of the following criteria: (a) related to defecation at least 30% of occasions; (b) associated with change in stool frequency at least 30% of occasions; (c) associated with change in stool form at least 30% of occasions; and (3) symptom onset at least 6 months prior to diagnosis.

Participants will provide ratings of optimism before and after each positive psychology exercise, measured on a 10-point Likert scale (0-10). Higher scores indicate higher levels of optimism.

Participants will provide ratings of happiness before and after each positive psychology exercise, measured on a 10-point Likert scale (0-10). Higher scores indicate higher levels of happiness.