Table 2.

Other instruments

PRO Name	Number of Items and item content	Scoring
IBS-SSS [12]	Five items assessing abdominal pain, abdominal distension, bowel dysfunction, and quality of life/global well-being as reported by patients.	The IBS-SSS total score is calculated by summing the five item scores, resulting in a total score ranging from 0 to 500, with higher scores reflecting higher severity of IBS The IBS-SSS has no specified recall period
SF-12 [17]	Twelve items assessing dimensions: physical functioning, role physical, role emotional, bodily pain, general health, vitality, social functioning, and mental health.	Scores for each dimension are obtained by summing the corresponding item values. The resulting scores are then rescaled from 0 (worst possible health state measured by the questionnaire) to 100 (best possible health state) In addition, two summary scores, the physical component scale (PCS-12) and the mental component scale (MCS-12), are calculated The SF-12 has a recall period of 1-week
IBS-QOL [13]	Thirty-four items assessing quality of life with impact being assessed across eight domains: dysphoria (eight items), interference with activity (seven items), body image (four items), health worry (three items), food avoidance (three items), social reaction (four items), sexual (two items), and relationships (three items)	All domain scores are converted to a 0 to 100 scale, with high scores representative of a better health state The summed global score is transformed to a 0-100 scale ranging from 0 (poor quality of life) to 100 (maximum quality of life) The IBS-QOL has a recall period of 4 weeks
PGI-S [18]	Item assessing the severity of IBS-D	Severity is measured on a scale of 1 (none) to 5 (very severe) scale The PGI-S has a recall period of “currently”
PGI-C [18]	Item assessing level of change in IBS-D	Change is measured on a scale of 1 (very much improved) to 7 (very much worse) The PGI-C has a recall period of 1 week