Shahabi 2016.

Study characteristics
Methods	Study design: RCT Funding: Gail and Gerald Oppenheimer Family Foundation and Marcled Foundation Published protocol/trial registration: no
Participants	Men and women aged 18–65 years who reported their primary medical complaint as chronic abdominal pain or discomfort and associated bowel habit changes consistent with ROME III criteria for IBS. Number randomised: 35 Age: mean 36.3 (SD 12.8) years % Female: 88.9% SES and ethnicity: education 96.2% attained high school diploma; 40.7% married, 48.2% single Inclusion criteria Men and women aged 18–65 years Primary medical complaint was chronic abdominal pain or discomfort Associated bowel habit changes consistent with ROME III criteria for IBS Physically able to engage in an exercise programme Consumed < 2 drinks of alcohol per day Not practicing yoga more than once per week upon starting treatment Exclusion criteria Major psychiatric disorders, such as schizophrenia or bipolar disorder (not those with mild‐to‐moderate anxiety or depression symptoms or on psychotropic medications, if on a consistent dose for 3 months) Recruitment: flyers in the community, Internet announcements and referrals from University of California, Los Angeles and local physicians Recruitment rate: not reported Region: University of California, Los Angeles, USA
Interventions	Number of experimental conditions: 2; exercise intervention and walking control Number of participants (analysed): intervention: 17; control: 10 Description of intervention: 16 group sessions of yoga offered on a biweekly basis, led by an Iyengar yoga‐certified instructor. Sessions lasted about 60 minutes. At each session, participants alternated between practicing 2 sequences of Iyengar yoga postures. Postures were first demonstrated by the instructor who also discussed the health benefits of each posture. Participants were encouraged to practice select postures at home between sessions. Pictures of the poses provided to help with home practice, and instructors discussed ways of facilitating home practice (e.g. use of cushion as a bolster). Sequences and home practice postures consisted of seated poses, inversions, backbends, twists and restorative supine poses. Postures selected because they were believed to be therapeutic for abdominal symptoms associated with IBS. Senior Iyengar yoga instructors were consulted to select postures, and sequences were approved by Mr Iyengar, the founder of the Iyengar School of Yoga, in India. Because Iyengar yoga emphasises alignment, props including bolsters, chairs, belts and blocks were used to help achieve postures. Duration: 8 weeks Number of contacts: 16 Setting: university Modality: supervised Interventionist: Iyengar yoga‐certified instructor, physical trainers Integrity: senior Iyengar yoga instructors were consulted to select postures, and sequences were approved by the founder of the Iyengar School of yoga, in India. Date of study: not reported Description of control: 16 group sessions of non‐aerobic, moderate paced, outdoor walking led by physical trainers who set the pace and led discussion during each session. Walking sessions were offered on a biweekly basis and lasted about 60 minutes. Discussion during each walking session focused on health benefits of walking and physical activity.
Outcomes	Primary outcomes Overall GI symptoms (21‐point NRS) Abdominal pain severity (21‐point NRS) Positive And Negative Affect Schedule (PANAS‐X) – Negative Affect Scale only at end of treatment (8 weeks) and 6‐month follow‐up Secondary outcomes GI symptom‐specific anxiety – Visceral Sensitivity Index (VSI) Severity of somatic symptoms – Patient Health Questionnaire‐15 State anxiety – Spielberger State Anxiety Inventory Outcome relating to reported adverse events: not reported Outcome assessment time points: 8 weeks – end of intervention; 26 weeks – post‐intervention follow‐up Preplanned subgroup analyses: none Unplanned subgroup analyses: – Lost to follow‐up: 8 (23%) until end of intervention (intervention: 5 (14%); control: 3 (9%)); 15 (43%) at 6‐month follow‐up (intervention: 10 (29%); control: 5 (14%)) Analysis: per‐protocol
Notes	No specific MCID stated for any of the measured outcomes.
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Unclear risk	Insufficient information.
Allocation concealment (selection bias)	Unclear risk	Insufficient information.
Blinding of participants and personnel (performance bias) All outcomes	High risk	Group allocation was not blinded to participants, clinicians or researchers. However, it was not possible to blind participants and personnel for this intervention.
Blinding of outcome assessment (detection bias) All outcomes	Unclear risk	Insufficient information.
Incomplete outcome data (attrition bias) All outcomes	High risk	Rate of attrition was 23% at 8 weeks and 42% at 6 months, with uneven rates between groups and ITT analysis was not performed.
Selective reporting (reporting bias)	Unclear risk	No protocol or trial registration to determine whether outcomes reported were preplanned.
Other bias	Unclear risk	Uneven group sizes; differences in baseline characteristics including baseline bowel habits and current exercise habits.