Vlieger 2007.

Study characteristics
Methods	RCT. 2 arms. Assessed at pretreatment, post‐treatment, 6 months, 1 year
Participants	End of treatment: n = 51 Start of treatment: n = 52 Sex: 39 F, 13 M Mean age = 13.3 years (SD 2.7) Source = paediatric gastroenterology department in hospital Diagnosis = functional abdominal pain (n = 31) and irritable bowel syndrome (IBS) (n = 22) Mean years of pain = 3.4
Interventions	"Gut‐directed hypnotherapy" "Standard medical care plus supportive therapy"
Outcomes	Primary pain outcome: weekly pain intensity Primary disability outcome: none Primary depression outcome: none Primary anxiety outcome: none Total pain intensity over 1 week (9‐point Faces Affective Pain Intensity Scale, reduced to 0 to 3 points, hence 0 to 21) Total pain frequency over 1 week (frequency reduced to 0 to 3 scale per day) Associated symptoms (nausea, vomiting, loss of appetite, flatus, nocturnal pain, pain on wakening, pain related to meals)
Notes	COI: not reported. Funding: "There was no external funding source."
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Low risk	"Patients were randomly allocated using a computerised random‐number generator for concealment to either HT or standard medical care." Comment: probably done
Allocation concealment (selection bias)	Low risk	"Patients were randomly allocated using a computerised random‐number generator for concealment to either HT or standard medical care." Comment: probably done
Blinding of outcome assessment (detection bias) All outcomes	Low risk	"Pain diaries were analysed by S. W. (medical student), who was blinded to the treatment arm." Comment: probably done
Incomplete outcome data (attrition bias) All outcomes	Unclear risk	Attrition was described, however significant differences between completers and non‐completers were not reported
Selective reporting (reporting bias)	Low risk	Data were fully reported