Systematic review: The placebo effect of psychological interventions in the treatment of irritable bowel syndrome

Table 4 Comparison of outcome measurements

Author	Symptoms	Anxiety	Depression	Quality of life
Craske CBT-IE	Bowel Symptom Severity (BSS)	VSI	-	IBS-QOL (FA and IF)
	56%/89% = 63%	0%/44% = 0%	-	FA: 31/25 = 125%
				IF: 9/10 = 84%
Craske SM	BSS	VSI	-	IBS-QOL (FA and IF)
	56%/82% = 68%	0%/23% = 0%	-	FA: 31/17 = 184%
				IF: 9/14 = 64%
Drossmann	Mc Gill pain Questionnaire	-	-	IBS-QOL
	2.77/4.58 = 60%	-	-	4.8/9.35 = 51%
Gaylord	IBS-Symptom Severity Score	VSI	Brief state inventory-depression	IBS-QOL
	(IBS-SSS)	Brief State Inventory-anxiety
	42.2/68.8 = 61%	1.16/5.78 = 20%	0.78/1.49 = 52%	3.7/0.19 = 36%
		1.64/3.86 = 42%
Moser	IBS-Impact Scale (IBS-IS)	HADS	-	SF-36
		Hospital Anxiety and Depression Scale
	40.9/60.8 = 67%	0.5/3.7 = 14%	-	24/117.9 = 20%
Payne and Blanchard	Composite Primary Symptom Reduction (CPSR)	STAI (state)	BDI	-
		STAI (trait)
	25%/75% = 33%	FALSE	0.4/6.3 = 6%	-
		FALSE
Shinozaki	Adequate Relief	State Trait Anxiety Inventory (state)	Self rating depression scale	SF-36
	Self Reported IBS Questionnaire (SIBSQ)	STAI (trait)	(SDS)
	30/81.8 = 37%	3.2/2.8 = 114%	0.1/1.8 = 6%	15.5/58.2 = 27%
	19.6/3.2 = 612%	4/1.5 = 267%

The percentages were calculated by dividing the treatment effect in the placebo group by the treatment effect in the intervention group and multiplying the quotient by 100. FA: Food avoidance; IF: Interference; VSI: Visceral sensitivity index.