Review Article

Psychological Therapies in Patients with Irritable Bowel Syndrome: A Systematic Review and Meta-Analysis of Randomized Controlled Trials

Table 1

Risk of bias assessment in the included trials.

Author, year (reference)Randomization methodAllocation concealmentBlindingBaseline imbalanceLost to follow-upSource of funding

Corney et al., 1991 [22]NRUnclearNRNo significant differences2.38%NR

Greene and Blanchard, 1994 [25]NRNRNRMatched subjects (GI symptoms, axis I psychiatric diagnosis, sex, duration of IBS, and age)7.14%NFP

Fernandez et al., 1998 [24]NRNRNRNo significant difference29.54%NFP

Vollmer and Blanchard, 1998 [36]NRNRNRMatched subjects (DSM-IV axis I psychiatric diagnosis, IBS subtypes, age, and duration of IBS symptoms)NRNFP

Heymann-Mnnikes et al., 2000 [26]UnclearUnclearNRNR7.7%NFP

Boyce et al., 2003 [20]Adequate
Random number generator
Sealed opaque envelopesRCC provider and data collectorParticipants were similar50.48%NFP

Creed et al., 2003; Hyphantis et al.,  
2009 [15, 27]
Adequate
Computer-generated random numbers Stratified by hospital and by pain severity
UnclearAssessorsNo difference in demographic or diagnostic variables13.62%NFP

Tkachuk et al., 2003 [35]NRNRNRMatched subjects (DSM axis I disorder, IBS subtype, IBS symptom duration, age, and gender)NRNFP

McCrone et al., 2008; Kennedy et al., 2005;Kennedy et al., 2006 [17, 28, 29]Adequate
Random number tables
UnclearNRNo significant difference11.41%NFP

Blanchard et al., 2007;Lackner et al., 2007 [19, 32]UnclearNot reportedNot reportedNo between-group differences at baseline10.48%NFP

Lackner et al., 2010;Lackner et al., 2008 [31, 33]Adequate
Computer-generated random numbers
UnclearNRNR16%NFP

Chilcot and Moss-Morris, 2013;Moss-Morris et al., 2010 [21, 34]Adequate
Computer-generated random numbers
Sealed opaque envelopsAssessorsIntervention group (CBT-TAU) reported higher HADS anxiety scale1.56%NFP

Craske et al., 2011; Wolitzky-Taylor  
et al., 2012 [23, 37]
Adequate
Random number generator
Opaque envelopesAssessorsNo statistically significant difference44.54%NFP

Gaylord et al., 2011 [12]Adequate
Computer-generated random numbers
NRPatients, data collectors, and managersNo statistically significant difference12%NFP

Labus et al., 2013 [30]Inadequate
Quasi-randomized
NoNoIntervention group (psychoeducation group) reported lower GI symptom severity score and higher HADS anxiety score and level of educationNRIncludes FPO
GlaxoSmithKline

NR: not reported; GI: gastrointestinal; IBS: irritable bowel syndrome; NFP: not-for-profit organization; DSM: Diagnostic and Statistical Manual of Mental Disorders; RCC: routine clinical care; CBT: cognitive behavioral therapy; TAU: treatment as usual; HADS: Hospital Anxiety and Depression Scale; FPO: for-profit organization.