Table 2. Studies that discuss the effect of CBT on IBS.

CBT: cognitive behavioral therapy; IBS: irritable bowel syndrome; QoL: quality of life

Study	Author name/year	Study design	Sample size	Main points
Study 1	Lackner et al./2018 [15]	Randomized controlled trial	436 patients	The study compared CBT vs. education in the treatment of IBS. Patients were more responsive to CBT than education for IBS symptoms control
Study 2	Reme et al./2011 [16]	Randomized controlled trial	149 patients	This study supports that CBT has a positive impact on IBS symptoms due to communication between emotion, behavior, and cognition in the development of IBS
Study 3	Jang et al./2014 [17]	Randomized controlled trial	180 patients initially; 13 patients withdrew during the research for various reasons	The study showed the effect of CBT on IBS in female nursing students. CBT proved to be effective in improving QoL and reduced the symptoms of IBS
Study 4	Chilcot et al./2013 [18]	Randomized controlled trial	64 patients	The study showed CBT has a better effect on symptoms of IBS rather than usual treatment. CBT has a positive effect on IBS due to its impact on cognition rather than the mood
Study 5	Ljótsson et al./2013 [19]	Randomized controlled trial	195 patients	This study compared the impact of internet CBT and stress management on improving IBS symptoms. Internet CBT has a positive effect on IBS symptoms due to its ability to reduce gastrointestinal anxiety and not due to stress reduction
Study 6	Ljótsson et al./2010 [20]	Randomized controlled trial	85 patients	This study examined the role of CBT in developing mindfulness and exposure offered by the internet in controlling IBS symptoms. It showed that CBT via the internet is beneficial for controlling IBS symptom and improving patients’ QoL