Cognitive behavioural therapy (CBT) for irritable bowel syndrome (IBS): 24 month follow-up of ACTIB trial participants

Background: IBS is common, affecting 10-20% of the adult population with many people experiencing ongoing symptoms despite first line therapies. Cognitive behavioural therapy (CBT) is recommended in guidelines for refractory IBS but there is limited access to CBT for IBS and uncertainty whether benefits last in the longer term. ACTIB (Assessing Cognitive behavioural Therapy for IBS) was a large randomised controlled trial of two forms of CBT for patients with refractory IBS. ACTIB results showed, at 12 months, that both forms of CBT for IBS were significantly more effective than treatment as usual (TAU) at reducing IBS symptom severity and impact at 12 months in adults with refractory IBS. This follow-up study aims to evaluate 24 month clinical outcomes of participants recruited to the ACTIB trial.Methods: in the ACTIB three-arm randomised controlled trial, 558 adults with refractory IBS were randomly allocated to therapist-delivered telephone CBT (TCBT), web-based CBT with minimal therapist support (WCBT) or treatment as usual (TAU) and followed up for 12 months. Participants were adults with refractory IBS (clinically significant symptoms for ≥12 months despite first-line therapies), recruited by letter and opportunistically from 74 general practices and three gastroenterology centres in London and South of England between 1st May 2014 and 31st March 2016. Primary outcome measures were IBS Symptom Severity Score (IBS-SSS) and Work and Social Adjustment Scale (WSAS) Intention-to-treat (ITT) analyses with multiple imputation were undertaken. This study was a non-pre-specified naturalistic follow-up and analysis of ACTIB trial participants at 24 months.Findings: 24 months follow-up of outcomes was achieved for 57·9% (323/558) participants, (119/186 in the Telephone CBT arm, 99/185 in the Web CBT arm, 105 /187 in the treatment as usual arm). At 24 months compared to treatment as usual: IBS-SSS was 40·5 (95% CI 15·0 to 66·0) points lower (p=0·002) in the Telephone CBT arm and 12·9 (95% CI -12·9 to 38·8) points lower (p=0·325) in the Web CBT arm. WSAS was 3·1 (95% CI 1·3 to 4·9) points lower (p<0·001) in the Telephone CBT arm and 1·9 (95% CI 0·1 to 3·7) points lower (p=0·036) in the Web WCBT arm. A clinically significant IBS-SSS change (≧50 points), baseline to 24 months, occurred in 84/119 (70·6%) of participants in the Telephone CBT arm , 62/99 (62·6%) in the Web CBT arm and 48/105 (45·7%) in the treatment as usual arm. There were no adverse no adverse events related to treatment.Interpretation: at 24 month follow-up, sustained improvements in IBS were seen in both cognitive behavioural therapy arms compared to treatment as usual, though some previous gains were reduced compared to the 12 month outcomes. IBS-specific CBT has the potential to provide significant long-term improvement in IBS, achievable within a usual clinical setting. Increasing access to CBT for IBS could achieve long-term patient benefit.Funding: UK National Institute for Health Research, trials number ISRCTN44427879