Cognitive behavioural therapy in addition to antispasmodic therapy for irritable bowel syndrome in primary care: randomised controlled trial

Abstract

OBJECTIVES: To determine whether cognitive behavioural therapy (CBT) in addition to antispasmodic treatment offers a cost-effective benefit to primary care patients with irritable bowel syndrome (IBS) and to identify predictors of outcome. DESIGN: This was a randomised controlled trial in primary care of the addition of CBT to standard general practice management of IBS, using the antispasmodic agent mebeverine hydrochloride. The study set out to compare the addition of a standardised package of IBS-specific CBT to treatment with mebeverine hydrochloride. SETTING: Ten general practices, serving a population of around 45,000 patients, located principally in south London, with some patients resident in north London. PARTICIPANTS: Patients identified as having IBS by their GPs, aged between 17 and 54 (mean 34) years and predominantly white; 82% were female and half had had IBS for more than 5 years. INTERVENTIONS: Practice nurses delivered CBT in a randomised trial of the addition of CBT to mebeverine in patients who had IBS of moderate or greater severity after 2 weeks of GP care and 4 weeks of mebeverine. The Symptom Severity Scale (SSS) was used to identify patients with moderate or severe IBS. Patients who continued to report moderate or severe IBS after 4 weeks of mebeverine at a dose of 270 mg three times a day were randomised to receive six sessions of CBT in addition to mebeverine (72 patients) or mebeverine alone (77 patients). These patients were followed at 3, 6 and 12 months after treatment. As part of the baseline evaluation, blood tests for antiendomysial and antigliadin antibodies were carried out on 141 patients to determine the prevalence of coeliac disease in this population. MAIN OUTCOME MEASURES: The principal outcome measure was the SSS. Others included the Hospital Anxiety and Depression Scale, psychopathology, the Work and Social Adjustment Scale (WASA, disability), a modified version of the Illness Perception Questionnaire (illness perceptions), the Beliefs about Medicine Questionnaire (attitudes to medication), the Reported Adherence to Medication Scale (adherence to prescribed medication), the Client Service Receipt Inventory (economic analysis), the Cognitive Scale for Functional Bowel Disorders (illness cognitions) and the Behaviour Scale for IBS (IBS coping behaviour). RESULTS: The addition of CBT produced a significant benefit compared with the mebeverine-only group at 3 months after treatment on all outcome measures, except for the adherence to medication scales. The difference between the groups was 107.8 points on the SSS, 24.5 points on question 4 of the SSS and 6.3 points on the WASA, representing therapeutic gains of approximately 20%, 28% and 40%, respectively. However, there was also evidence that these improvements began to wane, so that at 6 and 12 months follow-up significant therapeutic benefit of the addition of CBT could only be detected on question 4 of the SSS and on the WASA. The behaviour scale for IBS detected significant, positive changes in coping behaviours at up to 6 months after treatment. Three factors predicting a poor outcome were identified: male gender, believing that IBS had serious consequences and belief in an external aetiology, all of which were associated with greater than average disability at follow-up. The addition of CBT to mebeverine did not reduce overall treatment or social costs. The nested study on testing for coeliac disease provides cautious support for the inclusion of antiendomysial and antigliadin antibody testing in the investigation of patients thought to have IBS. CONCLUSIONS: Specially trained practice nurses can provide effective CBT to primary care patients with a clinical diagnosis of IBS, which although effective does not reduce service or social costs. Using a variety of measures the beneficial therapeutic effects of the addition of CBT to antispasmodic therapy persist for up to 6 months. Future research might include studies of the long-term follow-up of IBS patients treated with CBT, cost-benefit analyses comparing CBT with other therapeutic approaches to IBS, and evaluating means of training both non-specialist health professionals and GPs to deliver CBT.