How effective are psychological therapies and antidepressants for irritable bowel syndrome?

Keywords: Irritable bowel syndrome, Antidepressants, Psychological therapies

Introduction

IBS is a long-term gastrointestinal disorder with no known structural or anatomical explanation. A diagnosis requires the presence of recurrent abdominal pain or discomfort, along with a change in bowel habit. It is estimated that the condition affects 5–20% of the general population.

Patients with IBS are more likely to suffer from coexistent mood disorder, anxiety and neuroticism, and report a low quality of life. A significant proportion of patients with the condition who consult in tertiary care have an underlying psychiatric illness.

Although numerous reviews have examined whether antidepressants and psychological therapies have a beneficial effect on IBS symptoms, there is no clear consensus.

This uncertainty is reflected in British Society of Gastroenterology guidelines on managing the condition, which state that evidence for any benefit of tricyclic antidepressants is conflicting, and benefits may be limited to an improvement in pain. The guidelines therefore recommend their use as a second-line treatment for this symptom. Similar is said for the role of psychological therapies, while the role of selective serotonin reuptake inhibitors (SSRIs) in managing IBS is not specified.

The study

The review attempted to address this uncertainty and to estimate the effect of antidepressants and psychological therapies on the improvement or cure of IBS symptoms.

The authors carried out a systematic review and meta-analysis of randomised controlled trials. They searched Medline and Embase (up to May 2008) and the Cochrane Central Register of Controlled Trials (2007) (formerly the Cochrane Controlled Trials Register).

Thirty-two trials were eligible for inclusion and these were based in primary, secondary or tertiary care. These trials had examined the effect of antidepressants and/or psychological therapies in patients over 16 years with a diagnosis of IBS:

• Nineteen trials compared psychological therapies to control therapy or a doctor’s ‘usual management’;
• Twelve compared antidepressants to placebo;
• One compared both psychological therapy and antidepressants to placebo.

The trials that compared antidepressants to placebo included a total of 789 patients, while the psychological therapy trials included 1,278 patients. The authors extracted and pooled adverse events data, something that had not been carried out by previous investigators.

Study quality was generally good for antidepressant trials but poor for those on psychological therapies.

Findings

The review revealed a significant benefit of antidepressants over placebo in treating IBS. The relative risk of IBS symptoms lasting with antidepressants versus placebo was 0.66, and tricyclic antidepressants and SSRIs were found to be equally effective.

The overall treatment effect was very similar for psychological therapies, with the most evidence for cognitive behavioural therapy. Multi-component psychological therapy, dynamic psychotherapy and hypnotherapy were also effective in IBS, though in smaller numbers of patients. Relaxation therapy did not have a statistically significant effect on the condition, although there were few eligible published studies on this. The relative risk of symptoms persisting with psychological therapies was 0.67.

The number needed to treat was four for both interventions (antidepressants and psychological therapies).

Antidepressants were found to be less effective in patients recruited from tertiary care, but the authors say this is not surprising as it is likely that these patients’ symptoms are the most difficult to treat.

Adverse events were more common in patients assigned to antidepressants than placebo, but this was not statistically significant. None of the events were serious; the most commonly reported were drowsiness and dizziness.

The fact that the majority of trials only followed up patients for 8–12 weeks means that the effect of both antidepressants and psychological therapies on IBS symptoms in the longer term remains unknown.

Conclusion

The finding of the benefits of antidepressants over placebo is an important one. Previous systematic reviews have given conflicting evidence of their efficacy, and therefore current national guidelines for managing IBS make conflicting or vague recommendations for the role of antidepressant therapy in treating IBS.

Psychological therapies may have a role for patients who do not respond to conventional medical treatment, but further data is needed before any firm recommendations can be made.

This systematic review has demonstrated that both antidepressants and psychological therapies, particularly CBT, are efficacious in the short-term treatment of IBS.

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