The purpose of the ATLANTIS trial is to find out whether a tablet called amitriptyline helps people with irritable bowel syndrome (IBS).

About 1 in 10 people report on-going tummy pain or bloating and changes in bowel habit. These are typical symptoms of IBS. IBS is a long-term condition. It causes discomfort and distress, reducing people’s quality of life. There is no cure and it can be difficult to treat. IBS is also expensive, because people often visit their GP, take time off work, or need to see specialists.

Amitriptyline can be used to treat IBS at a low dose. Amitriptyline is also used in higher doses to treat depression. We believe it helps with IBS because it relieves pain and changes bowel activity, rather than because it affects mood. Small studies of amitriptyline have shown promising results and guidelines suggest trying it when people with IBS have ongoing symptoms. We are unsure whether the drug benefits people with IBS who are looked after by their GP, as there has been no large study.

We plan to recruit over 500 participants from GP practices across West Yorkshire, Bristol and Southampton. Amitriptyline will be prescribed by a GP, at a low dose, when other treatments (e.g. changes to diet) have not worked. To find out if it works, this trial will compare the amitriptyline to a dummy treatment called a placebo.

We are interested in its effect on both the symptoms of IBS, costs of managing it, and whether use of amitriptyline in people with IBS is likely to offer value for money to the NHS. To do this, we will ask people to fill out questionnaires about their IBS symptoms, mood, and, quality of life.

We will also interview participants and GPs about their experience of being in the trial.