The requirement of bowel surgery is dramatically reduced by up to 60% in patients who develop Crohn's disease if they receive prolonged treatment with drugs called thiopurines, says a new study.

Crohn's affects more than quarter-of-a-million people in the UK leading to an inflamed intestine.

Researchers from St George's, University of London, St George's Hospital, London and Imperial College, London, monitored more than 5,000 patients in the UK living with Crohn's disease for more than 20 years and looked at the effect of thiopurine drugs that suppress inflammation in the gut.

Gastroenterologist Dr Richard Pollok, an honorary senior lecturer at St George's, University of London, said "Our discovery is timely since new guidelines from the USA have played down the benefits of these drugs in favour of newer agents.

"A year of treatment with the newer 'biologics', which are administered by injection, cost about £10,000 more compared to thiopurines.

"We try to avoid surgery but some patients face multiple procedures because the disease can flare up again particularly where the intestine has been rejoined.

"The fact that thiopurines can cut the need for surgical intervention and remain affordable is good news for patients and the NHS."

They found patients taking thiopurines, such as Azathioprine, for more than 12 months had a 60% reduction within the first 5 years of diagnosis.

Thiopurines have been used in the treatment of inflammatory bowel conditions like Crohn's disease since the 1970s but their long-term benefits have just come to light.

There has been a major increase in the number of patients who receive these drugs in the past decade and rates of surgery in patients with this condition have dropped, partly as a result of these and other treatments.

But up to a quarter of patients still go on to have their first corrective surgery to remove the worst affected areas within 5 years of being diagnosed.

The study, published in the American Journal of Gastroenterology, was funded by the National Institute for Health Research.