London: People with Crohn's disease -- a serious bowel condition -- are more likely to experience a recurrence after surgery if they continue to smoke, new research has found.
Crohn's disease occurs when the immune system attacks the lining of the gut and bowel to cause severe inflammation. It results in abdominal pain, urgent diarrhoea, sickness and profound lethargy.
Doctors recommend people with the condition stop smoking to avoid their illness worsening.
"Our study confirms that the most important thing somebody with Crohn's disease can do for their health is not to smoke," said Jack Satsangi, Professor at University of Edinburgh in Britain.
Most patients with Crohn's disease require surgery to remove the affected section of their bowel. Surgery is not curative, however, and the condition often relapses.
The researchers also assessed whether a drug treatment that is commonly used in treating the disease is effective at preventing it from coming back after surgery.
They found that the therapy had limited beneficial effects for non-smokers in preventing relapse after surgery. It did, however, offer protection for smokers.
A class of drugs called thiopurines have often been prescribed to patients after surgery to try to prevent relapse but until now, it was not clear whether the therapy offers any benefit.
The researchers conducted a trial of the therapy involving 240 people with Crohn's disease.
Patients were monitored for three years after they had undergone surgery. Some 128 patients were treated with a drug from the thiopurine family called mercaptopurine and 122 were given a dummy medicine.
Only three of 29 smokers treated with the therapy experienced a relapse compared with 12 of 26 who received the dummy drug.
The rate of relapse in the non-smoking group was much lower and was unaffected by treatment with the medicine, showed the findings published in The Lancet Gastroenterology and Hepatology.
"There is an unmet need to identify therapies or life-style changes that prevent Crohn's disease recurrence after surgery to avoid patients having to undergo multiple operations," Satsangi said.