Rationale and impact
This section briefly explains why the committee made the recommendations and how they might affect practice. It links to details of the evidence and a full description of the committee's discussion.
The recommendations apply to people with ileocolonic Crohn's disease who have had complete macroscopic resection and who have no residual active disease. This is the population covered in the studies the committee reviewed. The committee was aware that a proportion of people could still have residual active disease after surgery. It agreed that in these people, their disease is not in remission and the recommendations in the section on inducing remission in Crohn's disease would apply.
The evidence showed that azathioprine in combination with up to 3 months' metronidazole was effective in maintaining endoscopic remission. While there was some evidence of clinical benefit with azathioprine on its own, the effect was less certain. However, the committee included it as an option because some people have trouble tolerating metronidazole. The committee did not recommend metronidazole alone because, based on the evidence and their clinical experience, the potential benefits did not outweigh the potential harms (or adverse effects). Azathioprine can also be difficult to tolerate, and can cause adverse effects, so the committee looked at mercaptopurine as an alternative. However, mercaptopurine is not cost effective for maintaining remission because it has a high cost relative to the limited benefits it provides. The committee also reviewed the evidence for aminosalicylates (such as mesalazine). The evidence on relapse rates (assessed endoscopically) showed that aminosalicylates were not clinically or cost effective. Because of this, the 2012 recommendation on aminosalicylates was removed.
The committee made a recommendation on monitoring because of the tolerability issues and potential adverse effects of azathioprine and metronidazole. This is based on the 2012 recommendation on monitoring azathioprine when using it to induce remission.
There was limited evidence available for biologics, and a lot of uncertainty around how much benefit they provide. Biologics are also expensive, and all these factors together mean that they are not currently cost effective when compared with the other options for maintaining remission. To avoid unnecessarily changing treatments for people who started taking biologics before this guideline was published, the committee made a recommendation to cover this group.
The committee made a recommendation against offering budesonide because evidence shows that it is not beneficial in maintaining remission after surgery.
None of the included studies looked specifically at maintaining remission for children and young people after surgery, so the committee did not make separate recommendations for this population. In their experience children and young people are offered the same post-surgery treatment as adults.
There was no randomised controlled trial evidence on enteral nutrition. The committee made a research recommendation on enteral nutrition after surgery because it is sometimes used alone or with other maintenance therapy for maintaining remission after surgery.
The committee noted that the recommendations made are in line with current practice. There is variation across the UK in whether people receive 3 months of metronidazole after surgery.
The committee believe that the recommendation to not start biologics after surgery could potentially result in cost savings and maintain consistency in clinical practice.