Complex perianal disease is associated with poor outcome and requires early effective therapy. Corticosteroids are not effective in perianal fistulising Crohn’s disease, and antibiotics, immunosuppressants and anti-TNF therapy are required. It is important to consider combined medical surgical therapy after accurate imaging using an MRI scan of the pelvis. Drainage of any abscess at examination under anaesthesia and seton insertion are important before introduction of immunosuppressants and anti-TNF therapy. Long-term follow up of patients in a single centre reported responders to azathioprine having a reduced risk of perianal surgery (OR = 0.36; 95% CI: 0.27-0.46), but complex perianal fistulising Crohn’s disease generally requires combination therapy with anti-TNF and azathioprine. Patients with recent perianal disease without fistulae and aged 40 years or older respond better to azathioprine monotherapy. Response to monotherapy with azathioprine is often slow and incomplete. In the recent GETAID study of early administration of azathioprine versus conventional management in patients at high risk of disabling disease, a higher cumulative proportion of patients in the azathioprine group were free of perianal surgery. In patients not responding to anti-TNF therapy, thalidomide or tacrolimus may be considered. Hyperbaric oxygen may be used as adjunctive therapy where available. The role of adipose-derived stem cell injection requires further long-term studies. In prevention of post-operative recurrence of Crohn’s disease, azathioprine or 6-mercaptopurine had a favourable incremental cost-effectiveness ratio compared with no prophylactic therapy up to 1 year. In a Cochrane systematic review, azathioprine/6-mercaptopurine was associated with a significantly reduced risk of clinical recurrence [RR = 0.59, 95% CI: 0.38-0.92, number needed to treat (NNT) = 7] and severe endoscopic recurrence (RR = 0.6, 95% CI: 0.44-0.92, NNT = 4). Individual studies of prevention of post-operative recurrence using azathioprine/6-mercaptopurine have shown only modest benefit. In patients at high risk of relapse after surgical resection, anti-TNF therapy may be beneficial, but more data is required from ongoing studies. Strategies to prevent post-operative recurrence in Crohn’s disease are evolving but need further refinement.
Ghosh, Iacucci (2014). Role of immunosuppressives in special situations: perianal disease and postoperative period. Digestive diseases (Basel, Switzerland), 2014 ;32 Suppl 1():92-5. https://www.ncbi.nlm.nih.gov/pubmed/25531359