The case against routine post-operative therapy for prevention of recurrence in Crohn's disease.

Crohn's disease is inevitably characterized by episodes of relapse followed by remission. The majority of patients will require at least one resection, unfortunately many will have, at some time in the future, further recurrences requiring additional surgery. Faced with this clinical situation, the physician or surgeon may respond to the therapeutic imperative, i.e., it is better to do something rather than to do nothing at all (i.e., treat the patient). Because of these factors, various authors have suggested that the aminosalicylates or, in certain cases, azathioprine, should be prescribed following resection. From a health system point of view, the case for maintenance therapy must be reviewed against several criteria. First, the therapy to be prescribed must be safe for patients over the long term. For the most part, the safety profile of mesalamine has been well established. There is also increasing evidence for the safety of azathioprine when used in chronic inflammatory diseases such as rheumatoid arthritis. Second, there must be objective evidence of efficacy as assessed by randomized controlled, double-blind trials. To date, several trials have been performed, unfortunately, the most recent have only been reported in abstract form. The results of the trials have been contradictory with a mixture of positive and negative findings. There is a lack of consistency for both the dose response and preferred disease site, the use of placebos, the evaluation of outcome and the statistical analysis. Third, the cost-benefit ratio must favour the therapy. Calculation of the number to reat (NNT) to prevent one recurrence is often helpful. Finally, compliance in a group of patients who often decide on surgery so that they can stop taking medication must be considered. A variety of criteria have been developed to assist in making choices regarding prophylaxis. The first relates to the ease of treating the patient with recurrence. Some patients will respond promptly to conventional therapy and enter remission. Unfortunately, this is not the case for the majority of patients. We lack predictors of response. The second concerns the issue as to whether or not the condition to be prevented, recurrence, is a "serious" event. There would be little discussion of that issue at an IBD meeting! The third considers the possibility of adverse events related to the prophylaxis. Again, there does not appear to be concern related to safety. It is the final criterion regarding effectiveness that balances the argument against a routine recommendation for post-operative maintenance therapy.