Letter: faecal calprotectin for the prediction of relapse in inactive inflammatory bowel disease – authors’ reply

We are grateful to Dr Yamamoto and colleagues for their comments1 on our article reporting the predictive value of a change in faecal calprotectin on risk of clinical relapse in patients with inactive inflammatory bowel disease (IBD).2 We agree that the value of faecal calprotectin for screening of inflammation in the proximal ileum remains to be elucidated, as well as its value for prediction of clinical relapse. The number of patients with ileal Crohn's disease in our study was small (n = 13) and would not allow a meaningful statistical analysis. Furthermore, some symptoms of mild ileal Crohn's disease may arise due to other reasons than persistent macroscopic inflammation,3 further diluting the endpoint of the study. We decided on a fixed interval of faecal calprotectin measurements at 3 months for practical reasons. As factors affecting variability of faecal calprotectin are still poorly studied, the optimal time interval of faecal calprotectin monitoring needs further assessment. The cost-effectiveness of pharmacological intervention based on faecal calprotectin is another important aspect that needs to be addressed, ideally by a randomised, controlled trial in a defined subgroup of patients. Some previous work, based on a randomised, controlled design, indicates that an increase in faecal calprotectin might justify a change in therapy.4 In summary, the role of serial measurements of faecal calprotectin for predicting relapse in IBD needs to be defined, and aspects such as optimum time intervals, subgroup-specific changes, and cut-offs to use, as well as the dynamics of faecal calprotectin assays, need to be standardised. The authors’ declarations of personal and financial interests are unchanged from those in the original article.2