Therapeutic drug monitoring in inflammatory bowel disease: too little too early?—comments on the American Gastroenterology Association Guideline

The management of inflammatory bowel disease (IBD) has advanced significantly in recent years, with increasing availability of biologic agents, the use of measurable objective biomarkers of inflammation (e.g., fecal calprotectin) and increasing use of therapeutic drug monitoring (TDM) to optimize individual therapies. IBD management has evolved towards a treat-to-target approach, of which TDM is an increasingly essential part. However, the clinical utilization of TDM varies globally and between institutions, and the ideal best practice use of TDM remains unclear. The recently published American Gastroenterology Association (AGA) TDM guideline attempted to address these issues for clinicians. It consisted of five recommendations on the use of TDM in IBD (1). Two of these recommendations considered anti-tumor necrosis factor (TNF)-α agents, with the remaining three relevant to thiopurines. Recommendations were not made on TDM of newer biologics agents such as vedolizumab and ustekinumab, due to the current paucity of data. The article was accompanied by a detailed technical review (2), a decision support tool (3), and a patient guide (4). The recommendations were developed by the AGA guideline panel, using the Grading of Recommendations Assessment, Development and Evaluation (GRADE) framework. A literature review was performed in March 2016, and the panel met in February 2017 before finalizing the guideline.