IBD is a chronic disease whose treatment is sometimes complex because there is no established marker to indicate which treatments will work better on each patient. In the past years, studies have been performed to determine response-related factors, with recent interest in genetic predisposition to explain loss of response.1 Development of antiTNF-α antibodies (immunogenicity) has been related to the loss-of-response to antiTNF drugs and to the development of side effects.2, 3, 4, 5 Based on this, some authors link response to biologics and tolerance to having the HLA-DQ A1*05 allele, and have therefore proposed determining this allele to decide what to prescribe.2, 3, 5

Besides genetics, other factors such as the amount of inflammation may influence response to biologic treatment and, therefore, treatment duration. This depends on disease extension,6 flare severity,1 having perianal disease7 or extraintestinal symptoms.1 The type of biologic that is used8 and co-treatments9, 10 also play an important role in therapeutic response, as well as side effects that may lead to treatment interruption. Nevertheless, the interaction of genetic, clinical and therapeutic factors on the risk of treatment interruption has not been widely studied, and even less with the most recent biological drugs.

Our hypothesis was that biological treatment discontinuation depends not only on HLA-DQA1*05, but also, and more importantly, on clinical and therapeutic factors in real-life-practice. Our objective was to evaluate the influence of clinical and therapeutic factors, along with HLA, in biological treatment discontinuation.