TNF and inflammatory bowel disease: Regarding anti-TNF serum drug concentrations and antidrug antibody tests, gastroenterologists in the IBD interest group (group A) requested an average of 41.4 tests while gastroenterologists in the non-IBD interest group (group B) requested an average of 12.3 tests (P < 0.001, 95% CI 20.1–40.4; Figure 3; Table 3; Supplementary Table 5).