Therapeutic drug monitoring in inflammatory bowel disease : implementation, utilization, and barriers in clinical practice in Scandinavia

Background and aims Therapeutic drug monitoring (TDM) may optimize biologic and thiopurine therapies in inflammatory bowel disease (IBD). The study aimed to investigate implementation and utilization of TDM in Scandinavia. Methods A web-based questionnaire on the use of TDM was distributed to Scandinavian gastroenterologists via the national societies. Results In total, 297 IBD physicians prescribing biologic therapies, equally distributed between community and university hospitals, were included (response rate 42%) (Norway 118 (40%), Denmark 86 (29%), Sweden 50 (17%), Finland 33 (11%), Iceland 10 (3%)). Overall, TDM was applied during biologic therapies by 87%, and for TNF-inhibitors >90%. Among the users, reactive and proactive TDM were utilized by 90% and 63%, respectively. Danish physicians were significantly less inclined to use TDM compared to other Scandinavian countries; (58% vs 98%); OR 0.03 [0.01-0.09], p 10 IBD patients/week (p = 0.005). TDM scenarios were interpreted in accord with available evidence but with discrepancies for proactive TDM. The main barriers to TDM were lack of guidelines (51%) and time lag between sampling and results (49%). TDM of thiopurines was routinely used by 87%. Conclusion TDM of biologic and thiopurine therapies has been broadly implemented into clinical practice in Scandinavia. However, physicians call for TDM guidelines detailing indications and interpretations of test results along with improved test response times.Peer reviewe

Experimental mechanical and chemical compaction of carbonate sand

International audienceUniaxial compression tests were conducted on bioclastic sand and crushed calcite crystals. Mechanical and chemical processes were investigated to better quantify petrophysical properties of carbonates and their evolution with burial or during fault zone processes. The grain size was in the range 63-500 μm, and the samples were saturated with water in equilibrium with carbonate, glycol, decane, or air. During loading, effective stress was increased to 32 MPa. Mechanical compaction processes (i.e., grain rearrangement, crushing) could be separated from chemical processes (i.e., pressure solution, subcritical crack growth). P and S waves monitored during the tests showed low velocity in samples saturated with reactive fluids. This suggested that chemical reactions at grain contacts reduced the grain framework stiffness. Creep tests were also carried out on bioclastic sand at effective stress of 10, 20, and 30 MPa. No creep was observed in samples saturated with nonreactive fluids. For all the samples saturated with reactive fluids, strain as a function of time was described by a power law of time with a single exponent close to 0.23. Parameters controlling creep rate were, in order of importance, grain size, effective stress, and water saturation. Microstructural observations showed that compaction of bioclastic carbonate sand occurred both mechanically and chemically. Crack propagation probably contributed to mechanical compaction and enhanced chemical compaction during creep. Experimental compaction showed that compaction of carbonates should be modeled as a function of both mechanical and chemical processes, also at relatively shallow depth and low temperature