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BACKGROUND: We aimed to determine the correlation between tissue and plasma infliximab concentrations in an outpatient ulcerative colitis (UC) cohort based on histologic disease activity in addition to their relationship with long-term clinical outcomes. We assessed intraparticipant variability in infliximab concentrations between adjacent intestinal samples and the correlation between disease activity and tumor necrosis factor-α (TNF-α). METHODS: A prospective cohort study was conducted in participants with UC receiving infliximab. Blood and 2 sigmoid colon biopsies were obtained at the index colonoscopy for infliximab and TNF-α quantification. Histological disease activity was assessed. Participants were followed for 2 years for the occurrence of hospitalization, surgery, disease relapse, and infliximab discontinuation. RESULTS: A positive correlation was observed between mean plasma and uninflamed tissue infliximab concentrations only (Rsâ =â 0.75, Pâ =â .0071). Lower mean tissue infliximab concentrations correlated with a shorter time to disease relapse vs those with higher mean tissue concentrations (Rsâ =â 0.77, Pâ =â .032). This was not seen when using plasma infliximab concentrations. Additionally, no significant intraparticipant variability of infliximab concentrations was observed for all participants independent of disease activity. Neither plasma nor tissue TNF-α correlated with disease activity. CONCLUSIONS: These findings support data generated in patients with Crohn's disease: plasma infliximab concentrations are reflective of infliximab exposure in tissue in the UC patient in remission, but not for those with active disease. Increasing tissue concentrations in the noninflamed tissues may improve durability of infliximab. Neither plasma nor tissue TNF-α appear to correlate with UC disease activity. Larger follow-up studies would be of benefit.
Plasma infliximab concentrations are reflective of infliximab exposure in tissue in the UC patient in remission, but not for those with active disease. Increasing tissue concentrations in the noninflamed tissues may improve durability of infliximab.
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Background: Cannabis is used by patients with Crohn's disease (CD) and ulcerative colitis (UC) as an alternative to, or in combination with, conventional therapies to treat symptoms such as abdominal pain, poor sleep, and reduced appetite. The clinical efficacy of cannabis for these disorders is controversial, with some studies showing harmful outcomes associated with its use. Previous studies suggest that cannabis is used by ~12% of patients with UC and ~16% of patients with CD in the USA despite legal prohibition. Methods: We conducted a prospective cohort study of adult patients with inflammatory bowel diseases (IBD) followed in a Canadian tertiary care center. Patients completed an online 40-question survey that included demographics, IBD disease history, cannabis use, and the Short Inflammatory Bowel Disease Questionnaire (SIBDQ). Results: Completed surveys were obtained from 254 participants (148 with CD, 90 with UC, and 16 with indeterminate colitis). Recent cannabis use was reported by 41% of CD and 31% of UC participants. Interestingly, only 46% of participants who used cannabis discussed their use with their physician. Participants who recently used cannabis reported more abdominal pain, poor appetite, and flatulence, and importantly this was associated with lower SIBDQ scores (recent use 37 vs non-recent use 40). Conclusions: Cannabis use among patients with IBD has more than doubled since its legalization. Cannabis use is associated with worse abdominal symptoms and quality of life. Physicians should inquire about cannabis use and optimize symptom control with evidence-based therapies.
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BACKGROUND: Regulatory guidance for Crohn's disease trials recommends coprimary efficacy end points that evaluate both symptoms and mucosal inflammation. We aimed to characterize the operating properties of commonly used disease activity assessments alone and in combination. METHODS: Endoscopic and clinical data were available for 129 participants from the Study of Biologic and Immunomodulator Naïve Patients in Crohn's Disease trial. Readers scored the Simple Endoscopic Score for Crohn's Disease and the Crohn's Disease Endoscopic Index of Severity using standardized conventions. Index reliability was determined using intraclass correlation coefficients. Index responsiveness was assessed using standardized effect sizes based upon treatment assignment. Outcomes were evaluated for optimal sensitivity to treatment effect. RESULTS: Substantial inter-rater reliability was observed when the Simple Endoscopic Score for Crohn's Disease and Crohn's Disease Endoscopic Index of Severity were used as continuous measures (intraclass correlation coefficient, 0.64; 95% confidence interval [CI], 0.50-0.73; and 0.62 95% CI, 0.36-0.77) compared with moderate reliability when dichotomized (0.46; 95% CI, 0.26-0.65; and 0.51; 95% CI, 0.00-0.78). The Simple Endoscopic Score for Crohn's Disease, Crohn's Disease Endoscopic Index of Severity, patient-reported outcome-2, and Crohn's Disease Activity Index were similarly responsive (standardized effect size, 0.43, 95% CI, 0.05-0.81; 0.38, 95% CI, 0.0-0.76; 0.53, 95% CI, 0.15-0.91). A composite outcome of Crohn's Disease Activity Index scoreâ <150 and Crohn's Disease Endoscopic Index of Severity scoreâ <6 was most sensitive to treatment effect (28.9%; 95% CI, 11.0%-46.8%; Pâ =â .003). CONCLUSION: Endoscopic indices were more reliable as continuous measures. Composite outcomes including endoscopy improved sensitivity to treatment effect.
This study largely supports current regulatory guidance for Crohn's disease trials recommending coprimary efficacy end points evaluating both symptoms and mucosal inflammation. Continuous endoscopic measures are most reliable and improve sensitivity to treatment effect when employed in composite outcomes.
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We review concerns regarding use of placebo in clinical trials of inflammatory bowel disease. We propose alternate designs to overcome ethical issues, while providing data that are clinically relevant.
Subject(s)
Colitis, Ulcerative , Inflammatory Bowel Diseases , Humans , Inflammatory Bowel Diseases/drug therapy , Colitis, Ulcerative/drug therapyABSTRACT
Noninferiority trials are designed to demonstrate that a new treatment is not unacceptably worse than a standard treatment, considering an allowable difference termed the noninferiority margin. We highlight that selection of noninferiority margins at the time of study design can be biased toward wider margins that favor noninferiority claims. We discuss a clinically oriented approach to interpretation of results with a focus on confidence intervals and recommend that readers base their judgments regarding noninferiority on margins reflecting patient values and preferences rather than those set by investigators. We provide examples from trials in inflammatory bowel diseases.
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BACKGROUND AND AIMS: Endoscopic assessment of disease activity is integral for evaluating treatment response in patients with Crohn's disease (CD). We aimed to define appropriate items for evaluating endoscopic activity and conventions for consistent endoscopic scoring rules in CD. METHODS: A 2-round modified RAND/University of California at Los Angeles Appropriateness Method study was conducted. A panel of 15 gastroenterologists used a 9-point Likert scale to rate the appropriateness of statements pertaining to the Simple Endoscopic Score for CD, Crohn's Disease Endoscopic Index of Severity, and additional items relevant to endoscopy scoring in CD. Each statement was voted as appropriate, uncertain, or inappropriate based on the median panel rating and presence of disagreement. RESULTS: Panelists voted that it is appropriate for all ulcers to contribute to endoscopic scoring in CD, including aphthous ulcers, ulcerations at a surgical anastomosis, and anal canal ulcers (scored in the rectum). Endoscopic healing should reflect an absence of ulcers. Narrowing should be defined as a clear decrease in luminal diameter; stenosis should be defined by an impassable narrowing, and if occurring at the junction of 2 segments, scored in the distal segment. Scarring and inflammatory polyps were considered inappropriate for including in the affected area score. The optimal method for defining ulcer depth remains uncertain. CONCLUSIONS: We outlined scoring conventions for the Simple Endoscopic Score for CD and Crohn's Disease Endoscopic Index of Severity, noting that both scores have limitations. Therefore, we identified priorities for future research and steps for developing and validating a more representative endoscopic index in CD.
Subject(s)
Crohn Disease , Humans , Crohn Disease/diagnosis , Crohn Disease/therapy , Ulcer , Endoscopy, Gastrointestinal/methods , Endoscopy , Constriction, Pathologic , Rectum , Severity of Illness IndexABSTRACT
BACKGROUND: Multidisciplinary care involving exam under anesthesia (EUA) and tumor necrosis factor (TNF) inhibitors is recommended for perianal Crohn's disease. However, the impact of this combined approach is not well established. METHODS: We performed a comparative cohort study between 2009 and 2019. Patients with perianal Crohn's disease treated with EUA before anti-TNF therapy (combined modality therapy) were compared with anti-TNF alone. The primary outcome was fistula closure assessed clinically. Secondary outcomes included subsequent local surgery and fecal diversion. Multivariable analysis adjusted for abscesses, concomitant immunomodulators, and time to anti-TNF initiation was performed. RESULTS: Anti-TNF treatment was initiated 188 times in 155 distinct patients: 66 (35%) after EUA. Abscesses (50% vs 15%; P < .001) and concomitant immunomodulators (64% vs 50%; P = .07) were more common in the combined modality group, while age, smoking status, disease duration, and intestinal disease location were not significantly different. Combined modality therapy was not associated with higher rates of fistula closure at 3 (adjusted odds ratio [aOR], 0.7; 95% confidence interval [CI], 0.3-1.8), 6 (aOR, 0.8; 95% CI, 0.4-2.0) and 12 (aOR, 1.0; 95% CI, 0.4-2.2) months. After a median follow-up of 4.6 (interquartile range, 5.95; 2.23-8.18) years, combined therapy was associated with subsequent local surgical intervention (adjusted hazard ratio, 2.2; 95% CI, 1.3-3.6) but not with fecal diversion (adjusted hazard ratio, 1.3; 95% CI, 0.45-3.9). Results remained consistent when excluding patients with abscesses and prior biologic failure. CONCLUSIONS: EUA before anti-TNF therapy was not associated with improved clinical outcomes compared with anti-TNF therapy alone, suggesting that EUA may not be universally required. Future prospective studies controlling for fistula severity are warranted.
This comparative cohort study found that an exam under anesthesia before initiation of anti-tumor necrosis factor therapy in perianal Crohn's disease was not associated with higher rates of fistula closure, suggesting that an exam under anesthesia may not be universally required in patients with perianal Crohn's disease.
Subject(s)
Anesthesia , Crohn Disease , Rectal Fistula , Humans , Cohort Studies , Crohn Disease/drug therapy , Tumor Necrosis Factor Inhibitors/therapeutic use , Prospective Studies , Abscess , Rectal Fistula/drug therapy , Immunologic Factors/therapeutic use , Treatment Outcome , Tumor Necrosis Factor-alpha/therapeutic use , Retrospective Studies , Infliximab/therapeutic useABSTRACT
Background: The management of inflammatory bowel disease (IBD) requires frequent endoscopic assessment. It is unknown if measures put in place to reduce the spread of the virus SARS-CoV-2, including the delay of non-urgent patient assessments, resulted in deleterious outcomes for patients with IBD. Therefore, we aimed to determine if delays in endoscopy during the COVID-19 pandemic were associated with an increased risk of adverse IBD outcomes (emergency room, ER presentation, hospitalization, surgery, or escalation of drug therapy). Methods: A retrospective cohort study was performed in patients with IBD scheduled for outpatient endoscopies between March and August 2019 and 2020 at two tertiary care centers affiliated with Western University, London, Canada. Data pertaining to endoscopy timing, IBD drug prescription, ER attendance, hospitalization, and surgery were collected. Results: A total of 1160 endoscopies (2019, n = 718; 2020, n = 442) occurred during the study periods in 669 (2019) and 414 (2020) patients with IBD, respectively. More endoscopies were delayed in 2020 than 2019 (26.7% vs. 9.7%, respectively, P < 0.0001). Endoscopy delay was not associated with an increased risk of an adverse IBD outcome (OR = 1.23, 95%CI = 0.89-1.34, P = 0.20). Fewer adverse IBD outcomes were seen in the 2020 cohort who had endoscopy delays (n = 33/115, 28.7%) versus those without delay (n = 176/299, 58.9%, P < 0.0001). Conclusion: More endoscopy delays occurred during the COVID-19 pandemic; however, delays in general were not associated with adverse IBD outcomes, and in particular, endoscopy delays during the COVID-19 pandemic were associated with fewer deleterious IBD outcomes, suggesting that patients with IBD in need of urgent endoscopy were appropriately identified.
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Background: During the COVID-19 pandemic, the focus of many health care systems shifted in order to prioritize and allocate resources toward treating those affected by COVID-19. What this has meant for other patient populations remains unclear. We aimed to determine if there have been changes to acute care access for patients with inflammatory bowel disease (IBD) during the COVID-19 pandemic. Methods: A retrospective cohort study was performed in IBD patients seen during (March 1, 2020 to August 31, 2020) and before (March 1, 2019 to August 31, 2019) the COVID-19 pandemic. IBD-related emergency room (ER) access, hospitalization, inpatient care and follow-up and post-discharge ER access were assessed. Results: A total of 1229 participants were included. A higher proportion of patients accessed ER during the pandemic (44.6% versus 37.2%, P = 0.0097). A higher proportion of hospitalizations resulted from IBD-related ER visits during the pandemic period (41.6% versus 32.4%, OR = 1.48, 95% CI = 1.14 to 1.94, P = 0.0047), though length of stay was shorter (7.13 ± 8.95 days versus 10.11 ± 17.19 days, P = 0.015) and use of rescue infliximab was less. No change was seen in inpatient surgical intervention. Despite similar proportions of follow-up appointments post-hospital discharge (pre-pandemic, 77.9% versus pandemic, 78.3%), more ER visits occurred in the first 30 days following hospitalization for patients in the pandemic cohort (24.4% versus 11.1%, P = 0.0015). Conclusion: These data highlight the need for ER services and hospitalization amongst IBD patients during the COVID-19 pandemic. This suggests that a return to pre-pandemic IBD care infrastructure is needed to mitigate the need for acute care access.
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Crohn's disease (CD) is associated with reduced quality of life, increased absenteeism and high direct medical costs resulting from frequent hospitalizations and surgeries. Tumor necrosis factor-alpha inhibitors (TNFi's) have transformed the therapeutic landscape and enabled a shift from a symptom control to a treat-to-target strategy. The Effect of Tight Control Management on Crohn's Disease (CALM) trial demonstrated tight control (TC), with TNFi dose changes informed by biochemical markers of inflammation, achieved higher mucosal healing rates compared with conventional management (CM) based on symptoms. A Markov model compared TC and CM strategies from the perspective of the Canadian public payer using patient-observation data from the CALM trial. A regression model estimated weekly CD Activity Index-based transition matrices over a 5-year horizon and included covariates to improve extrapolation of outcomes beyond the 48-week trial assessment period. Costs of CD-related hospitalizations, biomarker tests and adalimumab injections were sourced from public data. Other direct medical costs, quality-adjusted life-years (QALYs), and incremental cost-effectiveness ratios (ICERs) were calculated. Absenteeism was monetized and included in a sensitivity analysis. Over the 5-year time horizon, TC reduced hospitalization costs by 64% compared with CM. Other direct medical costs were reduced by 22%; adalimumab costs increased by 38%, generating an ICER of $35,168 per QALY gained. Absenteeism costs were reduced by 54%, and, when that was included in the model, TC became dominant compared with CM. Management of CD with TC is cost-effective compared with CM in Canada and is dominant if indirect costs associated with absenteeism are included. Trial registration number: NCT01235689.
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BACKGROUND: Tumour necrosis factor (TNF) antagonists are an efficacious therapy used in the management of several immune-mediated inflammatory diseases, including inflammatory bowel disease (IBD) and psoriasis. However, since being prescribed more widely, reports of new-onset psoriatic lesions have began to emerge in the literature and are known as paradoxical psoriasis. AIM: To review the evidence available in both the dermatology and gastroenterology literature pertaining to the entity known as paradoxical psoriasis as it relates to IBD and to create a comprehensive guide to assist clinicians who treat this challenging patient population. METHODS: A literature search was conducted in PubMed to identify manuscripts that presented, discussed or summarised data pertaining to paradoxical psoriasis presenting in individuals with IBD. RESULTS: Paradoxical psoriasis is now thought to be a contradictory effect of TNF antagonist therapy leading to psoriatic lesions often within the first year of treatment. The underlying pathogenesis, although not completely understood, is likely related to an imbalance of inflammatory cytokines. The histological appearance, while similar to classical psoriasis, does have unique features. The clinical presentation can vary among patients but often presents during maintenance therapy for inflammatory bowel disease. Treatment options should be determined based upon the severity of the skin lesion, activity of the underlying inflammatory bowel disease and the patient's unique clinical history. CONCLUSIONS: The approach to paradoxical psoriasis in IBD should be discussed with a multidisciplinary team to optimise and preserve intestinal disease remission and to ensure the resolution of debilitating skin lesions.
Subject(s)
Inflammatory Bowel Diseases , Psoriasis , Skin Diseases , Humans , Inflammatory Bowel Diseases/epidemiology , Infliximab/therapeutic use , Psoriasis/drug therapy , Psoriasis/epidemiology , Skin Diseases/chemically induced , Tumor Necrosis Factor Inhibitors/adverse effects , Tumor Necrosis Factor-alphaSubject(s)
Colitis, Ulcerative , Colitis, Ulcerative/diagnosis , Colitis, Ulcerative/drug therapy , Humans , Indans , OxadiazolesABSTRACT
The interleukin-6 family cytokine, oncostatin-M (OSM) has been associated with response to tumor necrosis factor-α antagonists (anti-TNFs) in small cohorts of patients with inflammatory bowel disease (IBD). We aimed to evaluate the association between plasma OSM concentrations and response to anti-TNFs (infliximab and adalimumab) in both ulcerative colitis (UC) and Crohn's disease (CD). A retrospective cohort study was conducted in patients with IBD with a history of anti-TNF exposure. Blood samples, collected prior to anti-TNF exposure, were analyzed by enzyme-linked immunosorbent assay for the presence and quantity of OSM. Clinical remission was assessed at 1-year post anti-TNF exposure in addition to the occurrence of surgery, hospitalization, corticosteroid use, and adverse drug events. Lastly the threshold OSM plasma concentration associated with anti-TNF non-response was assessed by receiver operator characteristic (ROC) curve analysis. Patients with IBD (CD, n = 82; UC, n = 40) were assessed. In both UC and CD, mean pre-treatment OSM concentrations were significantly lower in those who achieved clinical remission at 1-year (p < 0.0001). A threshold plasma OSM concentration of 168.7 pg/ml and 233.6 pg/ml respectively separated those who achieved clinical remission at 1-year on an anti-TNF from those who did not in CD and UC respectively (CD: area under the receiver operator characteristic curve, AUROC = 0.880, 95% CI 0.79-0.96; UC: AUROC = 0.938, 95% CI 0.87-1.00). High OSM concentrations were associated with anti-TNF discontinuation and use of rescue steroids in CD and UC. High pre-treatment OSM concentrations identify IBD patients at-risk of anti-TNF non-response at 1-year as well as other deleterious clinical outcomes.
Subject(s)
Inflammatory Bowel Diseases/blood , Inflammatory Bowel Diseases/drug therapy , Oncostatin M/blood , Tumor Necrosis Factor Inhibitors/therapeutic use , Adolescent , Adult , Aged , Biomarkers/blood , Female , Humans , Male , Middle Aged , Retrospective Studies , Young AdultABSTRACT
BACKGROUND: Etrolizumab is a gut-targeted anti-ß7 integrin monoclonal antibody. In a previous phase 2 induction study, etrolizumab significantly improved clinical remission versus placebo in patients with moderately to severely active ulcerative colitis. We aimed to evaluate the efficacy and safety of etrolizumab for maintenance of remission in patients with moderately to severely active ulcerative colitis. METHODS: We conducted a randomised, placebo-controlled, double-blind, phase 3 study (LAUREL) across 111 treatment centres worldwide. We included adults (age 18-80 years) with moderately to severely active ulcerative colitis (Mayo Clinic total score [MCS] of 6-12 with an endoscopic subscore of ≥2, a rectal bleeding subscore of ≥1, and a stool frequency subscore of ≥1) who were naive to tumour necrosis factor inhibitors. Patients were required to have had an established diagnosis of ulcerative colitis for at least 3 months, corroborated by both clinical and endoscopic evidence, and evidence of disease extending at least 20 cm from the anal verge. During open-label induction, participants received subcutaneous etrolizumab 105 mg once every 4 weeks. Participants who had clinical response at week 10 (MCS with ≥3-point decrease and ≥30% reduction from baseline, plus ≥1-point decrease in rectal bleeding subscore or absolute rectal bleeding score of 0 or 1) proceeded into the double-blind maintenance phase and were randomly assigned (1:1) to receive subcutaneous etrolizumab 105 mg once every 4 weeks or matched placebo until week 62. Randomisation was stratified by baseline concomitant treatment with corticosteroids, treatment with immunosuppressants, baseline disease activity, and week 10 remission status. All participants and study site personnel were masked to treatment assignment. The primary endpoint was remission at week 62 (MCS ≤2, with individual subscores ≤1, and rectal bleeding subscore of 0) among patients with a clinical response at week 10, measured in the modified intention-to-treat population (all randomised patients who received at least one dose of study drug). This trial is registered with ClinicalTrials.gov, NCT02165215, and is now closed to recruitment. FINDINGS: Between Aug 12, 2014, and June 4, 2020, 658 patients were screened for eligibility and 359 were enrolled into the induction phase. 214 (60%) patients had a clinical response at week 10 and were randomly assigned to receive etrolizumab (n=108) or placebo (n=106) in the maintenance phase. 80 (74%) patients in the etrolizumab group and 42 (40%) in the placebo group completed the study through week 62. Four patients in the placebo group did not receive study treatment and were excluded from the analyses. At week 62, 32 (29·6%) of 108 patients in the etrolizumab group and 21 (20·6%) of 102 in the placebo group were in remission (adjusted treatment difference 7·7% [95% CI -4·2 to 19·2]; p=0·19). A greater proportion of patients reported one or more adverse events in the placebo group (82 [80%] of 102) than in the etrolizumab group (70 [65%] of 108); the most common adverse event in both groups was ulcerative colitis (16 [15%] patients in the etrolizumab group and 37 [36%] in the placebo group). Ten (9%) patients in the etrolizumab group and eight (8%) in the placebo group reported one or more serious adverse events. No deaths were reported in either treatment group. INTERPRETATION: No significant differences were observed between maintenance etrolizumab and placebo in the primary endpoint of remission at week 62 among patients who had a clinical response at week 10. Etrolizumab was well tolerated in this population and no new safety signals were identified. FUNDING: F Hoffmann-La Roche.
Subject(s)
Antibodies, Monoclonal, Humanized/therapeutic use , Colitis, Ulcerative/drug therapy , Gastrointestinal Agents/therapeutic use , Adolescent , Adult , Aged , Antibodies, Monoclonal, Humanized/adverse effects , Colitis, Ulcerative/chemically induced , Colitis, Ulcerative/diagnostic imaging , Colonoscopy , Double-Blind Method , Female , Gastrointestinal Agents/adverse effects , Humans , Maintenance Chemotherapy , Male , Middle Aged , Remission Induction , Severity of Illness Index , Symptom Flare Up , Young AdultABSTRACT
BACKGROUND: The lack of standardized methods for clinical trial design and disease activity assessment has contributed to an absence of approved medical therapies for the prevention of postoperative Crohn's disease (CD). We developed recommendations for regulatory trial design for this indication and for endoscopic assessment of postoperative CD activity. METHODS: An international panel of 19 gastroenterologists was assembled. Modified Research and Development/University of California Los Angeles methodology was used to rate the appropriateness of 196 statements using a 9-point Likert scale in 2 rounds of voting. Results were reviewed and discussed between rounds. RESULTS: Inclusion of patients with a history of completely resected ileocolonic CD in regulatory clinical trials for the prevention of postoperative recurrence was appropriate. Given the absence of approved medical therapies, a placebo-controlled design with a primary end point of endoscopic remission at 52 weeks was appropriate for drug development for this indication; however, there was uncertainty regarding the appropriateness of a coprimary end point of symptomatic and endoscopic remission and the use of currently available patient-reported outcome measures. The modified Rutgeerts Score, endoscopic assessment of the anastomosis, and a minimum of 5cm of neoterminal ileum were also appropriate; although the appropriateness of other indices including the Simple Endoscopic Score for CD for endoscopic assessment of postoperative CD activity was uncertain. CONCLUSIONS: A framework for regulatory trial design for the prevention of postoperative CD recurrence and endoscopic assessment of disease activity has been developed. Research to empirically validate end points for these trials is needed.
Subject(s)
Crohn Disease , Anastomosis, Surgical , Clinical Trials as Topic , Crohn Disease/diagnosis , Crohn Disease/surgery , Endoscopy , Humans , Ileum/surgery , RecurrenceABSTRACT
BACKGROUND AND AIMS: The value of ustekinumab (UST) therapeutic drug monitoring (TDM) in clinical practice remains unclear. This study examined the impact of UST TDM on clinical decision making in patients with Crohn's disease (CD). METHODS: A total of 110 consecutive UST-treated CD patients were enrolled in this multicenter, single-arm cross-sectional study. During a single study visit, clinical decisions, disease characteristics, and serum and fecal samples were obtained. The primary outcome was congruency of the actual and two hypothetical clinical decisions based on provision of UST TDM (with and without fecal calprotectin [FCP]) to participating clinicians. Decisions were compared against those of a review panel. A sub-study retrospectively measured the associations of clinical outcomes at the next follow-up visit with serum UST concentration [UST]. RESULTS: No differences in the pattern of decisions by clinicians were observed before and after provision of UST TDM (P = 1.0) or UST TDM + FCP (P = 0.86). However, 39% (TDM) and 50% (TDM + FCP) of hypothetical decisions differed from the initial decisions. The review panel's decisions differed with the addition of TDM + FCP (P = 0.0006), but not TDM alone (P = 0.16). The sub-study (n = 53) failed to detect an association between therapeutic serum [UST] at the initial study visit and clinical outcomes at the next visit. CONCLUSIONS: In consecutive CD patients treated with UST, the addition of TDM into routine clinical practice did not significantly impact clinical decisions and there was no association between short-term clinical outcomes and serum [UST]. Further studies are warranted before clinicians routinely implement UST TDM into clinical practice.