Proactive Metabolite Testing in Patients on Thiopurine May Yield Long-Term Clinical Benefits in Inflammatory Bowel Disease.

BACKGROUND: The thiopurine medications are well established in the treatment of inflammatory bowel disease (IBD). There is significant variation in levels of toxic and therapeutic metabolites. Current data from small or short-term studies support therapeutic drug monitoring (TDM) in assessing azathioprine (AZA) and 6-mercaptopurine (6MP). TDM of thiopurines involves measurement and interpretation of metabolites 6-TGN and 6-MMPR. AIMS: This study aimed to assess long-cterm outcomes of patients on thiopurines following therapeutic drug monitoring. METHODS: A multicenter retrospective observational study of outcomes post thiopurine TDM was conducted. Demographics, disease characteristics, physician global assessment, IBD therapy at baseline TDM and again at 12 months were collected. Clinical outcomes were analyzed according to TDM result, and indication for TDM including proactive and other indications. RESULTS: The study included 541 patients. Only 39% of patients had appropriate dosing of thiopurines. AZA/6MP TDM informed a management change in 61.9%, and enabled 88.8% of the cohort to continue AZA/6MP following TDM. At 12 months following TDM the majority (74.1%) of the cohort remained on AZA/6MP. Clinical remission was higher at 12-months following thiopurines TDM (68%) compared to baseline (37%), including proactive TDM. Post TDM, 13.0% of patients were identified as shunters and commenced on thiopurine-allopurinol co-therapy. CONCLUSION: Thiopurine TDM resulted in a change in management for the majority of patients. Post TDM significantly more patients were in remission. TDM allowed the identification of non-adherence and shunters who, without intervention, would not reach therapeutic drug levels. Proactive TDM allowed identification and management of inappropriate dosing, and was associated with increased levels of clinical remission.

Visceral Adipose Tissue Is Associated With Stricturing Crohn's Disease Behavior, Fecal Calprotectin, and Quality of Life.

BACKGROUND: Visceral adipose tissue (VAT) has been proposed to play a pathogenic role in Crohn's disease (CD); however, prospective clinical data are lacking. The aim was to evaluate whether VAT, beyond body mass index (BMI), is associated with CD behavior, disease activity, quality of life (QoL), or outcomes. METHODS: Body composition data and clinical, anthropometric, disease activity (fecal calprotectin [FC]), and QoL scores were gathered prospectively on adults with CD at 0, 12, and 24 months. BMI and, VAT metrics (visceral adipose tissue volume [cm3]/height [m2] index and VAT:subcutaneous adipose tissue [SAT] ratio) were calculated. Inflammatory bowel disease-related surgery and hospitalization were recorded over extended follow-up (median, 51 months). Multivariable linear mixed effects and logistic regression analyses were performed. RESULTS: Ninety-seven participants were assessed at baseline (55% male; median age, 31 years), 84 at 12 months, and 72 at 24 months. VAT:SAT was positively associated with stricturing disease behavior (log odds ratio [OR], 1.7; 95% confidence interval [CI], 0.32 to 3; P = 0.01) and elevated FC in patients with ileocolonic disease (ß, 1.3; 95% CI, 0.32 to 2.3; P = 0.01). VAT:SAT was associated with lower QoL, particularly in those with ileal disease (ß, -12; 95% CI, -19 to -4.5; P = 0.05). However, no prospective associations were observed between serial VAT measurements and time to surgery or hospitalization. No correlations were found between BMI and disease behavior, activity, or QoL. CONCLUSIONS: VAT:SAT, rather than BMI, is associated with stricturing CD behavior, elevated FC, and reduced QoL in a disease distribution-dependent manner. Further studies are required to substantiate the role of VAT as a useful biomarker in CD.

Obesity in Inflammatory Bowel Disease: Gains in Adiposity despite High Prevalence of Myopenia and Osteopenia.

BACKGROUND: Rising rates of obesity have been reported in patients with inflammatory bowel disease (IBD); however, prospective data is lacking. The aim of this study is to prospectively evaluate body composition in adults with IBD over 24 months. METHODS: Whole body dual energy X-ray absorptiometry (DXA) data was performed at 0 months, 12 months, and 24 months. Bone mineral density (BMD), fat mass index (FMI (kg)/height (m²)), appendicular skeletal muscle index (ASMI (kg)/height (m²)), visceral adipose tissue and the visceral adipose height index (VHI, VAT area (cm³)/height (m²)), and clinical and anthropometric assessments were performed at each time point. Multivariable linear mixed effects regression analyses were performed. RESULTS: Initially, 154 participants were assessed at baseline (70% Crohn's disease, 55% male, median age 31 years), of whom 129 underwent repeated DXA at 12 months, and 110 underwent repeated DXA at 24 months. Amongst those undergoing repeated DXA, their body mass index (BMI) significantly increased over time, such that by 24 months, 62% of patients were overweight or obese (annual change BMI ß = 0.43, 95%CI = [0.18, 0.67], p = 0.0006). Gains in BMI related to increases in both FMI and VHI (ß = 0.33, 95%CI = [0.14, 0.53], p = 0.0007; ß = 0.08, 95%CI = [0.02, 0.13], p = 0.001; respectively), whereas ASMI decreased (ß = -0.07, 95%CI = [-0.12, -0.01], p = 0.01) with a concordant rise in rates of myopenia (OR = 3.1 95%CI = [1.2, 7.7]; p = 0.01). Rates of osteopenia and osteoporosis were high (37%), but remained unchanged over time (p = 0.23). CONCLUSION: Increasing rates of obesity in patients with IBD coincide with decreases in lean muscle mass over time, while high rates of osteopenia remain stable. These previously undocumented issues warrant attention in routine care to prevent avoidable morbidity.

Construct validation of a physical model colonoscopy simulator.

BACKGROUND: Previous studies have demonstrated the construct validity of virtual reality colonoscopy simulators by showing that they can distinguish between users according to their level of endoscopic experience. Although physical model simulators are known to simulate looping more realistically than these devices, they lack published validation evidence. OBJECTIVE: To assess the construct validity of a physical model simulator, the Kyoto Kagaku Colonoscope Training Model (Kyoto Kagaku Co. Ltd, Kyoto, Japan) and to determine its suitability for assessing the insertion skill of trainee colonoscopists. DESIGN: Validation study; 21 experienced colonoscopists and 18 novices made 2 attempts at each of 4 standard cases on the Kyoto Kagaku physical model simulator, and we compared their performance on each case. SETTING: A medical simulation center in a large tertiary hospital. MAIN OUTCOME MEASUREMENTS: Completion rates, times to cecum, and peak forces applied to the colon model. RESULTS: Compared with novices, experienced colonoscopists had significantly higher completion to cecum rates and shorter times to cecum for each of the 4 cases (all P < .005). For 2 cases, experienced colonoscopists also exerted significantly lower peak forces than did novices (both P = .01). LIMITATIONS: Two of the model's 6 "standard cases" were not included in the study. CONCLUSIONS: The 4 cases included in the study have construct validity in that they can distinguish between the performance of experienced colonoscopists and novices, reproducing experienced/novice differences found in real colonoscopy. These cases can be used to validly assess the insertion skill of colonoscopy trainees.