Medicine (St Vincent's) - Research Publications
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ItemMaternal thiopurine metabolism during pregnancy in inflammatory bowel disease and clearance of thiopurine metabolites and outcomes in exposed neonates(WILEY, 2021-04)BACKGROUND: Azathioprine and mercaptopurine are considered safe during pregnancy. However, the pharmacokinetic effects of pregnancy on thiopurine metabolism are undefined. AIMS: To characterise thiopurine metabolism in pregnancy and measure infant metabolite levels and outcomes. METHODS: Women with IBD who were taking a thiopurine and pregnant or trying to conceive were recruited. Maternal thiopurine metabolites were measured pre-conception, in each trimester, at delivery and post-partum. Infant metabolite levels, full blood examination and liver function testing were performed at birth, and repeated until levels undetectable and haematological and biochemical abnormalities resolved. RESULTS: Forty patients were included with measurements on at least two occasions, and two with only mother-baby levels at delivery. The median maternal 6-TGN level dropped in the second trimester compared with post-partum (179.0 vs 323.5 pmol/8 × 108 RBCs, P < 0.001) and the median 6-MMP level increased in the second trimester compared with post-partum (1103.0 vs 329.5 pmol/8 × 108 RBCs, P < 0.01). At delivery, the median 6-TGN level was lower in infants (n = 20) than mothers (78.5 vs 217 pmol/8 × 108 RBCs) (P < 0.001). Metabolites were not detected at 6 weeks in any infants. Anaemia was not seen, but thrombocytosis and abnormal liver biochemistry were detected in 80% of infants from 6 weeks, which gradually improved. CONCLUSIONS: 6-TGN levels decrease and 6-MMP levels increase in the second trimester of pregnancy. Infants are exposed to thiopurine metabolites at low levels with clearance by 6 weeks and no anaemia. The cause of infant thrombocytosis and abnormal liver biochemistry in the absence of metabolites is unclear.
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ItemSerologic antibodies in relation to outcome in postoperative Crohn's disease(WILEY, 2017-06)BACKGROUND AND AIM: Disease recurs frequently after Crohn's disease resection. The role of serological antimicrobial antibodies in predicting recurrence or as a marker of recurrence has not been well defined. METHODS: A total of 169 patients (523 samples) were prospectively studied, with testing peri-operatively, and 6, 12 and 18 months postoperatively. Colonoscopy was performed at 18 months postoperatively. Serologic antibody presence (perinuclear anti-neutrophil cytoplasmic antibody [pANCA], anti-Saccharomyces cerevisiae antibodies [ASCA] IgA/IgG, anti-OmpC, anti-CBir1, anti-A4-Fla2, anti-Fla-X) and titer were tested. Quartile sum score (range 6-24), logistic regression analysis, and correlation with phenotype, smoking status, and endoscopic outcome were assessed. RESULTS: Patients with ≥ 2 previous resections were more likely to be anti-OmpC positive (94% vs 55%, ≥ 2 vs < 2, P = 0.001). Recurrence at 18 months was associated with anti-Fla-X positivity at baseline (49% vs 29%; positive vs negative, P = 0.033) and 12 months (52% vs 31%, P = 0.04). Patients positive (n = 28) for all four antibacterial antibodies (anti-CBir1, anti-OmpC, anti-A4-Fla2, and anti-Fla-X) at baseline were more likely to experience recurrence at 18 months than patients negative (n = 32) for all four antibodies (82% vs 18%, P = 0.034; odds ratio 6.4, 95% confidence interval 1.16-34.9). The baseline quartile sum score for all six antimicrobial antibodies was higher in patients with severe recurrence (Rutgeert's i3-i4) at 18 months, adjusted for clinical risk factors (odds ratio 1.16, 95% confidence interval 1.01-1.34, P = 0.039). Smoking affected antibody status. CONCLUSIONS: Anti-Fla-X and presence of all anti-bacterial antibodies identifies patients at higher risk of early postoperative Crohn's disease recurrence. Serologic screening pre-operatively may help identify patients at increased risk of recurrence.
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ItemThiopurine metabolite testing in inflammatory bowel disease(WILEY, 2016-03)BACKGROUND: Thiopurine use in inflammatory bowel disease (IBD) is limited by drug toxicity and lack of therapeutic efficacy. We assessed the utility of thiopurine metabolite testing and the relationship between disease activity, dose, and metabolite levels in a real world setting. METHODS: Patients identified from pathology databases (2007-2012) at two tertiary IBD centers were included if they had thiopurines for at least four weeks. Demographics, dose, test indication, clinical status, action taken, and outcome were obtained by retrospective medical record review. RESULTS: A total of 169 patients were included. 6-Thioguanine (TGN) levels were sub-therapeutic in 52%, therapeutic in 34%, and supratherapeutic in 14%. Test indication was active disease (79%), adverse effect (11%), or adherence assessment (7%). TGN trended lower in the active disease group compared to those with adverse effects (273 (+/- 23.2) versus 447 (+/- 117.7) pmol/8 × 10(8) RBC, P = 0.05). Weight-based dosing did not improve rates of therapeutic TGN levels (under-dosed 31.5% vs standard dose 35.4%), but was significantly associated with shunting toward 6-MMP (23.1% vs 6.8%, P = 0.008, OR = 4.1). Testing resulted in a change in patient treatment in 86% of patients with active disease and subtherapeutic levels and in 68% of tested patients overall. CONCLUSIONS: Metabolite testing resulted in a change in management in most patients not responding to thiopurines or experiencing adverse events. Weight-based dosing did not increase rates of therapeutic levels but was associated with increased 6MMP shunting.
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ItemMagnetic resonance enterography for predicting the clinical course of Crohn's disease strictures(WILEY, 2020-06)BACKGROUND AND AIMS: Strictures are the most common Crohn's disease complication, but their natural history is unknown. This study aimed to characterize inflammation, predict prognosis, and understand the impact of drug therapy using magnetic resonance enterography (MRE). METHODS: Patients with a stricture diagnosed on MRE over a 5-year period were reviewed for MRE disease extent and inflammation, clinical course, C-reactive protein, response to anti-TNF therapy, endoscopic dilatation, hospitalization, and surgery. RESULTS: 136 patients had 235 strictures (77, one and 59, ≥ 2 strictures). TREATMENT: 46% of patients underwent surgery after a median 6 months; median follow-up for those not requiring surgery was 41 months. Predictors of surgery: Hospitalization because of obstruction predicted subsequent surgery (OR 2.50; 95% CI 1.06-5.90) while anti-TNF therapy commenced at stricture diagnosis was associated with a reduced risk (OR 0.23; 95% CI 0.05-0.99). MRE characteristics associated with surgery were proximal bowel dilatation ≥ 30-mm diameter (OR 2.98; 95% CI 1.36-6.55), stricture bowel wall thickness ≥ 10-mm (OR 2.42; 95% CI 1.11-5.27), and stricture length > 5-cm (OR 2.56; 95% CI 1.21-5.43). 81% of patients with these three adverse MRE features required surgery versus 17% if none were present (P < 0.001). Accuracy for these three MRE variables predicting surgery was high (AUC 0.76). CONCLUSION: Magnetic resonance enterography findings in Crohn's disease strictures are highly predictive of the disease course and the need for future surgery. MRE may also identify who would benefit from treatment intensification. Anti-TNF therapy is associated with reduced risk of surgery and appears to alter the natural history of this complication.
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ItemInfliximab, adalimumab and vedolizumab concentrations across pregnancy and vedolizumab concentrations in infants following intrauterine exposure(WILEY, 2020-11)Background The impact of pregnancy on levels of biologic agents in patients with IBD is undefined and time to elimination in vedolizumab‐exposed infants is unknown. Aims To determine the effect of pregnancy on infliximab, adalimumab and vedolizumab levels and to study infant vedolizumab clearance Methods In a prospective observational study, maternal drug levels were measured pre‐conception, in each trimester, at delivery and postpartum. The association between drug levels and gestation in weeks was assessed using generalised estimating equation modelling. Infant vedolizumab levels were performed at birth (cord blood), 6 weeks and 3 months or until undetectable. Results We included 50 IBD patients (23 on infliximab, 15 on adalimumab and 12 on vedolizumab) with at least two intrapartum observations, plus 5 patients on vedolizumab with only mother and baby samples at delivery. Modelling showed no change in adalimumab levels, an increase in infliximab levels of 0.16 (95% CI 0.08‐0.24) µg/L/week (P < 0.001) and a decrease of 0.18 (95% CI: −0.33 to −0.02) µg/L/week (P = 0.03) for vedolizumab. In 17 mother‐baby pairs, median infant vedolizumab levels at birth were lower than maternal levels (P < 0.05) with an infant:maternal ratio of 0.7 (IQR 0.5‐0.9). Vedolizumab was undetectable between 15 and 16 weeks of age in all 12 infants completing follow‐up testing. Conclusions During pregnancy, adalimumab levels remain stable, while infliximab levels increase and vedolizumab levels decrease. However, the increments were small suggesting that intrapartum therapeutic drug monitoring and dose adjustment are not indicated. Unlike infliximab and adalimumab, infant vedolizumab levels are lower in cord blood than in mothers and appear to clear rapidly.
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ItemAccuracy of point-of-care intestinal ultrasound for Crohn's disease.(Wiley, 2020-08)BACKGROUND: Point-of-care ultrasound (POCUS), performed by a gastroenterologist, provides safe and convenient imaging allowing for immediate clinical decision in Crohn's disease. The minimum training required to gain competency, its accuracy and clinical utility requires evaluation. METHODS: In this pilot study, Crohn's disease activity and extent were assessed using POCUS (performed by a single gastroenterologist following the completion of 200 supervised scans), magnetic resonance enterography (MRE) and ileo-colonoscopy. The presence of complications was assessed by POCUS and MRE. Accuracy of POCUS was analysed with respect to MRE and ileo-colonoscopy. Agreement between modalities was assessed using kappa coefficient. RESULTS: Forty-two patients had a POCUS paired with MRE. Thirty-eight patients had a POCUS paired with ileo-colonoscopy. When compared to MRE, POCUS was accurate in the assessment of disease activity (sensitivity 87.5%, specificity 61.1%, ROC 0.74), extent (sensitivity 77.8%, specificity 83.3%, ROC 0.81) and complications (sensitivity 85.7%, specificity 94.3%, ROC 0.90). Agreement between POCUS and MRE was moderate (kappa estimates 0.50, P < 0.001, 0.61, P < 0.001 and 0.76, P < 0.001) for disease activity, extent and complications, respectively. When compared to ileo-colonoscopy, POCUS was accurate in the assessment of disease activity (sensitivity 72%, specificity 86%, ROC 0.79) and extent (sensitivity 85.7%, specificity 86%, ROC 0.86). For POCUS and ileo-colonoscopy, kappa estimates were 0.55, P < 0.001 for disease activity and 0.62, P < 0.001 for disease extent. CONCLUSION: POCUS performed by a gastroenterologist after completion of limited training is accurate for assessing Crohn's disease activity, extent and the presence of complications.
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ItemLong-term outcomes of perianal fistulizing Crohn's disease in the biologic era(WILEY, 2020-12-20)While the advent of biologic therapy has led to improved outcomes in perianal fistulizing Crohn's disease (pfCD), loss of response is common. Previous studies suggest that patients who achieve radiological healing (with healing of underlying tracts on magnetic resonance imaging [MRI]) have a longer duration of response. The aim of this study was to characterize MRI outcomes of pfCD at a specialist inflammatory bowel disease (IBD) unit and compare the long‐term clinical outcomes between patients achieving MRI and clinical healing.