Michiel T.J. Bak

Mr. Michiel T.J. Bak

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Research Focus & Metrics

Academic Career Length

9Years (2018-Present)

(Calculated once Scilit publication data is synced: current year − year of first publication + 1)

Representative Publications

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1 November 2023 in American Journal of Gastroenterology
Verified
Journal Article
Open access
MBMichiel T.J. Bak
Michiel T.J. Bak
SHSebastiaan Ten Bokkel Huinink
Sebastiaan Ten Bokkel Huinink
NENicole Erler
Nicole Erler
ABAlexander G.L. Bodelier
Alexander G.L. Bodelier
GDGerard Dijkstra
Gerard Dijkstra
O(On Behalf Of The Dutch Initiative On Crohn And Colitis (Icc)
On Behalf Of The Dutch Initiative On Crohn And Colitis (Icc)
INTRODUCTION: The prognostic value of the modified Rutgeerts score (mRS) in patients with Crohn's disease (CD) needs to be further elucidated. This study assessed the prognostic value of the mRS for long-term outcomes after primary ileocecal resection in patients with CD. METHODS: Patients with CD after primary ileocecal resection with an available mRS at first postoperative ileocolonoscopy (index mRS) were retrospectively included. The primary outcome was surgical recurrence. Secondary outcomes were clinical recurrence and progression to severe endoscopic recurrence (≥i3). Cox proportional hazard models were used to assess the association between index mRS and outcomes. RESULTS: Six hundred fifty-two patients were included (mean follow-up: 6.4 years, SD: 4.6). Surgical recurrence rates were 7.7%, 5.3%, 12.9%, 19.1%, 28.8%, 47.8% for index mRS i0, i1, i2a, i2b, i3, and i4, respectively. Clinical recurrence occurred in 42.2% (i0), 53.7% (i1), 58.5% (i2a), 80.2% (i2b), 79.4% (i3), and 95.3% (i4) of patients. Progression to severe endoscopic recurrence occurred in 21.1% (i0), 33.9% (i1), 26.8% (i2a), and 33.3% (i2b) of patients. An index mRS of i2b (adjusted hazard ratio [aHR] 3.0; 1.5–5.6), i3 (aHR 4.0; 2.0–7.9) and i4 (aHR 8.0; 4.0–16.0) were associated with surgical recurrence. An index mRS of i1 (aHR 1.7; 1.2–2.4), i2a (aHR 1.7; 1.2–2.4), i2b (aHR 4.4; 3.2–6.0), i3 (aHR 3.6; 2.5–5.2), and i4 (aHR 7.3; 4.8–10.9) were associated with clinical recurrence. An index mRS of i1 (aHR 2.0; 1.1–3.7) or i2b (aHR 2.5; 1.4–4.6) was associated with progression to severe endoscopic recurrence. DISCUSSION: The increasing mRS corresponds closely with the risk of surgical and clinical recurrence. An index mRS ≥ i2b is associated with surgical recurrence, an index mRS ≥ i1 is associated with clinical recurrence, and i1 or i2b with progression to severe endoscopic recurrence. These results support tight monitoring of disease activity and treatment optimization in patients with ileal lesions and a more conservative management in patients with anastomotic lesions.

1 August 2018 in Inflammatory Bowel Diseases
Verified
Journal Article
Open access
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JHJoren R Ten Hove
Joren R Ten Hove
JBJonathan M K Bogaerts
Jonathan M K Bogaerts
MBMichiel T.J. Bak
Michiel T.J. Bak
MLMiangela M Laclé
Miangela M Laclé
VMVincent Meij
Vincent Meij
BOBas Oldenburg
Bas Oldenburg
Patients with refractory inflammatory bowel disease (IBD) might require a subtotal colectomy with construction of an ileostomy. Due to the risk of nerve damage and pelvic sepsis, the diverted rectum is often left in situ. Evidence on long-term complications of this rectal stump is limited, particularly in patients with Crohn’s disease (CD). In addition to the risk of development of neoplasia, diversion proctitis is a frequently reported rectal stump associated complication. Surprisingly, clear recommendations concerning rectal stump surveillance and timing of proctectomy are lacking. Through the use of a pathology database and a review of medical records, we established a cohort of IBD patients with a diverted rectum. Among these patients, long-term complications of the rectal stump were identified. Main endpoint was advanced neoplasia (carcinoma or high-grade dysplasia [HGD]) in the rectal stump. Risk factors for advanced neoplasia were identified using Cox regression modeling. In the second, prospective part of the study, a questionnaire was sent out to 165 patients with either a rectal stump in situ or who had undergone a proctectomy, in order to identify differences in patient-reported outcome measures associated with the excision of the rectal stump. From 530 patients with IBD and a (temporal) diversion of the rectum, we included 250 patients in whom the rectal stump was left in situ for more than 12 months. The majority of patients was female (61%) and had Crohn’s disease (67%). On follow-up (median 8 years), 8 carcinomas, 2 cases of high-grade dysplasia, and 7 cases of low-grade dysplasia were found with incidence rates of 3.9 and 8.5 per 1000 patient-years of follow-up for cancer and all neoplasia, respectively. The 8 cases of rectal stump cancer (RSC) were diagnosed after a median of 15 years after colectomy. A history of colorectal neoplasia was associated with advanced rectal stump neoplasia. Out of 191 patients with endoscopic follow-up, rectal stump inflammation occurred in 161 (88.5%) patients. Results of the questionnaire did not show a significant difference in quality of life between patients with and patients without a rectal stump, although the latter group reported significantly more sexual and urinary symptoms than patients with a rectal stump in situ. The majority of rectal stump patients reported rectal blood loss, but 65.5% of them were not or barely limited in daily life by their rectal stumprelated problems. Rectal stump cancer has a low incidence rate, with patients with a history of colonic neoplasia carrying the highest risk of developing this severe complication. We observed no significant differences in quality of life between rectal stump and postproctectomy patients, but proctectomy surgery is associated with sexual and urinary complications.

9 December 2022 in Gastrointestinal Endoscopy
Verified
Journal Article
Open access
MBMichiel T.J. Bak
Michiel T.J. Bak
EAEduardo Albéniz
Eduardo Albéniz
JEJames E. East
James E. East
NCNayantara Coelho-Prabhu
Nayantara Coelho-Prabhu
NSNoriko Suzuki
Noriko Suzuki
BOBas Oldenburg
Bas Oldenburg
Current guidelines recommend endoscopic resection of visible and endoscopically resectable colorectal colitis-associated neoplasia (CAN) in patients with inflammatory bowel disease (IBD). However, patients with high-risk CAN (HR-CAN) are often not amenable to conventional resection techniques, and a consensus approach for the endoscopic management of these lesions is presently lacking. This Delphi study aims to reach consensus among experts on the endoscopic management of these lesions. A 3-round modified Delphi process was conducted to reach consensus among worldwide IBD and/or endoscopy experts (n = 18) from 3 continents. Consensus was considered if ≥75% agreed or disagreed. Quality of evidence was assessed by the criteria of the Cochrane Collaboration group. Consensus was reached on all statements (n = 14). Experts agreed on a definition for CAN and HR-CAN. Consensus was reached on the examination of the colon with enhanced endoscopic imaging before resection, the endoscopic resectability of an HR-CAN lesion, and endoscopic assessment and standard report of CAN lesions. In addition, experts agreed on type of resections of HR-CAN (< 20 mm, >20 mm, with or without good lifting), endoscopic success (technical success and outcomes), histologic assessment, and follow-up in HR-CAN. This is the first step in developing international consensus-based recommendations for endoscopic management of CAN and HR-CAN. Although the quality of available evidence was considered low, consensus was reached on several aspects of the management of CAN and HR-CAN. The present work and proposed standardization might benefit future studies.

17 June 2024 in Alimentary Pharmacology & Therapeutics
Verified
Journal Article
Open access
MBMichiel T.J. Bak
Michiel T.J. Bak
KDKarlijn Demers
Karlijn Demers
NHNassim Hammoudi
Nassim Hammoudi
MAMatthieu Allez
Matthieu Allez
MSMark S. Silverberg
Mark S. Silverberg
AVAnnemarie C. de Vries
Annemarie C. de Vries
BackgroundRisk stratification for endoscopic post-operative recurrence (ePOR) in Crohn's disease (CD) is required to identify patients who would benefit most from initiation of prophylactic medication and intensive monitoring of recurrence.AimsTo assess the current evidence on patient-related, microbial, surgical and histopathological risk factors for ePOR in patients with CD after ileocolic (re-)resection.MethodsMultiple online databases (Embase, MEDLINE, Web of Science and Cochrane Library) were searched up to March 2024. Studies with reported associations of patient-related, microbial, surgical and/or histopathological factors for ePOR (i.e., Rutgeerts' score >= i2 or modified Rutgeerts' score >= i2a) were included. The risk of bias was assessed with the Newcastle-Ottawa Scale for observational cohort studies and case-control studies.ResultsIn total, 47 studies were included (four RCTs, 29 cohort studies, 12 case-control studies, one cross-sectional study and one individual participant data meta-analysis) including 6006 patients (median sample size 87 patients [interquartile range 46-170]). Risk of bias assessment revealed a poor quality in 41% of the studies. An association was reported in multiple studies of ePOR with active smoking at and post-surgery, male sex and prior bowel resection. A heterogeneous association with ePOR was reported for other risk factors included in the current guidelines (penetrating disease, perianal disease, younger age, extensive small bowel disease and presence of granulomas in the resection specimen or myenteric plexitis in the resection margin), and other patient-related, microbial, surgical and histopathological factors.ConclusionRisk factors for ePOR in international guidelines are not consistently reported as risk factors in current literature except for active smoking and prior bowel resection. To develop evidence-based, personalised strategies, large prospective studies are warranted to identify risk factors for ePOR. Validation studies of promising (bio)markers are also required. Risk factors for ePOR in international guidelines are not consistently reported as risk factors in the current literature except for active smoking and a prior bowel resection. To develop evidence-based and personalised strategies, future large prospective studies are warranted for the identification of risk factors for ePOR in patients with CD. In addition, validation studies of promising (bio)markers are required.image

8 March 2024 in Gastrointestinal Endoscopy
Verified
Journal Article
Open access
MBMichiel T.J. Bak
Michiel T.J. Bak
NHNassim Hammoudi
Nassim Hammoudi
MAMatthieu Allez
Matthieu Allez
MSMark S. Silverberg
Mark S. Silverberg
ISIsa M. Schellekens
Isa M. Schellekens
AVAnnemarie C. de Vries
Annemarie C. de Vries
The modified Rutgeerts' score (mRS) is widely used for the assessment of endoscopic postoperative recurrence (ePOR) in Crohn's disease (CD) after ileocolic resection to guide therapeutic decisions. To improve the validity and prognostic value of this endoscopic assessment, two new scores have been proposed. This study assessed the interobserver agreement of the current (mRS) and new endoscopic scores for ePOR in CD. Sixteen Dutch academic and non-academic IBD specialists assessed endoscopic videos (n=71) of postoperative CD patients (n=66) retrieved from nine Dutch centers. Each video was assessed for the degree of inflammation by four gastroenterologists using the mRS and the new proposed endoscopic score: REMIND score (separate score of anastomosis and neoterminal ileum) and updated Rutgeerts score (assessment of lesions at the anastomotic line, ileal inlet, ileal body and neoterminal ileum). In addition, lesions at the ileal body, ileal inlet, neoterminal ileum, colonic and/or ileal blind loop were separately assessed. Interobserver agreement was assessed using Fleiss' weighted kappa. Fleiss' weighted kappa for the mRS was 0.67 (95% confidence interval [CI] 0.59-0.74). The weighted kappa for the REMIND score was 0.73 (95% CI 0.65-0.80) for lesions in the neoterminal ileum and 0.46 (95% CI 0.35-0.58) for anastomotic lesions. The weighted kappa for the updated Rutgeerts' score was 0.69 (95% CI 0.62-0.77). The weighted kappa for lesions in the ileal body, ileal inlet, neoterminal ileum, colonic and ileal blind loop was 0.61 (95% CI 0.49-0.73), 0.63 (95% CI 0.54-0.72), 0.61 (95% CI 0.49-0.74), 0.83 (95% CI 0.62-1.00) and 0.68 (95% CI 0.46-0.89). The interobserver agreement of the mRS is substantial. Similarly, the interobserver agreement is substantial for the updated Rutgeerts' score. According to the REMIND score, the interobserver agreement was substantial for lesions in the neoterminal ileum, whereas only moderate for anastomotic lesions. Since therapeutic decisions in clinical practice are based on these assessments and these scores are used as outcome measure in clinical studies, further improvement of the interobserver agreement is essential.

24 January 2025 in Alimentary Pharmacology & Therapeutics
Verified
Journal Article
Open access
SHSebastiaan Ten Bokkel Huinink
Sebastiaan Ten Bokkel Huinink
MBMichiel T.J. Bak
Michiel T.J. Bak
EBEvelien M. J. Beelen
Evelien M. J. Beelen
NENicole S. Erler
Nicole S. Erler
MSMark S. Silverberg
Mark S. Silverberg
T(The Dutch Initiative On Crohn And Colitis (Icc)
The Dutch Initiative On Crohn And Colitis (Icc)
Background: The impact of prophylactic medication following ileocecal resection (ICR) for Crohn's disease (CD) merits further elucidation. Prophylactic medication following ileocecal resection (ICR) is recommended in patients with Crohn’s disease (CD), particularly in patients at increased risk of recurrence, but the impact on long‐term outcomes needs to be further elucidated.Aim: To evaluate the effect of postoperative prophylactic medication on long‐term prognosis.Methods: A retrospective cohort study was performed in patients with CD who underwent primary ICR between 2000‐2020 in the Netherlands. Patients were divided into two groups: postoperative prophylactic medication [< 12 weeks following ICR] versus no postoperative prophylactic medication. Outcomes were surgical recurrence [re‐resection for CD], severe endoscopic recurrence [modified Rutgeerts score (mRS) ≥ i3] and endoscopic or radiologic recurrence [mRS ≥ i2b or radiologic recurrence]. Inverse probability of treatment weighting [IPTW] method was used to adjust for confounding and selection bias. Survival and association between postoperative prophylactic medication and outcomes were assessed with Kaplan‐Meier analyses and Cox proportional hazard models.Results: 807 patients underwent ICR (median follow‐up 5.0 years); 36% received postoperative prophylactic medication. Surgical, severe endoscopic and endoscopic or radiologic recurrence rates were significantly lower in those who received prophylactic medication (p = 0.01; p < 0.01; p < 0.01). IPTW analysis showed a lower risk of severe endoscopic and endoscopic or radiologic recurrence in patients treated with postoperative prophylactic medication (aOR 0.64; 95% CI 0.43–0.97; aOR 0.65; 95% CI 0.47–0.91), which also was identified as a protective factor for severe endoscopic (aHR 0.5; 95% CI 0.4–0.6) and endoscopic or radiologic recurrence (aHR 0.6, 95% CI 0.5–0.7) in multivariable analysis after correction for confounding factors. A comparable protective effect of postoperative prophylactic medication was sustained in patients who underwent ileocolonoscopy <1 year postoperatively and who underwent surgery on or after 2010.Conclusions: Prophylactic medication following primary ICR significantly reduces long‐term recurrence rates in CD and was identified as a protective factor for severe endoscopic and endoscopic or radiologic recurrence.