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Dive into the research topics where Max Leenders is active.

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Featured researches published by Max Leenders.


Gut | 2014

Healthcare costs of inflammatory bowel disease have shifted from hospitalisation and surgery towards anti-TNFα therapy: results from the COIN study.

Mirthe E. van der Valk; Marie-Josée J. Mangen; Max Leenders; Gerard Dijkstra; Ad A. van Bodegraven; Herma H. Fidder; Dirk J. de Jong; Marieke Pierik; C. Janneke van der Woude; Mariëlle Romberg-Camps; Cees H. Clemens; Jeroen M. Jansen; Nofel Mahmmod; Paul C. van de Meeberg; Andrea E. van der Meulen-de Jong; Cyriel Y. Ponsioen; Clemens J. M. Bolwerk; J. Reinoud Vermeijden; Peter D. Siersema; Martijn G. van Oijen; Bas Oldenburg

Objective The introduction of anti tumour necrosis factor-α (anti-TNFα) therapy might impact healthcare expenditures, but there are limited data regarding the costs of inflammatory bowel diseases (IBD) following the introduction of these drugs. We aimed to assess the healthcare costs and productivity losses in a large cohort of IBD patients. Design Crohns disease (CD) and ulcerative colitis (UC) patients from seven university hospitals and seven general hospitals were invited to fill-out a web-based questionnaire. Cost items were derived from a 3 month follow-up questionnaire and categorised in outpatient clinic, diagnostics, medication, surgery and hospitalisation. Productivity losses included sick leave of paid and unpaid work. Costs were expressed as mean 3-month costs per patients with a 95% CI obtained using non-parametric bootstrapping. Results A total of 1315 CD patients and 937 UC patients were included. Healthcare costs were almost three times higher in CD as compared with UC, €1625 (95% CI €1476 to €1775) versus €595 (95% CI €505 to €685), respectively (p<0.01). Anti-TNFα use was the main costs driver, accounting for 64% and 31% of the total cost in CD and UC. Hospitalisation and surgery together accounted for 19% and <1% of the healthcare costs in CD and 23% and 1% in UC, respectively. Productivity losses accounted for 16% and 39% of the total costs in CD and UC. Conclusions We showed that healthcare costs are mainly driven by medication costs, most importantly by anti-TNFα therapy. Hospitalisation and surgery accounted only for a minor part of the healthcare costs.


American Journal of Epidemiology | 2013

Fruit and Vegetable Consumption and Mortality European Prospective Investigation Into Cancer and Nutrition

Max Leenders; Ivonne Sluijs; Martine M. Ros; Hendriek C. Boshuizen; Peter D. Siersema; Pietro Ferrari; Cornelia Weikert; Anne Tjønneland; Anja Olsen; Marie-Christine Boutron-Ruault; F. Clavel-Chapelon; Laura Nailler; Birgit Teucher; Kuanrong Li; Heiner Boeing; Manuela M. Bergmann; Antonia Trichopoulou; Pagona Lagiou; Dimitrios Trichopoulos; Domenico Palli; Valeria Pala; Salvatore Panico; Rosario Tumino; Carlotta Sacerdote; Petra H.M. Peeters; Carla H. van Gils; Eiliv Lund; Dagrun Engeset; Maria Luisa Redondo; Antonio Agudo

In this study, the relation between fruit and vegetable consumption and mortality was investigated within the European Prospective Investigation Into Cancer and Nutrition. Survival analyses were performed, including 451,151 participants from 10 European countries, recruited between 1992 and 2000 and followed until 2010. Hazard ratios, rate advancement periods, and preventable proportions to respectively compare risk of death between quartiles of consumption, to estimate the period by which the risk of death was postponed among high consumers, and to estimate proportions of deaths that could be prevented if all participants would shift their consumption 1 quartile upward. Consumption of fruits and vegetables was inversely associated with all-cause mortality (for the highest quartile, hazard ratio = 0.90, 95% confidence interval (CI): 0.86, 0.94), with a rate advancement period of 1.12 years (95% CI: 0.70, 1.54), and with a preventable proportion of 2.95%. This association was driven mainly by cardiovascular disease mortality (for the highest quartile, hazard ratio = 0.85, 95% CI: 0.77, 0.93). Stronger inverse associations were observed for participants with high alcohol consumption or high body mass index and suggested in smokers. Inverse associations were stronger for raw than for cooked vegetable consumption. These results support the evidence that fruit and vegetable consumption is associated with a lower risk of death.


Endoscopy | 2014

Local recurrence after endoscopic mucosal resection of nonpedunculated colorectal lesions: systematic review and meta-analysis.

Tim D. Belderbos; Max Leenders; Leon M. Moons; Peter D. Siersema

BACKGROUND AND STUDY AIMS Local recurrence has been observed after endoscopic mucosal resection (EMR) of nonpedunculated colorectal lesions. The indications for follow-up colonoscopy and the optimal time interval are currently unclear. The aims of this systematic review were to assess the frequency of local recurrence after EMR, to identify risk factors for recurrence, and to provide follow-up recommendations. METHODS A literature search was performed in PubMed, EMBASE, and the Cochrane Library. EMR was defined as endoscopic snare resection after submucosal fluid injection for removal of nonpedunculated adenomas and early carcinomas. Local recurrence was subdivided into early recurrence (detected at the first follow-up colonoscopy) and late recurrence (detected after ≥ 1 previous normal colonoscopy). A random effects meta-analysis was performed to calculate the pooled estimate of risk of recurrence. RESULTS A total of 33 studies were included. The mean recurrence risk after EMR was 15 % (95 % confidence interval [CI] 12 % - 19 %). Recurrence risk was higher after piecemeal resection (20 %; 95 %CI 16 % - 25 %) than after en bloc resection (3 %; 95 %CI 2 % - 5 %; P < 0.0001). In 15 studies that differentiated between early and late recurrences, 152/173 recurrences (88 %) occurred early. In four studies with follow-up at 3, 6, and ≥ 12 months, 19/25 (76 %) recurrences were detected at 3 months, increasing to 24 (96 %) at 6 months. In multivariable analysis, only piecemeal resection was associated with recurrence (3 of 3 studies). CONCLUSION Local recurrence after EMR of nonpedunculated colorectal lesions occurs in 3 % of en bloc resections and 20 % of piecemeal resections. Piecemeal resection was the only independent risk factor for recurrence. As more than 90 % of recurrences are detected at 6 months after EMR, we propose that 6 months is the optimal initial follow-up interval.


The American Journal of Gastroenterology | 2014

Surveillance of Barrett's esophagus and mortality from esophageal adenocarcinoma: a population-based cohort study.

Romy E. Verbeek; Max Leenders; Fiebo J. ten Kate; Richard van Hillegersberg; Frank P. Vleggaar; Jantine W. van Baal; Martijn G. van Oijen; Peter D. Siersema

OBJECTIVES:Barretts esophagus (BE) is associated with an increased risk of developing esophageal adenocarcinoma (EAC). Patients with a known diagnosis of BE are usually advised to participate in an endoscopic surveillance program, but its clinical value is unproven. Our objective was to compare patients participating in a surveillance program for BE before EAC diagnosis with those not participating in such a program, and to determine predictive factors for mortality from EAC.METHODS:All patients diagnosed with EAC between 1999 and 2009 were identified in the nationwide Netherlands Cancer Registry. These data were linked to Pathologisch-Anatomisch Landelijk Geautomatiseerd Archief, the Dutch Pathology Registry. Prior surveillance was evaluated, and multivariable Cox proportional hazards regression analysis was performed to identify predictors for all-cause mortality at 2-year and 5-year follow-up.RESULTS:In total, 9,780 EAC patients were included. Of these, 791 (8%) patients were known with a prior diagnosis of BE, of which 452 (57%) patients participated in an adequate endoscopic surveillance program, 120 (15%) patients in an inadequate program, and 219 (28%) patients had a prior BE diagnosis without participating. Two-year (and five-year) mortality rates were lower in patients undergoing adequate surveillance (adjusted hazard ratio (HR)=0.79, 95% confidence interval (CI)=0.64–0.92) when compared with patients with a prior BE diagnosis who were not participating. Other factors associated with lower mortality from EAC were lower tumor stage (stage I vs. IV, HR=0.19, 95% CI=0.16–0.23) and combining surgery with neoadjuvant chemo/radiotherapy (HR=0.66, 95% CI=0.58–0.76).CONCLUSIONS:Participation in a surveillance program for BE, but only if adequately performed, reduces mortality from EAC. Nevertheless, it remains to be determined whether such a program is cost-effective, as more than 90% of all EAC patients were not known to have BE before diagnosis.


The American Journal of Clinical Nutrition | 2012

Dietary flavonoid and lignan intake and gastric adenocarcinoma risk in the European Prospective Investigation into Cancer and Nutrition (EPIC) study

Raul Zamora-Ros; Antonio Agudo; Leila Lujan-Barroso; Isabelle Romieu; Pietro Ferrari; Viktoria Knaze; H. Bas Bueno-de-Mesquita; Max Leenders; Ruth C. Travis; Carmen Navarro; Emilio Sánchez-Cantalejo; Nadia Slimani; Augustin Scalbert; Veronika Fedirko; Anette Hjartåker; Dagrun Engeset; Guri Skeie; Heiner Boeing; Jana Förster; Kuanrong Li; Birgit Teucher; Claudia Agnoli; Rosario Tumino; Amalia Mattiello; Calogero Saieva; Ingegerd Johansson; Roger Stenling; Maria Luisa Redondo; Peter Wallström; Ulrika Ericson

BACKGROUND Several experimental studies have suggested potential anticarcinogenic effects of flavonoids, although epidemiologic evidence for the impact of dietary flavonoids on risk of gastric cancer (GC) is limited. OBJECTIVE We investigated the association between intake of dietary flavonoids and lignans and incident GC. DESIGN The study followed 477,312 subjects (29.8% men) aged 35-70 y from 10 European countries who participated in the European Prospective Investigation into Cancer and Nutrition (EPIC) study. Validated dietary questionnaires and lifestyle information were collected at baseline. A food-composition database on flavonoids and lignans was compiled by using data from USDA and Phenol-Explorer databases. RESULTS During an average follow-up of 11 y, 683 incident GC cases (57.8% men) were mostly validated by a panel of pathologists and used in this analysis. We observed a significant inverse association between total flavonoid intake and GC risk in women (HR: 0.81; 95% CI: 0.70, 0.94; for the continuous variable after log₂ transformation) but not in men (HR: 0.97; 95% CI: 0.85, 1.09). In women, significant inverse associations with GC risk were also observed for intakes of some flavonoid subgroups (anthocyanidins, flavonols, flavones, and flavanols), particularly with intestinal type tumors for total flavonoid and flavanol intakes (P-heterogeneity < 0.1). After stratification by smoking status and sex, there was no significant heterogeneity in these associations between ever- and never-smokers. CONCLUSION Total dietary flavonoid intake is associated with a significant reduction in the risk of GC in women.


Gastroenterology | 2015

Cost Efficacy of Metal Stents for Palliation of Extrahepatic Bile Duct Obstruction in a Randomized Controlled Trial

Daisy Walter; Petra G. Van Boeckel; Marcel J. M. Groenen; Bas L. Weusten; Ben J. Witteman; Gi Tan; Menno A. Brink; Jan Nicolai; Adriaan C. Tan; Joyce Alderliesten; Niels G. Venneman; Wim Laleman; Jeroen M. Jansen; Alexander Bodelier; Frank Wolters; Laurens A. van der Waaij; Ronald Breumelhof; Frank T.M. Peters; Robbert C.H. Scheffer; Max Leenders; Meike M. Hirdes; Ewout W. Steyerberg; Frank P. Vleggaar; Peter D. Siersema

BACKGROUND & AIMS Endoscopic stents are placed for palliation of extrahepatic bile duct obstruction. Although self-expandable metal stents (SEMS) remain patent longer than plastic stents, they are more expensive. We aimed to evaluate which type of stent (plastic, uncovered SEMS [uSEMS], or partially covered SEMS [pcSEMS]) is the most effective and we assessed costs. METHODS We performed a multicenter randomized trial in 219 patients at 18 hospitals in The Netherlands from February 2008 through February 2013. Patients were assigned randomly for placement of a plastic stent (n = 73), uSEMS (n = 75), or pcSEMS (n = 71) during endoscopic retrograde cholangiopancreatography. Patients were followed up for up to 1 year. Researchers were not blinded to groups. The main study end points included functional stent time and costs. RESULTS The mean functional stent times were 172 days for plastic stents, 288 days for uSEMS, and 299 days for pcSEMS (P < .005 for uSEMS and pcSEMS vs plastic). The initial placement of plastic stents (€1042 or


Journal of the National Cancer Institute | 2014

Plasma Alkylresorcinols, Biomarkers of Whole-Grain Wheat and Rye Intake, and Incidence of Colorectal Cancer

Cecilie Kyrø; Anja Olsen; Rikard Landberg; Guri Skeie; Steffen Loft; Per Åman; Max Leenders; Vincent K. Dik; Peter D. Siersema; Tobias Pischon; Jane Christensen; Kim Overvad; Marie-Christine Boutron-Ruault; Guy Fagherazzi; Vanessa Cottet; Tilman Kühn; Jenny Chang-Claude; Heiner Boeing; Antonia Trichopoulou; Christina Bamia; Dimitrios Trichopoulos; Domenico Palli; Vittorio Krogh; Rosario Tumino; Paolo Vineis; Salvatore Panico; Petra H.M. Peeters; Elisabete Weiderpass; Toril Bakken; Lene Angell Åsli

1106) cost significantly less than placement of SEMS (€1973 or


Clinical Gastroenterology and Hepatology | 2013

Endoscopic Corticosteroid Injections Do Not Reduce Dysphagia After Endoscopic Dilation Therapy in Patients With Benign Esophagogastric Anastomotic Strictures

Meike M. Hirdes; Jeanin E. van Hooft; Jan J. Koornstra; Robin Timmer; Max Leenders; Rinse K. Weersma; Bas L. Weusten; Richard van Hillegersberg; Mark I. van Berge Henegouwen; John Plukker; Renee Wiezer; J. J. G. H. M. Bergman; Frank P. Vleggaar; Paul Fockens; Peter D. Siersema

2094) (P = .001). However, the total cost per patient at the end of the follow-up period did not differ significantly between plastic stents (€7320 or


Journal of Crohns & Colitis | 2014

Risk factors of work disability in patients with inflammatory bowel disease - A Dutch nationwide web-based survey: Work disability in inflammatory bowel disease.

M. Van der Valk; Marie-Josée J. Mangen; Max Leenders; Gerard Dijkstra; A.A. van Bodegraven; Herma H. Fidder; D.J. de Jong; Marieke Pierik; C.J. van der Woude; Mariëlle Romberg-Camps; Cees H. Clemens; J.B.M.J. Jansen; Nofel Mahmmod; P.C. van de Meeberg; A.E. van der Meulen-Jong; Cyriel Y. Ponsioen; Clemens J. M. Bolwerk; J.R. Vermeijden; Peter D. Siersema; M.G.H. van Oijen; Bas Oldenburg

7770) and SEMS (€6932 or


International Journal of Cancer | 2014

Plasma and dietary carotenoids and vitamins A, C and E and risk of colon and rectal cancer in the European Prospective Investigation into Cancer and Nutrition.

Max Leenders; Anke M. Leufkens; Peter D. Siersema; Fränzel J.B. Van Duijnhoven; Alina Vrieling; Paul J.M. Hulshof; Carla H. van Gils; Kim Overvad; Nina Roswall; Cecilie Kyrø; Marie-Christine Boutron-Ruault; Guy Fagerhazzi; Claire Cadeau; Tilman Kühn; Theron Johnson; Heiner Boeing; Krasimira Aleksandrova; Antonia Trichopoulou; Eleni Klinaki; Anna Androulidaki; Domenico Palli; Sara Grioni; Carlotta Sacerdote; Rosario Tumino; Salvatore Panico; Marije F. Bakker; Guri Skeie; Elisabete Weiderpass; Paula Jakszyn; Aurelio Barricarte

7356) (P = .61). Furthermore, in patients with short survival times (≤3 mo) or metastatic disease, the total cost per patient did not differ between plastic stents and SEMS. No differences in costs were found between pcSEMS and uSEMS. CONCLUSIONS Although placement of SEMS (uncovered or partially covered) for palliation of extrahepatic bile duct obstruction initially is more expensive than placement of plastic stents, SEMS have longer functional time. The total costs after 1 year do not differ significantly with stent type. Dutch Clinical Trial Registration no: NTR1361.

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Peter D. Siersema

Radboud University Nijmegen

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Gerard Dijkstra

University Medical Center Groningen

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Nofel Mahmmod

University Medical Center Groningen

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Dirk J. de Jong

Radboud University Nijmegen

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