Wim C J Hop

Erasmus MC, Rotterdam, South Holland, Netherlands

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Publications (908)4180.39 Total impact

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    Full-text · Article · Sep 2015 · Obstetric Anesthesia Digest
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    ABSTRACT: The aim of this study was to assess the effect of intravenous (IV) insulin administration in children with severe acute asthma (SAA) and hyperglycemia on IV salbutamol consumption and length of stay (LOS) in a pediatric intensive care unit (PICU). Retrospective, descriptive study of the clinical course before and after implementation of an insulin protocol for the treatment of hyperglycemia (i.e. blood glucose >8 mmol/L or 144 mg/dL, respectively) in the PICU of a tertiary care university hospital. Admissions between 1994 and 2010 were reviewed. The insulin protocol was introduced in 2006. A total of 131 pediatric patients with SAA complicated by hyperglycemia requiring IV salbutamol were included. Severity of illness before and after implementation of the insulin protocol did not significantly differ. The insulin-treated patient group had significantly higher maximum blood glucose levels and higher cumulative IV salbutamol dose than the non-treated group. There were no differences between these groups in the duration of IV salbutamol administration and LOS. In view of the lack of difference in outcomes and considering that the insulin protocol is labor-intensive, the question is whether this protocol is efficacious for the treatment of pediatric SAA associated with hyperglycemia.
    No preview · Article · May 2015 · Journal of Asthma
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    ABSTRACT: Asthma guidelines recommend monitoring of asthma control. However, in a substantial proportion of children, asthma is poorly controlled and the best monitoring strategy is not known. We studied two monitoring strategies for their ability to improve asthma outcomes in comparison with standard care (SC): web-based monthly monitoring with the (Childhood) Asthma Control Test (ACT or C-ACT) and 4-monthly monitoring of FENO. In this randomised controlled, partly blinded, parallel group multicentre trial with a 1-year follow-up, children aged 4-18 years with a doctor's diagnosis of asthma treated in seven hospitals were randomised to one of the three groups. In the web group, treatment was adapted according to ACT obtained via a website at 1-month intervals; in the FENO group according to ACT and FENO, and in the SC group according to the ACT at 4-monthly visits. The primary endpoint was the change from baseline in the proportion of symptom-free days (SFD). Two-hundred and eighty children (mean age 10.4 years, 66% boys) were included; 268 completed the study. Mean changes from baseline in SFD were similar between the groups: -2.1% (web group, n=90), +8.9% (FENO group, n=91) versus 0.15% (SC, n=87), p=0.15 and p=0.78. Daily dose of inhaled corticosteroids (ICS) decreased more in the web-based group compared with both other groups (-200 μg/day, p<0.01), while ACT and SFD remained similar. The change from baseline in SFD did not differ between monitoring strategies. With web-based ACT monitoring, ICS could be reduced substantially while control was maintained. NTR 1995. Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to http://group.bmj.com/group/rights-licensing/permissions.
    No preview · Article · Mar 2015 · Thorax
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    ABSTRACT: To investigate changes in trapped air volume and distribution over time and compare computed tomography (CT) with pulmonary function tests for determining trapped air. Thirty children contributed two CTs and pulmonary function tests over 2 years. Localized changes in trapped air on CT were assessed using image analysis software, by deforming the CT at timepoint 2 to match timepoint 1, and measuring the volume of stable (TAstable), disappeared (TAdisappeared) and new (TAnew) trapped air as a proportion of total lung volume. We used the difference between total lung capacity measured by plethysmography and helium dilution, residual volume to total lung capacity ratio, forced expiratory flow at 75% of vital capacity, and maximum mid-expiratory flow as pulmonary function test markers of trapped air. Statistical analysis included Wilcoxon's signed rank test and Spearman correlation coefficients. Median (range) age at baseline was 11.9 (5-17) years. Median (range) of trapped air was 9.5 (2-33)% at timepoint 1 and 9.0 (0-25)% at timepoint 2 (p=0.49). Median (range) TAstable, TAdisappeared and TAnew were respectively 3.0 (0-12)%, 5.0 (1-22)% and 7.0 (0-20)%. Trapped air on CT correlated statistically significantly with all pulmonary function measures (p<0.01), other than residual volume to total lung capacity ratio (p=0.37). Trapped air on CT did not significantly progress over 2 years, may have a substantial stable component, and is significantly correlated with pulmonary function markers. Copyright © 2015. Published by Elsevier Ireland Ltd.
    No preview · Article · Feb 2015 · European Journal of Radiology
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    ABSTRACT: We prospectively studied the incidence and clinical course of hypertriglyceridemia and hypercholesterolemia during very prolonged use of asparaginase or in relation to asparaginase activity levels in children with acute lymphoblastic leukemia. Also, incidence of pancreatitis, thrombosis, hyperammonemia and central neurotoxicity and their association with asparaginase activity levels were evaluated. 89 patients were treated according to Dutch Childhood Oncology Group Acute Lymphoblastic Leukemia 10 medium-risk intensification protocol, which includes 15 doses PEGasparaginase(2,500 IU/m2) for 30 weeks. Erwinia-asparaginase(20,000 IU/m2) was administered when allergy to or silent inactivation of PEGasparaginase occurred. Triglyceride/cholesterol/ammonia levels increased rapidly in children with PEGasparaginase and remained temporary elevated, but normalized after finishing the last asparaginase dose. Hypertriglyceridemia and hypercholesterolemia(grade 3/4) were found in 47% and in 25%, respectively, of PEGasparaginase-treated patients. Studying the correlations between PEGasparaginase activity levels and triglyceride levels showed the strongest correlation at week 5 (Spearman correlation coefficient=0.36, p=0.005). Children >10 years had higher triglyceride levels as compared to younger patients(<10 years) adjusted for asparaginase preparations: median 4.9 mmol/L versus 1.6 mmol/L(p<0.001). In patients receiving Erwinia-asparaginase, triglyceride levels increased in the first weeks as well, but no grade 3/4 dyslipidemia was found. Hyperammonemia(grade 3/4) was only found in Erwinia-asparaginase treated patients(9%). Thrombosis occurred in 4.5%, pancreatitis in 7 %, and central neurotoxicity in 9 % of patients using each of both agents; these toxicities were not related to asparaginase activity levels nor to triglyceride levels. Severe dyslipidemia occurred frequently, but was temporary and was not associated with relevant clinical events and therefore should not be considered a reason for asparaginase treatment modifications. Only dyslipidemia was related to asparaginase activity levels.
    Full-text · Article · Aug 2014 · Haematologica

  • No preview · Article · Jun 2014
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    ABSTRACT: The aim of this cross-sectional study was to analyze the incidence of incisional hernia after liver transplantation (LT), to determine potential risk factors for their development and to assess their impact of incisional hernia on health-related quality of life (HRQoL).Patients who underwent LT through a J-shaped incision with a minimum follow-up of 3 months were included. Follow-up was conducted at the outpatient clinic. Short form 36 (SF-36) and body image questionnaire (BIQ) were used for the assessment of HRQoL.A total of 140 patients was evaluated. The mean follow-up period was 33 (SD 20) months. Sixty patients (43%) were diagnosed with an incisional hernia. Multivariate analysis revealed surgical site infection (OR 5.27, p = 0.001), advanced age (OR 1.05, p = 0.003), and prolonged ICU stay (OR 1.54, p = 0.022) to be independent risk factors for development of incisional hernia after LT. Patients with an incisional hernia experienced significantly diminished HRQoL with respect to physical, social, and mental aspects.In conclusion, patients who undergo LT exhibit a high incidence of incisional hernia, which has a considerable impact on HRQoL. Development of incisional hernia was shown to be related to surgical site infection, advanced age and prolonged ICU stay.This article is protected by copyright. All rights reserved.
    No preview · Article · May 2014 · Clinical Transplantation
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    ABSTRACT: Background: Aim of the study was to validate commonly used bedside right-ventricular (RV) impedance parameters, which are utilized in determining heart-lung interactions during mechanical ventilation. Methods: Fifteen pigs were equally assigned to either an open or a closed pericardium group. In all animals, an inflatable vascular occluder and a flow probe were placed around the main pulmonary artery, which allowed for a gradual increase in pulmonary vascular impedance with banding of the pulmonary artery. A median sternotomy was performed for the open pericardium group, and a lateral thoracotomy was performed for the closed pericardium group. Results: In the open pericardium group, mean acceleration time (ACmean) and the slope of the pulmonary artery flow correlated significantly with Poiseuille resistance over the banding (r=0.67 and r=0.65, respectively). In the closed pericardium group, the ratio of the right to left ventricular area, eccentricity index, and tricuspid annular plane systolic excursion did not correlate with resistance over the banding, only the ACmean showed a significant correlation with resistance over the banding (r=0.88). Conclusion: ACmean is a reliable parameter of RV impedance that can be used to study the heart-lung interactions during mechanical ventilation.
    No preview · Article · Mar 2014 · Minerva anestesiologica
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    Full-text · Dataset · Feb 2014
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    ABSTRACT: Small airway obstruction is important in the pathophysiology of cystic fibrosis (CF) lung disease. Additionally, many CF patients lose lung function in the long term as a result of respiratory tract exacerbations (RTEs). No trials have been performed to optimize mucolytic therapy during a RTE. We investigated whether specifically targeting dornase alfa to the small airways improves small airway obstruction during RTEs. In a multi-center, double-blind, randomized controlled trial CF patients hospitalized for a RTE and on maintenance treatment with dornase alfa were switched to a smart nebulizer. Patients were randomized to small airway deposition (n = 19) or large airway deposition (n = 19) of dornase alfa for at least 7 days. Primary endpoint was forced expiratory flow at 75% of forced vital capacity (FEF75 ). Spirometry parameters improved significantly during admission, but the difference in mean change in FEF75 between treatment groups was not significant: 0.7 SD, P = 0.30. FEF25-75 , FEV1 , nocturnal oxygen saturation and diary symptom scores also did not differ between groups. This study did not detect a difference if inhaled dornase alfa was targeted to small versus large airways during a RTE. However, the 95% confidence interval for the change in FEF75 was wide. Further studies are needed to improve the effectiveness of RTE treatment in CF. Pediatr Pulmonol. © 2013 Wiley Periodicals, Inc.
    No preview · Article · Feb 2014 · Pediatric Pulmonology
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    T.F. Runia · W.C.J. Hop · Y.B. de Rijke · R.Q. Hintzen
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    ABSTRACT: Vitamin A is a multifunctional vitamin that can inhibit the formation of Th17 cells, which are probably involved in the development of relapses in MS. Furthermore, it promotes Treg formation. Therefore, vitamin A can be hypothesized to be lower in patients than in healthy controls, and to decrease relapse risk in relapsing-remitting MS (RRMS) patients. To compare vitamin A levels in MS patients and controls, and to investigate whether vitamin A levels are associated with relapse risk. In a case-control study all-trans-retinol levels were compared between 31 RRMS patients and 29 matched controls. In a prospective longitudinal study in 73 RRMS patients, serum samples for all-trans-retinol measurements were taken every eight weeks. Associations between all-trans-retinol concentrations and relapse rates were calculated using Poisson regression with the individual serum levels as time-dependent variable. Associations between vitamin A and vitamin D were calculated. Mean vitamin A levels were lower in patients (2.16μmol/l) than in controls (2.44μmol/l) but with borderline significance (p=0.05). In the longitudinal study, during follow-up (mean 1.7 years), 58 patients experienced a total of 139 relapses. Monthly moving averages of all-trans retinol levels were categorized into tertiles: a low (<2.9μmol/l), medium (2.9-3.7μmol/l) and high level (>3.7μmol/l). Relapse rates were not associated with serum all-trans retinol levels (p>0.2), in univariate nor in multivariate analysis. Serum concentrations of all-trans-retinol and 25-OH-vitamin D were positively correlated, although this correlation was weak (r=0.15). We did not find evidence for a role for vitamin A in the disease course of RRMS. We did find an association between vitamin A and D levels in the RRMS patients, possibly explained by dietary products that contain both fat-soluble vitamins. Copyright © 2013 The Authors. Published by Elsevier B.V. All rights reserved.
    Full-text · Article · Jan 2014 · Multiple Sclerosis and Related Disorders
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    ABSTRACT: This study prospectively analyzed the efficacy of very prolonged PEGasparaginase and Erwinia asparaginase (Erwinia-asp) courses in pediatric acute lymphoblastic leukemia (ALL) patients. Patients received 15 PEGasparaginase infusions (2,500 IU/m2 q2 weeks) in intensification after receiving native E.coli asparaginase in induction. In case of allergy to or silent inactivation of PEGasparaginase, Erwinia-asp (20,000 IU/m2 2-3 times weekly) was given. Eighty-nine patients were enrolled in the "PEGasparaginase study". Twenty(22%) of the PEGasparaginase-treated patients developed an allergy; seven (8%) showed silent inactivation. PEGasparaginase level was zero in all allergic patients (grade 1-4). Patients without hypersensitivity to PEGasparaginase had serum mean trough levels of 899 U/L. Fifty-nine patients were included in the "Erwinia-asp study", two (3%) developed an allergy and none silent inactivation. Ninety-six percent had at least one trough level ≥100 U/L. Serum asparagine level was not always completely depleted with Erwinia-asp in contrast to PEGasparaginase. Presence of asparaginase-antibodies was related to allergies and silent inactivation, but with low specificity (64%). Use of native E.coli asparaginase in induction leads to high hypersensitivity rates to PEGasparaginase in intensification. Therefore, PEGasparaginase should be used already in induction and we suggest that the dose could be lowered. Switching to Erwinia-asp leads to effective asparaginase levels in most patients. Therapeutic drug monitoring has been added to our ALL-11-protocol to individualize asparaginase therapy.
    Full-text · Dataset · Jan 2014
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    ABSTRACT: This study prospectively analyzed the efficacy of very prolonged PEGasparaginase and Erwinia-asparaginase (Erwinia-asp) courses in pediatric acute lymphoblastic leukemia (ALL) patients. Patients received 15 PEGasparaginase infusions (2,500IU/m(2) q2 weeks) in intensification after receiving native E.coli-asparaginase in induction. In case of allergy to or silent-inactivation of PEGasparaginase, Erwinia-asp(20,000IU/m(2) 2-3 times weekly) was given. Eighty-nine patients were enrolled in the "PEGasparaginase study". Twenty(22%) of the PEGasparaginase-treated patients developed an allergy; seven(8%) showed silent inactivation. PEGasparaginase level was zero in all allergic patients(grade 1-4). Patients without hypersensitivity to PEGasparaginase had serum mean trough levels of 899 U/L. Fifty-nine patients were included in the "Erwinia-asp study", two(3%) developed an allergy and none silent-inactivation. Ninety-six percent had at least one trough level ≥100 U/L. Serum asparagine level was not always completely depleted with Erwinia-asp in contrast to PEGasparaginase. Presence of asparaginase-antibodies was related to allergies and silent-inactivation, but with low specificity(64%). Use of native E.coli-asparaginase in induction leads to high hypersensitivity rates to PEGasparaginase in intensification. Therefore, PEGasparaginase should be used already in induction and we suggest that the dose could be lowered. Switching to Erwinia-asp leads to effective asparaginase levels in most patients. Therapeutic-drug-monitoring has been added to our ALL-11-protocol to individualize asparaginase therapy.
    Full-text · Article · Jan 2014 · Blood
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    Full-text · Article · Jan 2014 · Annals of Surgery
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    ABSTRACT: Prolonged prednisolone treatment for the initial episode of childhood nephrotic syndrome may reduce relapse rate, but whether this results from the increased duration of treatment or a higher cumulative dose remains unclear. We conducted a randomized, double-blind, placebo-controlled trial in 69 hospitals in The Netherlands. We randomly assigned 150 children (9 months to 17 years) presenting with nephrotic syndrome to either 3 months of prednisolone followed by 3 months of placebo (n=74) or 6 months of prednisolone (n=76), and median follow-up was 47 months. Both groups received equal cumulative doses of prednisolone (approximately 3360 mg/m(2)). Among the 126 children who started trial medication, relapses occurred in 48 (77%) of 62 patients who received 3 months of prednisolone and 51 (80%) of 64 patients who received 6 months of prednisolone. Frequent relapses, according to international criteria, occurred with similar frequency between groups as well (45% versus 50%). In addition, there were no statistically significant differences between groups with respect to the eventual initiation of prednisolone maintenance and/or other immunosuppressive therapy (50% versus 59%), steroid dependence, or adverse effects. In conclusion, in this trial, extending initial prednisolone treatment from 3 to 6 months without increasing cumulative dose did not benefit clinical outcome in children with nephrotic syndrome. Previous findings indicating that prolonged treatment regimens reduce relapses most likely resulted from increased cumulative dose rather than the treatment duration.
    No preview · Article · Dec 2013 · Journal of the American Society of Nephrology
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    ABSTRACT: To elucidate incidence and risk factors of bone mineral density and fracture risk in children with Acute Lymphoblastic Leukemia (ALL). Prospectively, cumulative fracture incidence, calculated from diagnosis until one year after cessation of treatment, was assessed in 672 patients. This fracture incidence was compared between subgroups of treatment stratification and age subgroups (Log-Rank test). Serial measurements of bone mineral density of the lumbar spine (BMDLS) were performed in 399 ALL patients using dual energy X-ray absorptiometry. We evaluated risk factors for a low BMD (multivariate regression analysis). Osteoporosis was defined as a BMDLS≤-2 SDS combined with clinical significant fractures. The 3-years cumulative fracture incidence was 17.8%. At diagnosis, mean BMDLS of ALL patients was lower than of healthy peers (mean BMDLS=-1.10 SDS, P<0.001), and remained lower during/after treatment (8months: BMDLS=-1.10 SDS, P<0.001; 24months: BMDLS=-1.27 SDS, P<0.001; 36months: BMDLS=-0.95 SDS, P<0.001). Younger age, lower weight and B-cell-immunophenotype were associated with a lower BMDLS at diagnosis. After correction for weight, height, gender and immunophenotype, stratification to the high risk (HR)-protocol arm and older age lead to a larger decline of BMDLS (HR group: β=-0.52, P<0.01; age: β=-0.16, P<0.001). Cumulative fracture incidences were not different between ALL risk groups and age groups. Patients with fractures had a lower BMDLS during treatment than those without fractures. Treatment-related bone loss was similar in patients with and without fractures (respectively: ΔBMDLS=-0.36 SDS and ΔBMDLS=-0.12 SDS; interaction group time, P=0.30). Twenty of the 399 patients (5%) met the criteria of osteoporosis. Low values of BMDLS at diagnosis and during treatment, rather than the treatment-related decline of BMDLS, determines the increased fracture risk of 17.8% in children with ALL.
    Full-text · Article · Nov 2013 · Bone
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    Full-text · Article · Nov 2013 · Pediatric Blood & Cancer
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    Dataset: JPO HADS

    Full-text · Dataset · Oct 2013
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    ABSTRACT: After a more successful treatment of pediatric cancer, the number of childhood cancer survivors is progressively increasing. Consequently, awareness of psychological late sequelae is important. The Hospital Anxiety and Depression Scale (HADS) was used as a screening tool for emotional distress in a single center cohort of 652 childhood cancer survivors (median age 23 y [range, 15 to 46 y], median follow-up time 15 y [range, 5 to 42 y]). Results were compared with a control group of 440 Dutch subjects. A higher HADS score linearly reflect a higher level of emotional distress, and a score ≥15 is indicative of clinically significant emotional distress. Mean HADS score of the childhood cancer survivors was not different from the control group (P=0.38). Survivors exposed to global central nervous system (CNS) irradiation had a significantly higher HADS score than the control group (8.3±6.6; P=0.05) as well as other survivors (P=0.01). Forty-three survivors (7%) had a HADS score ≥15. Survivors with a HADS score ≥15 were variously spread over the diagnostic-related and treatment-related subgroups. Linear regression analysis showed that high educational achievement (β=-1.28; P<0.01) and age at the time of the study (β=0.08; P=0.03) were both significantly associated with the HADS score. Emotional distress does not occur more often in childhood cancer survivors than in the normal population. No disease-related or treatment-related variable was independently associated with emotional distress.
    Full-text · Article · Oct 2013 · Journal of Pediatric Hematology/Oncology
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    ABSTRACT: Randomized studies support the closure of midline incisions with a suture length to wound length ratio (SL:WL) of more than 4, accomplished with small tissue bites and short stitch intervals to decrease the risk of incisional hernia and wound infection. We investigated practical aspects of this technique possibly hampering the introduction of this technique. Patient data, operative variables and SL:WL ratio were collected at two hospitals: Sundsvall Hospital (SH) and Erasmus University Medical Center (EMC). A structured implementation of the technique had been performed at SH but not at EMC. Personnel were interviewed by questionnaire. At each hospital, 18 closures were analyzed. Closure time was significantly longer (p = 0.023) at SH (median 18 minutes, range: 9-59) than at EMC (median 13 minutes, range: 5-23). An SL:WL ratio of more than 4 was achieved in 8 of 18 cases at EMC and in all 18 cases at SH. We conclude that calculation of an SL:WL ratio is easily performed. Suturing with the small bite-short stitch interval technique of SH required 5 minutes extra, outweighing the morbidity of incisional hernia. Without a structured implementation to suture with an SL:WL ratio of more than 4, a lower ratio is often achieved.
    No preview · Article · Sep 2013 · Surgical technology international

Publication Stats

34k Citations
4,180.39 Total Impact Points


  • 1998-2015
    • Erasmus MC
      • • Department of Biostatistics
      • • Department of Surgery
      • • Department of Radiology
      • • Department of Oncological Surgery
      Rotterdam, South Holland, Netherlands
    • Catharina Hospital
      Eindhoven, North Brabant, Netherlands
  • 2011-2013
    • Leiden University Medical Centre
      Leyden, South Holland, Netherlands
  • 1980-2013
    • Erasmus Universiteit Rotterdam
      • • Department of Obstetrics and Gynaecology
      • • Department of Epidemiology
      • • Department of Surgery
      • • Department of Pediatrics/Respiratory Medicine
      • • Department of Immunology
      • • Department of Pathology
      • • Department of Urology
      • • Department of Radiotherapy
      Rotterdam, South Holland, Netherlands
  • 2003-2011
    • Radboud University Nijmegen
      • • Medical Centre
      • • Department of Pulmonary Diseases
      Nymegen, Gelderland, Netherlands
    • George Washington University
      • Department of Pediatrics
      Washington, Washington, D.C., United States
    • Karolinska Institutet
      • Department of Oncology-Pathology
      Solna, Stockholm, Sweden
  • 2009
    • HagaZiekenhuis van Den Haag
      's-Gravenhage, South Holland, Netherlands
  • 2008
    • Sint Franciscus Gasthuis Rotterdam
      Rotterdam, South Holland, Netherlands
    • Delft University Of Technology
      • Department of Industrial Design
      Delft, South Holland, Netherlands
  • 2007
    • University Medical Center Utrecht
      • Urology
      Utrecht, Utrecht, Netherlands
  • 2005
    • Canadian Society for Epidemiology and Biostatistics 
  • 2001-2005
    • Maastricht Universitair Medisch Centrum
      Maestricht, Limburg, Netherlands
    • University of Iowa Children's Hospital
      Iowa City, Iowa, United States
  • 1994-2005
    • Het Oogziekenhuis Rotterdam
      Rotterdam, South Holland, Netherlands
  • 2004
    • St Anna's Kinderspital
      Wien, Vienna, Austria
  • 2002
    • University of Milan
      Milano, Lombardy, Italy
  • 1992-2001
    • University of Groningen
      Groningen, Groningen, Netherlands
  • 2000
    • University of California, San Francisco
      San Francisco, California, United States
    • VU University Amsterdam
      Amsterdamo, North Holland, Netherlands
  • 1995
    • University of Amsterdam
      Amsterdamo, North Holland, Netherlands
  • 1993
    • University Hospital of Lausanne
      Lausanne, Vaud, Switzerland
  • 1991
    • Eindhoven Cancer Registry
      Eindhoven, North Brabant, Netherlands
  • 1984
    • Zeeuws Radiotherapeutisch Instituut
      Flushing, Zeeland, Netherlands
  • 1982
    • Arnhem Radiotherapy Institute
      Arnheim, Gelderland, Netherlands