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Dive into the research topics where Willem P. Th. M. Mali is active.

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Featured researches published by Willem P. Th. M. Mali.


The Lancet | 2010

Vertebroplasty versus conservative treatment in acute osteoporotic vertebral compression fractures (Vertos II): an open-label randomised trial

Caroline A H Klazen; Paul N.M. Lohle; Jolanda De Vries; Frits H. Jansen; Alexander V. Tielbeek; Marion C Blonk; A. Venmans; Willem Jan van Rooij; Marinus C Schoemaker; Job R Juttmann; Tjoen H Lo; Harald J. J. Verhaar; Yolanda van der Graaf; Kaspar J. van Everdingen; Alex F Muller; Otto Elgersma; Dirk R Halkema; H. Fransen; Xavier Janssens; Erik Buskens; Willem P. Th. M. Mali

BACKGROUND Percutaneous vertebroplasty is increasingly used for treatment of pain in patients with osteoporotic vertebral compression fractures, but the efficacy, cost-effectiveness, and safety of the procedure remain uncertain. We aimed to clarify whether vertebroplasty has additional value compared with optimum pain treatment in patients with acute vertebral fractures. METHODS Patients were recruited to this open-label prospective randomised trial from the radiology departments of six hospitals in the Netherlands and Belgium. Patients were aged 50 years or older, had vertebral compression fractures on spine radiograph (minimum 15% height loss; level of fracture at Th5 or lower; bone oedema on MRI), with back pain for 6 weeks or less, and a visual analogue scale (VAS) score of 5 or more. Patients were randomly allocated to percutaneous vertebroplasty or conservative treatment by computer-generated randomisation codes with a block size of six. Masking was not possible for participants, physicians, and outcome assessors. The primary outcome was pain relief at 1 month and 1 year as measured by VAS score. Analysis was by intention to treat. This study is registered at ClinicalTrials.gov, number NCT00232466. FINDINGS Between Oct 1, 2005, and June 30, 2008, we identified 431 patients who were eligible for randomisation. 229 (53%) patients had spontaneous pain relief during assessment, and 202 patients with persistent pain were randomly allocated to treatment (101 vertebroplasty, 101 conservative treatment). Vertebroplasty resulted in greater pain relief than did conservative treatment; difference in mean VAS score between baseline and 1 month was -5·2 (95% CI -5·88 to -4·72) after vertebroplasty and -2·7 (-3·22 to -1·98) after conservative treatment, and between baseline and 1 year was -5·7 (-6·22 to -4·98) after vertebroplasty and -3·7 (-4·35 to -3·05) after conservative treatment. The difference between groups in reduction of mean VAS score from baseline was 2·6 (95% CI 1·74-3·37, p<0·0001) at 1 month and 2·0 (1·13-2·80, p<0·0001) at 1 year. No serious complications or adverse events were reported. INTERPRETATION In a subgroup of patients with acute osteoporotic vertebral compression fractures and persistent pain, percutaneous vertebroplasty is effective and safe. Pain relief after vertebroplasty is immediate, is sustained for at least a year, and is significantly greater than that achieved with conservative treatment, at an acceptable cost. FUNDING ZonMw; COOK Medical.


International Journal of Cancer | 2007

Risk-based selection from the general population in a screening trial : Selection criteria, recruitment and power for the Dutch-Belgian randomised lung cancer multi-slice CT screening trial (NELSON)

Carola A. van Iersel; Harry J. de Koning; Gerrit Draisma; Willem P. Th. M. Mali; Ernst Th. Scholten; Kristiaan Nackaerts; Mathias Prokop; J. Dik F. Habbema; M. Oudkerk; Rob J. van Klaveren

A method to obtain the optimal selection criteria, taking into account available resources and capacity and the impact on power, is presented for the Dutch‐Belgian randomised lung cancer screening trial (NELSON). NELSON investigates whether 16‐detector multi‐slice computed tomography screening will decrease lung cancer mortality compared to no screening. A questionnaire was sent to 335,441 (mainly) men, aged 50–75. Smoking exposure (years smoked, cigarettes/day, years quit) was determined, and expected lung cancer mortality was estimated for different selection scenarios for the 106,931 respondents, using lung cancer mortality data by level of smoking exposure (US Cancer Prevention Study I and II). Selection criteria were chosen so that the required response among eligible subjects to reach sufficient sample size was minimised and the required sample size was within our capacity. Inviting current and former smokers (quit ≤ 10 years ago) who smoked >15 cigarettes/day during >25 years or >10 cigarettes/day during >30 years was most optimal. With a power of 80%, 17,300–27,900 participants are needed to show a 20–25% lung cancer mortality reduction 10 years after randomisation. Until October 18, 2005 11,103 (first recruitment round) and 4,325 (second recruitment round) (total = 15,428) participants have been randomised. Selecting participants for lung cancer screening trials based on risk estimates is feasible and helpful to minimize sample size and costs. When pooling with Danish trial data (n = ±4,000) NELSON is the only trial without screening in controls that is expected to have 80% power to show a lung cancer mortality reduction of at least 25% 10 years after randomisation.


The Lancet | 2010

Short-term outcome after stenting versus endarterectomy for symptomatic carotid stenosis: a preplanned meta-analysis of individual patient data.

Leo H. Bonati; Joanna Dobson; Ale Algra; A Branchereau; Gilles Chatellier; Gustav Fraedrich; Willem P. Th. M. Mali; Hermann Zeumer; Martin M. Brown; Jean-Louis Mas; Peter A. Ringleb

BACKGROUND Results from randomised controlled trials have shown a higher short-term risk of stroke associated with carotid stenting than with carotid endarterectomy for the treatment of symptomatic carotid stenosis. However, these trials were underpowered for investigation of whether carotid artery stenting might be a safe alternative to endarterectomy in specific patient subgroups. We therefore did a preplanned meta-analysis of individual patient data from three randomised controlled trials. METHODS Data from all 3433 patients with symptomatic carotid stenosis who were randomly assigned and analysed in the Endarterectomy versus Angioplasty in Patients with Symptomatic Severe Carotid Stenosis (EVA-3S) trial, the Stent-Protected Angioplasty versus Carotid Endarterectomy (SPACE) trial, and the International Carotid Stenting Study (ICSS) were pooled and analysed with fixed-effect binomial regression models adjusted for source trial. The primary outcome event was any stroke or death. The intention-to-treat (ITT) analysis included all patients and outcome events occurring between randomisation and 120 days thereafter. The per-protocol (PP) analysis was restricted to patients receiving the allocated treatment and events occurring within 30 days after treatment. FINDINGS In the first 120 days after randomisation (ITT analysis), any stroke or death occurred significantly more often in the carotid stenting group (153 [8·9%] of 1725) than in the carotid endarterectomy group (99 [5·8%] of 1708, risk ratio [RR] 1·53, [95% CI 1·20-1·95], p=0·0006; absolute risk difference 3·2 [1·4-4·9]). Of all subgroup variables assessed, only age significantly modified the treatment effect: in patients younger than 70 years (median age), the estimated 120-day risk of stroke or death was 50 (5·8%) of 869 patients in the carotid stenting group and 48 (5·7%) of 843 in the carotid endarterectomy group (RR 1·00 [0·68-1·47]); in patients 70 years or older, the estimated risk with carotid stenting was twice that with carotid endarterectomy (103 [12·0%] of 856 vs 51 [5·9%] of 865, 2·04 [1·48-2·82], interaction p=0·0053, p=0·0014 for trend). In the PP analysis, risk estimates of stroke or death within 30 days of treatment among patients younger than 70 years were 43 (5·1%) of 851 patients in the stenting group and 37 (4·5%) of 821 in the endarterectomy group (1·11 [0·73-1·71]); in patients 70 years or older, the estimates were 87 (10·5%) of 828 patients and 36 (4·4%) of 824, respectively (2·41 [1·65-3·51]; categorical interaction p=0·0078, trend interaction p=0·0013]. INTERPRETATION Stenting for symptomatic carotid stenosis should be avoided in older patients (age ≥70 years), but might be as safe as endarterectomy in younger patients. FUNDING The Stroke Association.


The Lancet | 1998

Randomised comparison of primary stent placement versus primary angioplasty followed by selective stent placement in patients with iliac-artery occlusive disease

Eric Tetteroo; Yolanda van der Graaf; Johanna L. Bosch; Andries D. van Engelen; M. G. Myriam Hunink; B.C. Eikelboom; Willem P. Th. M. Mali

BACKGROUND Percutaneous transluminal angioplasty (PTA) is a safe, simple, and successful treatment for intermittent claudication caused by iliac-artery occlusive disease. Primary stent placement has been proposed as more effective than PTA. We compared the technical results and clinical outcomes of two treatment strategies-primary placement of a stent across the stenotic segment of the iliac artery, or primary PTA followed by selective stent placement when haemodynamic results were inadequate. METHODS We randomly assigned 279 patients with intermittent claudication, recruited from departments of vascular surgery, either to direct stent placement (group I, n=143) or primary angioplasty (group II, n=136), with subsequent stent placement in case of a residual mean pressure gradient greater than 10 mm Hg across the treated site. The main inclusion criterion was intermittent claudication on the basis of iliac-artery stenosis of more than 50%, proven by angiography. All patients had a clinical assessment before intervention and at 3, 12, and 24 months. Clinical success was defined as improvement of at least one clinical category. Secondary endpoints were initial technical results, procedural complications, cumulative patency as assessed by duplex ultrasonography, and quality of life. FINDINGS In group II, selective stent placement was done in 59 (43%) of the 136 patients. The mean follow-up was 9.3 months (range 3-24). Initial haemodynamic success and complication rates were 119 (81%) of 149 limbs and 6 (4%) of 143 limbs (group I) versus 103 (82%) of 126 limbs and 10 (7%) of 136 limbs (group II), respectively. Clinical success rates at 2 years were 29 (78%) of 37 patients and 26 (77%) of 34 patients in groups I and II, respectively (p=0.6); however, 43% and 35% of the patients, respectively, still had symptoms. Quality of life improved significantly after intervention (p<0.05) but we found no difference between the groups during follow-up. 2-year cumulative patency rates were similar at 71% versus 70% (p=0.2), respectively, as were reintervention rates at 7% versus 4%, respectively (95% CI -2% to 9%). INTERPRETATION There were no substantial differences in technical results and clinical outcomes of the two treatment strategies both at short-term and long-term follow-up. Since angioplasty followed by selective stent placement is less expensive than direct placement of a stent, the former seems to be the treatment of choice for lifestyle-limiting intermittent claudication caused by iliac artery occlusive disease.


Circulation | 1995

Paradoxical arterial wall shrinkage may contribute to luminal narrowing of human atherosclerotic femoral arteries

Gerard Pasterkamp; Peter J. W. Wensing; Mark J. Post; Berend Hillen; Willem P. Th. M. Mali; Cornelius Borst

BACKGROUND This study was done to assess how local changes in vessel size, together with plaque load, determine luminal narrowing in atherosclerotic arteries. Fifty-one human femoral arteries were analyzed: 32 postmortem and 19 in vivo by 30-MHz intravascular ultrasound. METHODS AND RESULTS Histological and intravascular ultrasound cross sections were examined every 0.5 cm over an arterial segment 10 to 15 cm long. In each cross section we measured the lumen area and the area circumscribed by the internal elastic lamina (the IEL area). In each arterial segment, the cross section that contained the least amount of plaque was the reference site. For each cross section, the lumen area stenosis was expressed as percent of the lumen area in the reference site. Similarly, the IEL area was expressed as percent of the IEL area in the reference site (the relative IEL area). There was a significant negative correlation between the relative IEL area and the lumen area stenosis percentage (r = -.62, P < .001 for histology and r = -.66, P < .001 for intravascular ultrasound). When lumen area stenosis was less than about 25%, mainly compensatory enlargement was observed. When lumen area stenosis exceeded about 25%, however, mainly a decrease of the IEL area was observed, which is consistent with arterial wall shrinkage. Furthermore, the increase in plaque area does not account for the total loss of luminal area. There was a moderate correlation between an increase in plaque area and reduction of the corresponding lumen area (r = .49 and r = .56 for histology and intravascular ultrasound, respectively). CONCLUSIONS The decrease in luminal area cannot be attributed to plaque increase alone. Arterial wall shrinkage is a paradoxical mechanism that may contribute to severe luminal narrowing of the atherosclerotic human femoral artery.


Stroke | 2002

Preoperative Diagnosis of Carotid Artery Stenosis Accuracy of Noninvasive Testing

Paul J. Nederkoorn; Willem P. Th. M. Mali; B.C. Eikelboom; Otto E. H. Elgersma; Erik Buskens; M. G. Myriam Hunink; L. Jaap Kappelle; Pieter C. Buijs; Aloys F. J. Wüst; Aad van der Lugt; Yolanda van der Graaf

Background and Purpose— Carotid endarterectomy has been shown to be beneficial in symptomatic patients with a severe stenosis (70% to 99%) of the internal carotid artery (ICA). Digital subtraction angiography (DSA) is the standard of reference in the diagnosis of carotid artery stenosis but has a relatively high complication rate. In a diagnostic study we investigated the accuracy of noninvasive testing compared with DSA. Methods— In a prospective diagnostic study we performed duplex ultrasound (DUS), magnetic resonance angiography (MRA), and DSA on 350 consecutive symptomatic patients. Stenoses were measured with the observers blinded for clinical information and other test results. Separate and combined test results of DUS and MRA were compared with the reference standard DSA. Only the stenosis measurements of the arteries on the symptomatic side were included in the analyses. Results— DUS analyzed with previously defined criteria resulted in a sensitivity of 87.5% (95% CI, 82.1% to 92.9%) and a specificity of 75.7% (95% CI, 69.3% to 82.2%) in identifying severe ICA stenosis (70% to 99%). Stenosis measurements on MRA yielded a sensitivity of 92.2% (95% CI, 86.2% to 96.2%) and a specificity of 75.7% (95% CI, 68.6% to 82.5%). When we combined MRA and DUS results, agreement between these 2 modalities (84% of patients) gave a sensitivity of 96.3% (95% CI, 90.8% to 99.0%) and a specificity of 80.2% (95% CI, 73.1% to 87.3%) for identifying severe stenosis. Conclusions— MRA showed a slightly better accuracy than DUS in the diagnosis of carotid artery stenosis. To achieve the best accuracy, however, both tests should be performed subsequently.


The Lancet | 2015

Long-term outcomes after stenting versus endarterectomy for treatment of symptomatic carotid stenosis : the International Carotid Stenting Study (ICSS) randomised trial

Leo H. Bonati; Joanna Dobson; Roland L Featherstone; Jörg Ederle; H. Bart van der Worp; Gert Jan de Borst; Willem P. Th. M. Mali; Jonathan Beard; Trevor J. Cleveland; Stefan T. Engelter; Philippe Lyrer; Gary A. Ford; Paul J Dorman; Martin M. Brown

Summary Background Stenting is an alternative to endarterectomy for treatment of carotid artery stenosis, but long-term efficacy is uncertain. We report long-term data from the randomised International Carotid Stenting Study comparison of these treatments. Methods Patients with symptomatic carotid stenosis were randomly assigned 1:1 to open treatment with stenting or endarterectomy at 50 centres worldwide. Randomisation was computer generated centrally and allocated by telephone call or fax. Major outcomes were assessed by an independent endpoint committee unaware of treatment assignment. The primary endpoint was fatal or disabling stroke in any territory after randomisation to the end of follow-up. Analysis was by intention to treat ([ITT] all patients) and per protocol from 31 days after treatment (all patients in whom assigned treatment was completed). Functional ability was rated with the modified Rankin scale. This study is registered, number ISRCTN25337470. Findings 1713 patients were assigned to stenting (n=855) or endarterectomy (n=858) and followed up for a median of 4·2 years (IQR 3·0–5·2, maximum 10·0). Three patients withdrew immediately and, therefore, the ITT population comprised 1710 patients. The number of fatal or disabling strokes (52 vs 49) and cumulative 5-year risk did not differ significantly between the stenting and endarterectomy groups (6·4% vs 6·5%; hazard ratio [HR] 1·06, 95% CI 0·72–1·57, p=0·77). Any stroke was more frequent in the stenting group than in the endarterectomy group (119 vs 72 events; ITT population, 5-year cumulative risk 15·2% vs 9·4%, HR 1·71, 95% CI 1·28–2·30, p<0·001; per-protocol population, 5-year cumulative risk 8·9% vs 5·8%, 1·53, 1·02–2·31, p=0·04), but were mainly non-disabling strokes. The distribution of modified Rankin scale scores at 1 year, 5 years, or final follow-up did not differ significantly between treatment groups. Interpretation Long-term functional outcome and risk of fatal or disabling stroke are similar for stenting and endarterectomy for symptomatic carotid stenosis. Funding Medical Research Council, Stroke Association, Sanofi-Synthélabo, European Union.


Biological Psychiatry | 1999

Volumetric analysis of frontal lobe regions in schizophrenia : relation to cognitive function and symptomatology

W.F.C. Baaré; Hilleke E. Hulshoff Pol; Ron Hijman; Willem P. Th. M. Mali; Max A. Viergever; René S. Kahn

BACKGROUND The purpose of this study was to examine the structure of dorsolateral, medial, and orbital regions of the frontal lobe in schizophrenia, and to determine whether their volumetric measurements were related to cognitive function and symptomatology. METHODS High resolution magnetic resonance imaging scans of the brains of 14 schizophrenic patients and 14 closely matched healthy controls were acquired. Volumes of gray and white matter of the left and right dorsolateral, medial, and orbital prefrontal brain regions were measured. Tests of verbal and visual memory and executive functions were used to assess cognitive function. The SANS and SAPS were used to obtain symptom ratings in patients. RESULTS Data of 13 schizophrenic patients were analyzed. Patients showed a general, though not significant, decrease in volumes of frontal regions as compared to controls. In patients, but not in controls, smaller left and right prefrontal gray matter volumes were significantly correlated with impaired performance on immediate recall in verbal and visual memory and semantic fluency. Furthermore, in patients, smaller total orbitofrontal gray matter volume was significantly correlated with more severe negative symptomatology (rs = -.76, p = .006). CONCLUSIONS These findings suggest that in schizophrenia, deficits in verbal and visual memory and semantic fluency and negative symptoms may be related to (subtle) abnormalities in frontal lobe structure.


Stroke | 1999

Circle of Willis Collateral Flow Investigated by Magnetic Resonance Angiography

Monique J. Hartkamp; Jeroen van der Grond; Kaspar J. van Everdingen; Berend Hillen; Willem P. Th. M. Mali

BACKGROUND AND PURPOSE The circle of Willis (CW) is considered an important collateral pathway in maintaining adequate cerebral blood flow in patients with internal carotid artery (ICA) obstruction. We aimed to investigate the anatomic variation of the CW in patients with severe symptomatic carotid obstructive disease and to analyze diameter changes of its components in relation to varying grades of ICA obstruction and in relation to the presence or absence of (retrograde) collateral flow. METHODS Seventy-five patients with minor disabling neurological deficits and with ICA stenoses or occlusions were categorized into 4 groups according to the severity of ICA obstruction. This patient population reflected a relatively favorable subgroup of cerebral infarction (considering their minor neurological deficits). All subjects underwent magnetic resonance angiography, including magnetic resonance angiography sensitive to flow direction. CW morphology and the size of its components were determined and compared with those values in control subjects (n=100). RESULTS Compared with control subjects, patients demonstrated a significantly higher percentage of entirely complete CW configurations (55% versus 36%, P=0.02), complete anterior configurations (88% versus 68%, P=0.002), and complete posterior CW configurations (63% versus 47%, P=0.04). Patients with severe ICA stenosis did not show significantly increased CW vessel diameters. Patients with ICA occlusion demonstrated a high prevalence of collateral flow through the anterior CW and significantly increased diameters of the communicating channels. Patients with bilateral ICA occlusion relied on collateral flow via the posterior CW and demonstrated a bilateral increase in posterior communicating artery diameters (P<0.05). CONCLUSIONS The anatomic and functional configuration of the CW reflects the degree of ICA obstruction.


Diabetes Care | 2010

Progression of cerebral atrophy and white matter hyperintensities in patients with type 2 diabetes

Jeroen de Bresser; A.M. Tiehuis; Esther van den Berg; Yael D. Reijmer; Cynthia Jongen; L. Jaap Kappelle; Willem P. Th. M. Mali; Max A. Viergever; Geert Jan Biessels

OBJECTIVE Type 2 diabetes is associated with a moderate degree of cerebral atrophy and a higher white matter hyperintensity (WMH) volume. How these brain-imaging abnormalities evolve over time is unknown. The present study aims to quantify cerebral atrophy and WMH progression over 4 years in type 2 diabetes. RESEARCH DESIGN AND METHODS A total of 55 patients with type 2 diabetes and 28 age-, sex-, and IQ-matched control participants had two 1.5T magnetic resonance imaging scans with a 4-year interval. Volumetric measurements of total brain, peripheral cerebrospinal fluid (CSF), lateral ventricles, and WMH were performed with k-nearest neighbor–based probabilistic segmentation. All volumes were expressed as percentage of intracranial volume. Linear regression analyses, adjusted for age and sex, were performed to compare brain volumes between the groups and to identify determinants of volumetric change within the type 2 diabetic group. RESULTS At baseline, patients with type 2 diabetes had a significantly smaller total brain volume and larger peripheral CSF volume than control participants. In both groups, all volumes showed a significant change over time. Patients with type 2 diabetes had a greater increase in lateral ventricular volume than control participants (mean adjusted between-group difference in change over time [95% CI]: 0.11% in 4 years [0.00 to 0.22], P = 0.047). CONCLUSIONS The greater increase in lateral ventricular volume over time in patients with type 2 diabetes compared with control participants shows that type 2 diabetes is associated with a slow increase of cerebral atrophy over the course of years.

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Matthijs Oudkerk

University Medical Center Groningen

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Harry J. de Koning

Erasmus University Rotterdam

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