Martijn W Heymans

Martijn W Heymans
Amsterdam University Medical Center | VUmc · Department of Epidemiology and Biostatistics

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426
Publications
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Publications

Publications (426)
Article
Full-text available
Aim Clinical prediction models need to be validated. In this study, we used simulation data to compare various internal and external validation approaches to validate models. Methods Data of 500 patients were simulated using distributions of metabolic tumor volume, standardized uptake value, the maximal distance between the largest lesion and anot...
Article
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The statistical quality of trial‐based economic evaluations is often suboptimal, while a comprehensive overview of available statistical methods is lacking. Therefore, this review summarized and critically appraised available statistical methods for trial‐based economic evaluations. A literature search was performed to identify studies on statistic...
Article
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Background While low back pain occurs in nearly everybody and is the leading cause of disability worldwide, we lack instruments to accurately predict persistence of acute low back pain. We aimed to develop and internally validate a machine learning model predicting non-recovery in acute low back pain and to compare this with current practice and ‘t...
Article
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Objective Traditional methods to deal with non-linearity in regression analysis often result in loss of information or compromised interpretability of the results. A recommended but underutilized method for modeling non-linear associations in regression models is spline functions. We explain spline functions in a non-mathematical way and illustrate...
Article
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Background For the development of prognostic models, after multiple imputation, variable selection is advised to be applied from the pooled model. The aim of this study is to evaluate by using a simulation study and practical data example the performance of four different pooling methods for variable selection in multiple imputed datasets. These me...
Article
Objective Longitudinal mediation effects can be estimated with mixed-effects models. Mixed-effects models are versatile, as they accommodate the estimation of contemporaneous, lagged, time-independent effects, and time-dependent effects. However, the inclusion of time lags and time interactions in mixed-effects models for longitudinal mediation ana...
Article
Objective Early identification of older people at risk of falling is the cornerstone of fall prevention. Many fall prediction tools exist but their external validity is lacking. External validation is a prerequisite before application in clinical practice. Models developed with electronic health record (EHR) data are especially challenging because...
Article
Background Definitive concomitant cisplatin-based chemoradiotherapy (CRT) is the current gold standard for most patients with advanced stage head and neck squamous cell carcinoma (HNSCC) of the pharynx and larynx. Since previous meta-analysis on CRT outcomes in HNSCC have been reported, advances have been made in radiotherapy techniques and clinica...
Article
Objective: This study tested and validated an existing tool for its ability to predict the risk of long-term (ie, ≥6 weeks) sickness absence (LTSA) after four days of sick-listing. Methods: A 9-item tool is completed online on the fourth day of sick-listing. The tool was tested in a sample (N=13 597) of food retail workers who reported sick betw...
Preprint
BACKGROUND: Real-world data are increasingly being used for as a complement to randomized controlled trials (RCTs) for evaluating the effectiveness and cost-effectiveness of healthcare interventions. Real-world data often are expected to have higher generalizability by including more representative patient populations and resembling daily clinical...
Article
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Radiotherapy (RT) is a cornerstone treatment strategy for brain tumours. Besides cytotoxicity, RT can cause disruption of the blood-brain barrier (BBB) resulting in an increased permeability into the surrounding brain parenchyma. Although this effect is generally acknowledged, it remains unclear how and to what extent different radiation schemes af...
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Background Depression and anxiety are common in visually impaired and blind adults, but often remain untreated in those who receive support from low vision service (LVS) organizations. This study aims to determine factors associated with discussing mental health by LVS workers. Methods A self-administered cross-sectional survey in one hundred LVS...
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Background Use of fall prevention strategies requires detection of high-risk patients. Our goal was to develop prediction models for falls and recurrent falls in community-dwelling older adults and to improve upon previous models by using a large, pooled sample and by considering a wide range of candidate predictors, including medications. Methods...
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Purpose: To determine which demographic and clinical characteristics are predictive of vision-related quality of life (VrQoL) and quality of life (QoL) in patients with macular oedema receiving intravitreal anti-vascular endothelial growth factor (VEGF) treatment. Methods: Vision-related quality of life (VrQoL) and quality of life (QoL) were mea...
Article
PURPOSE Baseline metabolic tumor volume (MTV) is a promising biomarker in diffuse large B-cell lymphoma (DLBCL). Our aims were to determine the best statistical relationship between MTV and survival and to compare MTV with the International Prognostic Index (IPI) and its individual components to derive the best prognostic model. METHODS PET scans...
Article
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Purpose Marker-by-treatment analyses are promising new methods in internal medicine, but have not yet been implemented in orthopaedics. With this analysis, specific cut-off points may be obtained, that can potentially identify whether meniscal surgery or physical therapy is the superior intervention for an individual patient. This study aimed to in...
Preprint
Background . For the development of prognostic models, after multiple imputation, variable selection is advised to be applied from the pooled model. The aim of this study is to evaluate by using a simulation study and practical data example the performance of four different pooling methods for variable selection in multiple imputed datasets. These...
Article
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Background In The Netherlands, low back pain patients can consult physicians specialized in musculoskeletal (MSK) medicine. Previous studies have reported on the characteristics of patients consulting MSK physicians, and the treatment options used. There are no studies yet reporting on the course of Low Back Pain (LBP) after treatment by musculoske...
Article
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Objective To develop an algorithm (sCOVID) to predict the risk of severe complications of COVID-19 in a community-dwelling population to optimise vaccination scenarios. Design Population-based cohort study. Setting 264 Dutch general practices contributing to the NL-COVID database. Participants 6074 people aged 0–99 diagnosed with COVID-19. Main...
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Background Mediation analysis methodology underwent many advancements throughout the years, with the most recent and important advancement being the development of causal mediation analysis based on the counterfactual framework. However, a previous review showed that for experimental studies the uptake of causal mediation analysis remains low. The...
Article
We aimed to determine the added value of baseline metabolic tumor volume (MTV) and interim PET (I-PET) to the age-adjusted international prognostic index (aaIPI) to predict 2-y progression-free survival (PFS) in diffuse large B-cell lymphoma. Secondary objectives were to investigate optimal I-PET response criteria (using Deauville score [DS] or qua...
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Background Accurate identification of older persons at risk of unplanned hospital visits can facilitate preventive interventions. Several risk scores have been developed to identify older adults at risk of unplanned hospital visits. It is unclear whether risk scores developed in one country, perform as well in another. This study validates seven ri...
Article
Background: The benefit of repeat hepatectomy in patients with early recurrence of colorectal cancer liver metastases (CRLM) is questioned, in particular in those suffering from recurrence within three to six months following initial hepatectomy. The aim of this review was therefore to assess whether disease-free interval was associated with overa...
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There is an increasing awareness that replication should become common practice in empirical studies. However, study results might fail to replicate for various reasons. The robustness of published study results can be assessed using the relatively new multiverse-analysis methodology, in which the robustness of the effect estimates against data ana...
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Background Confounding bias is a common concern in epidemiological research. Its presence is often determined by comparing exposure effects between univariable- and multivariable regression models, using an arbitrary threshold of a 10% difference to indicate confounding bias. However, many clinical researchers are not aware that the use of this cha...
Article
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Background Neck pain is one of the leading causes of disability in most countries and it is likely to increase further. Numerous prognostic models for people with neck pain have been developed, few have been validated. In a recent systematic review, external validation of three promising models was advised before they can be used in clinical practi...
Article
Objectives Development and internal validation of prognostic models for post-treatment and 1-year recovery in patients with neck pain in primary care. Design Prospective cohort study. Setting Primary care manual therapy practices. Participants Patients with non-specific neck pain of any duration (n = 1193). Intervention Usual care manual therap...
Article
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Interim 18F-fluorodeoxyglucose positron emission tomography (Interim-18F-FDG-PET, hereafter I-PET) has the potential to guide treatment of patients with diffuse large B-cell lymphoma (DLBCL) if the prognostic value is known. The aim of this study was to determine the optimal timing and response criteria for evaluating prognosis with I-PET in DLBCL....
Preprint
Full-text available
Objective: To develop an algorithm (sCOVID) to predict the risk of severe complications of COVID-19 in a community-dwelling population to optimise vaccination scenarios. Design: Population based cohort study Setting: 264 Dutch general practices contributing to the NL-COVID database Participants: 6074 people aged 0-99 diagnosed with COVID-19 Main ou...
Article
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Purpose: Although physical therapy is the recommended treatment in patients over 45 years old with a degenerative meniscal tear, 24% still opt for meniscal surgery. The aim was to identify those patients with a degenerative meniscal tear who will undergo surgery following physical therapy. Methods: The data for this study were generated in the p...
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Background Engaging in physical activity (PA) and avoiding sedentary behavior (SB) are important for healthy ageing with benefits including the mitigation of disability and mortality. Whether benefits extend to key determinants of disability and mortality, namely muscle strength and muscle power, is unclear. Aims This systematic review aimed to de...
Article
Background When resources are limited, occupational health survey participants are usually invited to consultations based on an occupational health provider’s subjective considerations. This study aimed to find health survey participants at risk of long-term (i.e., ≥ 42 consecutive days) sickness absence (LTSA) for consultations with occupational h...
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Objective: To investigate if cerebroplacental ratio (CPR) adds to the predictive value of umbilical artery pulsatility index (UA PI) alone - standard of practice - for adverse perinatal outcome in singleton pregnancies. Design and setting: Meta-analysis based on individual participant data (IPD). Population or sample: Ten centres provided 17 d...
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This study aims to develop and validate a prediction model of societal costs during a period of 6-months in older community care-recipients across multiple European countries. Participants were older community care-recipients from 5 European countries. The outcome measure was mean 6-months total societal costs of resource utilisation (healthcare an...
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Methodological shortcomings in prognostic modeling for patients with spinal disorders are highly common. This general commentary discusses methodological challenges related to the specific nature of this field. Five specific methodological challenges in prognostic modeling for patients with spinal disorders are presented with their potential soluti...
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Back pain is a leading cause of disability worldwide and is common in older adults. No clinical prediction models for poor long-term outcomes have been developed in older patients with back pain. This study aimed to develop and internally validate three clinical prediction models for non-recovery in this population. A prospective cohort study in ge...
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Objectives How to perform an intention to treat (ITT) analysis when a patient has a baseline value but no follow-up measurements is problematic. The purpose of this study was to compare different methods that deal with this problem, i.e. no imputation (standard and alternative mixed model analysis), single imputation (i.e. baseline value carried fo...
Article
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Our aim was to develop a prediction model for infants from the general population, with easily obtainable predictors, that accurately predicts risk of future developmental delay at age 4 and then assess its performance. Longitudinal cohort data were used (N = 1983), including full-term and preterm children. Development at age 4 was assessed using t...
Article
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Objectives To develop and internally validate prediction models to assess treatment success of both stand-alone and blended online vestibular rehabilitation (VR) in patients with chronic vestibular syndrome. Design Secondary analysis of a randomised controlled trial. Setting 59 general practices in The Netherlands. Participants 202 adults, aged...
Article
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An important recent development in mediation analysis is the use of causal mediation analysis. Causal mediation analysis decomposes the total exposure effect into causal direct and indirect effects in the presence of exposure-mediator interaction. However, in practice, traditional mediation analysis is still most widely used. The aim of this paper...
Article
Background: The risks of local recurrence and treatment-related morbidity need to be balanced after local excision of early rectal cancer. The aim of this meta-analysis was to determine oncological outcomes after local excision of pT1-2 rectal cancer followed by no additional treatment (NAT), completion total mesorectal excision (cTME) or adjuvant...
Data
Supplementary Material - Predictive value of quantitative 18F-FDG-PET radiomics analysis in patients with head and neck squamous cell carcinoma Supplement 1. All 8 radiomics factors, consisting of a spectrum of the extracted radiomics features. The number of each feature reflects the importance weight in that factor in which it is present. Supplem...
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Background Radiomics is aimed at image-based tumor phenotyping, enabling application within clinical-decision-support-systems to improve diagnostic accuracy and allow for personalized treatment. The purpose was to identify predictive 18-fluor-fluoro-2-deoxyglucose (18F-FDG) positron-emission tomography (PET) radiomic features to predict recurrence,...
Article
Introduction: Metabolic tumor volume (MTV) is a promising biomarker of pretreatment risk in diffuse large B-cell lymphoma (DLBCL). Different segmentation methods can be used which predict prognosis equally well but give different optimal cut-offs for risk stratification. Segmentation can be cumbersome meaning a fast, easy and robust method is neede...
Article
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Purpose: To conduct a meta-analysis to describe clinical course of pain and disability in adult patients post-lumbar discectomy (PROSPERO: CRD42015020806). Methods: Sensitive topic-based search strategy designed for individual databases was conducted. Patients (> 16 years) following first-time lumbar discectomy for sciatica/radiculopathy with no...
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Objectives The aim of this study was to assess the performance and impact of multilevel modelling (MLM) compared with ordinary least squares (OLS) regression in trial-based economic evaluations with clustered data.Methods Three thousand datasets with balanced and unbalanced clusters were simulated with correlation coefficients between costs and eff...
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Background: Protein intake recommendations advise ≥0.8 g/kg body weight (BW)/d, whereas experts propose a higher intake for older adults (1.0-1.2 g/kg BW/d). It is unknown whether optimal protein intake differs by sex or race. Objectives: We examined the shape of sex- and race-specific associations of dietary protein intake with 3- and 6-y chang...
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Objective This study determined if partial sick leave was associated with a shorter duration of sick leave due to musculoskeletal disorders (MSD) based on routinely collected health data in Dutch sick-listed employees. Furthermore, the effect of timing of partial sick leave on sick leave duration was determined. Methods This cohort study consisted...
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Background Lower protein intake in older adults is associated with loss of muscle mass and strength. The present study aimed to provide a pooled estimate of the overall prevalence of protein intake below recommended (according to different cut‐off values) among community‐dwelling older adults, both within the general older population and within spe...
Article
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Background: Societal expenditures on work-disability benefits is high in most Western countries. As a precursor of long-term work restrictions, long-term sickness absence (LTSA) is under continuous attention of policy makers. Different healthcare professionals can play a role in identification of persons at risk of LTSA but are not well trained. A...
Article
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Background Primary prevention of overweight is to be preferred above secondary prevention, which has shown moderate effectiveness. Objective To develop and internally validate a dynamic prediction model to identify young children in the general population, applicable at every age between birth and age 6, at high risk of future overweight (age 8). M...
Article
Background Migraine is a common disorder with high social and medical impact. Patients with migraine have a much higher chance of experiencing headache attacks as compared to the general population. Recent neuroimaging studies have confirmed that pathophysiology in the brain is not limited to the moment of the attack but is also present in between...
Article
During hospital stay after birth, preterm infants are susceptible to late-onset sepsis (LOS). To study the effect of family integrated care in single family rooms (SFRs) compared to standard care in open bay units (OBUs) on LOS. Peripheral or central venous catheters (PVCs/CVCs) and parenteral nutrition (PN) were investigated as potential mediators...
Article
In medical research, repeated questionnaire data is often used to measure and model latent variables across time. Through a novel imputation method, a direct comparison is made between latent growth analysis under classical test theory and item response theory, while also including effects of missing item responses. For classical test theory and it...
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Background Sedentary behaviour (SB) and physical activity (PA) can be objectively assessed with inertial sensors to describe bodily movement. Higher SB and lower PA is associated with higher chronological age and negative health outcomes. This study aimed to quantify the association between instrumented measures of SB (i-SB) and PA (i-PA) and morta...
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Background: Currently used performance measures for discrimination were not informative to determine the clinical benefit of predictor variables. The purpose was to evaluate if a former relevant predictor, kinesiophobia, remained clinically relevant to predict chronic occupational low back pain (LBP) in the light of a novel discriminative performa...
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Objective Competing events are often ignored in epidemiological studies. Conventional methods for the analysis of survival data assume independent or non-informative censoring, which is violated when subjects that experience a competing event are censored. Because many survival studies do not apply competing risk analysis, we explain and illustrate...