Etienne Dantan

Nantes Université | UNIV Nantes

Background Time-to-event dynamic predictions are defined as the probability to survive until a defined time horizon given being event-free at landmark times and given available predictive variables at such prediction times. From two different mathematical formulations, dynamic predictions can either predict the survival probability until a final ti...

For time-to-event outcomes, the difference in restricted mean survival time is a measure of the intervention effect, an alternative to the hazard ratio, corresponding to the expected survival duration gain due to the intervention up to a predefined time t*. We extended two existing approaches of restricted mean survival time estimation for independ...

Aims For type 2 diabetes persons, we assessed the association between renal function decline and heart failure hospitalisation (HFH) and validated dynamic HFH predictions (DynHFH) based on repeated estimated Glomerular Filtration Rate (eGFR) values. Methods We studied 1413 patients from the SURDIAGENE cohort. From a joint model for longitudinal CK...

Introduction Dans les essais randomisés contrôlés présentant un critère de jugement de type survie, le risque relatif instantané (ou hazard ratio - HR) est communément utilisé pour mesurer l'effet d'un traitement. Il s'agit d'un indicateur difficile à interpréter sur le plan clinique et ce d'autant plus si l'hypothèse de proportionnalité des risque...

Bioprosthetic heart valves (BHVs) are commonly used to replace severely diseased heart valves but their susceptibility to structural valve degeneration (SVD) limits their use in young patients. We hypothesized that antibodies against immunogenic glycans present on BHVs, particularly antibodies against the xenoantigens galactose-α1,3-galactose (αGal...

Bioprosthetic heart valves (BHVs) are commonly used to replace severely diseased heart valves but their susceptibility to structural valve degeneration (SVD) limits their use in young patients. We hypothesized that antibodies against immunogenic glycans present on BHVs, particularly antibodies against the xenoantigens galactose-α1,3-galactose (αGal...

Introduction Les capacités discriminantes d’un score sont souvent rapportées en utilisant l’aire sous la courbe ROC (AUC) non-ajustée. En transplantation rénale, le Kidney Donor Risk Index (KDRI), score de qualité des greffons, a été construit sur ce modèle. Description Nous avons étudié les capacités du KDRI pour discriminer le risque d’échec de...

Objectives Patients with severe spontaneous intracranial haemorrhages, managed in intensive care units, face ethical issues regarding the difficulty of anticipating their recovery. Prognostic tools help clinicians in counselling patients and relatives and guide therapeutic decisions. We aimed to methodologically assess prognostic tools for function...

Objective We aimed to illustrate that considering covariates can lead to meaningful interpretation of the discriminative capacities of a prognostic marker. For this, we evaluated the ability of the Kidney Donor Risk Index (KDRI) to discriminate kidney graft failure risk. Study design and Setting From 4116 French patients, we estimated the adjusted...

Dans le contexte de maladies curables à longue durée d’évolution, tel qu’un cancer ou un accident vasculaire cérébral, les patients ont un risque de décès supérieur à celui de la population générale au moment du diagnostic. Leur prise en charge peut réduire le risque de décès lié à la maladie pour retrouver un risque proche de celui de la populatio...

In kidney transplantation, dynamic predictions of graft survival may be obtained from joint modelling of longitudinal and survival data for which a common assumption is that random-effects and error terms in the longitudinal sub-model are Gaussian. However, this assumption may be too restrictive, e.g. in the presence of outliers, and more flexible...

Background: In kidney transplantation, dynamic prediction of patient and kidney graft survival (DynPG) may help to promote therapeutic alliance by delivering personalized evidence-based information about long-term graft survival for kidney transplant recipients. The objective of the current study is to externally validate the DynPG. Methods: Bas...

Dynamic predictions of survival outcomes are of great interest to physicians and patients, since such predictions are useful elements of clinical decision-making. Joint modelling of longitudinal and survival data has been increasingly used to obtain dynamic predictions. A common assumption of joint modelling is that random-effects and error terms i...

Dynamic predictions of survival outcomes are of great interest to physicians and patients, since such predictions are useful elements of clinical decision-making. Joint modelling of longitudinal and survival data has been increasingly used to obtain dynamic predictions. A common assumption of joint modelling is that random-effects and error terms i...

Introduction À l’ère de la médecine 4P, les patients peuvent participer à leur prise en charge à l’aide notamment d’outils pronostiques. Le groupe TRIPOD a publié en 2015 des recommandations pour l’élaboration de ces outils pronostiques. Leur développement doit s’appuyer sur une sélection de prédicteurs combinés dans une approche multivariée à part...

Purpose From the MINDACT trial, Cardoso et al. did not demonstrate a significant efficacy for adjuvant chemotherapy (CT) for women with early-stage breast cancer presenting high clinical and low genomic risks. Our objective was to assess the usefulness of the 70-gene signature in this population by using an alternative endpoint: the number of Quali...

BACKGROUND: Informing kidney transplant recipients of their prognosis and disease progression is of primary importance in a patient-centred vision of care. By participating in decisions from the outset, transplant recipients may be more adherent to complex medical regimens due to their enhanced understanding. METHODS: We proposed to include repea...

Background: The Cancer of the Prostate Risk Assessment (CAPRA) score was designed and validated several times to predict the biochemical recurrence-free survival after a radical prostatectomy. Our objectives were, first, to study the clinical validity of the CAPRA score, and, second, to assess its clinical utility for stratified medicine from an o...

Background: The clinical utility of screening biopsies (SBs) at 1 year post-transplantation is still debated, especially for stable kidney graft recipients. Given the heterogeneity in practices between transplantation centres, the objective of this study was to compare graft and patient survival of stable patients according to whether they were fo...

Surveillance biopsies after renal transplantation remain debatable. To drive the decision of such intervention, we propose a predictive score of abnormal histology at 1‐year post‐transplantation, named 1‐Year Renal Biopsy Index (1‐RBI). We studied 466 kidney recipients from the DIVAT cohort alive with a functioning graft and a surveillance biopsy a...

Introduction En transplantation rénale, des scores pronostiques sont déjà proposés pour identifier les patients à fort risque d’échec de greffe. À partir de variables mesurées à un temps prédéfini, la prédiction du risque d’échec de greffe peut être calculée pour un temps lui aussi prédéfini. Nous avons proposé d’inclure les mesures répétées de cré...

Background: Patients with prostate cancer (PC) may be ready to make trade-offs between their quantity and their quality of life. For instance, elderly patients may prefer the absence of treatment if it is associated with a low-risk of disease progression, compared to treatments aiming at preventing disease progression but with a substantial deteri...

From a prospective and multicentric French cohort, we proposed an external validation study for the Expanded Criteria Donor (ECD), based on 4833 kidney recipients transplanted for the first time between 2000 and 2014. We estimated the subject-specific effect from a multivariable Cox model. We confirmed a 1.75-fold (95%CI from 1.53 to 2.00, p<0.0001...

Multistate models with interval-censored data, such as the illness-death model, are still not used to any considerable extent in medical research regardless of the significant literature demonstrating their advantages compared to usual survival models. Possible explanations are their uncommon availability in classical statistical software or, when...

In the context of chronic diseases, patient's health evolution is often evaluated through the study of longitudinal markers and major clinical events such as relapses or death. Dynamic predictions of such types of events may be useful to improve patients management all along their follow‐up. Dynamic predictions consist of predictions that are based...

Defining thresholds of prognostic markers is essential for stratified medicine. Such thresholds are mostly estimated from purely statistical measures regardless of patient preferences potentially leading to unacceptable medical decisions. Quality-Adjusted Life-Years are a widely used preferences-based measure of health outcomes. We develop a time-d...

In renal transplantation, serum creatinine (SCr) is the main biomarker routinely measured to assess patient’s health, with chronic increases being strongly associated with long-term graft failure risk (death with a functioning graft or return to dialysis). Joint modeling may be useful to identify the specific role of risk factors on chronic evoluti...

Introduction La mise en place d’une médecine stratifiée repose en partie sur l’utilisation de marqueurs biologiques ou cliniques ayant de bonnes aptitudes pronostiques. En transplantation rénale, le « Kidney Transplant Failure Score » (KTFS) est un score pronostiquant le retour en dialyse à huit ans post-greffe, incluant huit variables dont la créa...

Introduction: In 2002, the United Network for Organ Sharing proposed increasing the pool of donor kidneys to include Expanded Criteria Donors (ECD). Outside the U.S.A., the ECD definition remains the one used without questioning whether such a graft allocation criteria is worldwide valid. Study design: We performed a meta-analysis to quantify th...

Medical researchers are often interested to investigate the relationship between explicative variables and times-to-events such as disease progression or death. Such multiple times-to-events can be studied using multistate models. For chronic diseases, it may be relevant to consider semi-Markov multistate models because the transition intensities b...

Introduction Le cancer représente un enjeu majeur de santé publique au regard de la mortalité associée. D’ici 2020, plus de 10 millions de patients atteints d’un cancer devraient décéder chaque année. Cependant, de grands espoirs sont possibles grâce aux découvertes de biomarqueurs prédictifs des réponses aux traitements. De nombreuses méta-analyse...

Introduction Dans le suivi des maladies chroniques, un marqueur longitudinal est souvent étudié comme reflet de l’état de santé du patient. Son évolution peut être associée à la survenue d’un évènement clinique d’intérêt (rechute, décès…) sans pour autant que cette relation soit déterministe. En transplantation rénale, le taux de créatinine sanguin...

Introduction En médecine stratifiée, l’identification de marqueurs pronostiques de la survenue d’un événement d’intérêt est primordiale pour la mise en place de stratégies thérapeutiques adaptées. Mais leur utilisation est conditionnée par l’identification de valeurs seuils pour stratifier les patients en fonction de leur risque. Ces seuils sont so...

Although cold ischemia time has been widely studied in renal transplantation area, there is no consensus on its precise relationship with the transplantation outcomes. To study this, we sampled data from 3839 adult recipients of a first heart-beating deceased donor kidney transplanted between 2000 and 2011 within the French observational multicentr...

Objectives Predicting chronic disease evolution from a prognostic marker is a key field of research in clinical epidemiology. However, the prognostic capacity of a marker is not systematically evaluated using the appropriate methodology. We proposed the use of simple equations to calculate time-dependent sensitivity and specificity based on publish...

Data regarding the incidence and outcome of renal involvement in patients with inflammatory myopathies (IM) remain scarce. We assessed the incidence and causes of acute kidney injury (AKI) and chronic kidney disease (CKD) in 150 patients with dermatomyositis, polymyositis, and antisynthetase syndrome followed in 3 French referral centers. Renal inv...

The objective was to compare classical test theory and Rasch-family models derived from item response theory for the analysis of longitudinal patient-reported outcomes data with possibly informative intermittent missing items. A simulation study was performed in order to assess and compare the performance of classical test theory and Rasch model in...

Background: Steroid minimization strategies attempt to reduce morbidity in kidney transplantation. Concern still exists regarding long-term outcomes using either steroid withdrawal or steroid avoidance regimens. Methods: During a 10-year period, 572 primary kidney transplant recipients were treated with basiliximab, calcineurin inhibitors, and m...

In many chronic diseases, the patient's health status is followed up by quantitative markers. The evolution is often characterized by a 2-phase degradation process, that is, a normal phase followed by a pathological degradation phase preceding the disease diagnosis. We propose a joint multistate model with latent state for the joint modeling of rep...

Missing data and especially dropouts frequently arise in longitudinal data. Maximum likelihood estimates are consistent when data are missing at random (MAR) but, as this assumption is not checkable, pattern mixture models (PMM) have been developed to deal with informative dropout. More recently, latent class models (LCM) have been proposed as a wa...